CA1171837A - Silicon substituted zeolite compositions and process for preparing same - Google Patents
Silicon substituted zeolite compositions and process for preparing sameInfo
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- CA1171837A CA1171837A CA000392137A CA392137A CA1171837A CA 1171837 A CA1171837 A CA 1171837A CA 000392137 A CA000392137 A CA 000392137A CA 392137 A CA392137 A CA 392137A CA 1171837 A CA1171837 A CA 1171837A
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Abstract
ABSTRACT OF DISCLOSURE
Aluminum from AlO4 - tetrahedra of as-synthesized zeolites is extracted and substituted with silicon to form zeolite compositions having higher SiO2/A12O3 molar ratios and exhibiting distinctive chemical and physical properties.
The preparative procedure involves contact of the starting zeolite with an aqueous solution of a fluorosilicate salt using controlled proportions and temperature and pH condi-tions which avoid aluminum exeraction without silicon sub-stitution.
Aluminum from AlO4 - tetrahedra of as-synthesized zeolites is extracted and substituted with silicon to form zeolite compositions having higher SiO2/A12O3 molar ratios and exhibiting distinctive chemical and physical properties.
The preparative procedure involves contact of the starting zeolite with an aqueous solution of a fluorosilicate salt using controlled proportions and temperature and pH condi-tions which avoid aluminum exeraction without silicon sub-stitution.
Description
1~71837 The present invention relates in general to novel zeolite compositions and to the method for their prePara-tion. More particularly it relates to zeolite compositions topologically related to prior known zeolites but which have substantially greater SiO2/A1203 molar ratios than the heretofore known zeolite species and characterized by containin~, framework silicon atoms from an extraneous source, and preferably a very low content of defect sites in the struc-ture. In general the preparative process involves contactin~
the starting zeolite under controlled conditions with an aqueous solution of a fluorosilicate salt, preferablv one which toes not form insoluble salts with aluminum.
The crystal structures of naturally occurring and as-synthesized zeolitic aluminosilicates are composed of A104 and SiO4 tetrahedra which are cross-linked by the sharing of oxygen atoms. The electrovalence of each tetra-hedron containing an aluminum atom is balanced by associa~ion with a cation. Most commonly this cation is a metal cation such a~Na or K but organic species such as quaternary ammonium ions are also employed in zeolite synthesis and in some instances appear as cations in the synthesized product zeolite. In general the metal cations are, to a considerable extent at least, replaceable with other cations including H+ and NH4+, In many instances the organic cation species are too large to pass through the pore system of the zeolite and hence cannot be directly replaced by ion exchange tech-niques, Thermal treatments can reduce these organic cations to H+ or NH4+ cations which can be directly ion-exchan~ed.
Thermal treatment of the H or NH4~ cationic forms of the zeolites can result in the substantial re~oval of these cations from their normal association with the A104 tetrahedra thereby creating an electrovalent imbalance in ~, 12346-l i~7~83~7 the zeolite structure which must be accompanied by struc-tural rearrangements to restore the electrovalent balance.
Commonly when the Al04 Setrahedra constitute about 40~/~ or more of the total framework tetrahedra, the necessary structural rearrangements cannot be accommodat~d and the crystal structure colla?ses. In more siliceous zeolites, the structural integrity is substantially maintained but the resulting "decationized" form has certain significantly different properties from its fully cationized precursor.
The relative instability of aluminum in zeolites, particularly in the non-metallic cationic or the decation-ized form, is well recognized in theart. For example, in .S.P. 3,640,681, issued to P.E. Pickert on February 3, 1972, there is disclosed a process for extracting framework aluminum from zeolites which involves dehydroxylating a partially cation deficient form of the zeolite and then contacting it with acetylacetone or a metal terivative thereof to chelate and solubilize aluminum atoms. Ethylenediaminetetraacetic acid has been proposed as an extractant for aluminum from a zeolite framework in a process which is in some respects similar to the Pickert process. It is also known that calcining the H or NH4+ cation forms of zeolites such as zeolite Y in an environment of water vapor, either extraneous or derived from dehydroxylation of the zeolite itself, is effective in removing framework aluminu~ by hydrolysis.
Evidence of this phenomenon is set forth in U.S.P. 3,506,400, issued April 14, 1970 to P.E. Eberly, Jr. et al.; U.S.P.
3,493,519, issued February 3, 1970 to G.T. Rerr et al.;
and U.S.P. 3,513,108, issued May l9, 1970 to G.T. Kerr.
In those instances in which the crystal structure of the product composition is retained after the rigorous hydrothermal -1~7~837 treatment involved, infrared analysis indicated the presence of substantial hydroxyl groups exhibiting a stretching frequency in the area of about 3740, 3640 and 3550 cm 1.
The infrared analytical data of U.S.P. 3,506,400 is especially instructive in this regard. An explanation of the mechanis~
of the creation of these hydroxyl groups is provided by Xerr et al. in V.S.P. 3,493,519 wherein the patentees state that the aluminum atoms in the lattice framework of hydrogen zeolites can react with water resulting in the removal of aluminum from the lattice in accordance with the followin~
equation:
O O O
' H
-Si - 0 -Al - O -Si - 0 + 3H20 -~
O O O
O O O
' H
-Si - OH HO-Si-0 +Al(OH)3 O O O
The aluminum removet from its original lattice position is capable of further reaction with cationic hydrogen, accord-ing to Kerr et al. to yield aluminum-containing i.e. hydroxo-aluminum, cations by the equation:
O O O
' H
-Si - O -Al - O - Si - O + Al(OH) O O O' Al(OH) +
O O
-Si - O - Al - 0 Si - + H20 O O O
1~71837 It has been su~gested that stabilization ofNH4Y occurs through hydrolysis of sufficient framework aluminum to for~
stable clusters of these hydroxoaluminum cations within the sodalite ca~es, thereby holding the zeolite structure together while the framework anneals itself through the migration ofsome of the framework silicon atoms.
It is alleged in l~.S.P. 3,594,331, issued July 20, 1971 to C.H. Elliott,that fluoride ions in aqueous media, particularly under conditions in which the pH is less than about 7, are quite effective in extracting framework aluminum from zeolite lattices, and in fact when the fluoride concen-tration exceeds about 15 grams active fluoride per lO,00 grams of zeolite, destruction of the crystal lattice by the direct attack on the framework silicon as well as on the framework aluminum,can result. A fluoride treatment of thi5 type using from 2 to 22 grams of available fluoride per 10,000 grams of zeolite (anhydrous) in which the fluorine is providet by ammonium fluorosilicate is also tescribed therein. The treatment is carried out for the purpose of improving the thermal stability of the zeolite. It is theorized by the patentee tha~ the fluoride in some manner becomes attached to the constructional alkali metal oxide, thereby reducing the fluxing action of the basic structural Na20 which would otherwise result in the collapse of the crystal structure. Such treatment within the constraints of the patent disclosure has no effect on either the overall silicon content of the zeolite product or the silicon content of a unit cell of the zeolite.
Since stability quite obviously is, in part at least, a function of the SiO2/A1203 ratio of zeolites,it would appear to be advantageous to obtain zeolites having higher 1~'7~337 proportions of SiO4 tetrahedra by direct synthesis techniques and thereby avoid the structural changes inherent in frame-work aluminum extraction. Despite considerabl~ effort in this regard, however, only very modest success has been achieved, ~nd this as applied to a few individual species only. For example, over the seventeen year period since zeolite Y was first made known ~o the public as a species having an as-synthesized SiO2/A1203 molar ratio of 3 to 6, the highest SiO2/A1203 value alle~ed for an as-synthesized zeolite having the Y structure to date is 7.8 (~etherlands Patent ~o. 7306078).
We have now discovered, however, a method for removir~
framework aluminum from zeolites having SiO2/Al203 molar ratios of about 3 or greater and substituting therefor silicon from a source extraneous to the starting zeolite.
By this procedure it is possible to create more highly siliceous zeolite species which have the same crystal structure as ~ould result by direct synthesis if such synthesis method were known. In general the process comprises contacting a crystalline zeolite having pore diameters of at least about 3 Angstroms and having a molar SiO2/A1203 ratio of at least 3, with a fluorosilicate salt, preferably in an amount of at least 0.0075 moles per 100 grams of zeoli~e starting material, said fluorosillcate salt being in the form of an aqueous solution having a pH value in the range of 3 to about 7, preferably 5 to about 7, and brought into contact with the zeolite either incrementally or continuouslv at a 810w rate whereby framework aluminum atoms of the zeolite are removed and replaced by extraneous silicon atoms from the added fluorosilicate, It is desirable that the process is carried out such that at least 60, preferably at least 80, and most 1~7~837 preferably at least 90, percent of the crystal structure of the starting zeolite is retained and the Defect Structure Factor is less than 0.0~, and preferably less than 0.05 as defined hereina~ter.
The crystalline zeolite starting materials 6uitable for the practice of the present invention can be any of the well known naturally occurring or synthetically produced zeolite species which have pores large enough to permit the passage of water, fluorosilicate reagents and rea^tion products through their internal cavity system. These materials can be represented, in terms o. molar ratios of oxides, as M2/n : A123 : x Sio2 : y H20 wherein "M" is a cation having the valence "n", "x" is a value of at least about 3 and "y" has a value of from zero to about 9 depending upon the degree of hydration and the capacity of the psrticular zeolite to hold adsorbed water.
Alternatively, the framework composition can be expressed as the mole fraction of framework tetrahedra, T02, as:
~AlaSib)02 wherein "a" is the fraction of framework tetrahedral sites occupied by aluminum atoms and "b" is the fraction of framework tetrahedral sites occupied by silicon atoms.
The algebraic sum of all of the subscripts within the brackets is equal to 1. In the above example, a + b = 1.
For reasons more fully explained hereinafter, it is necessary that the starting zeolite be able to withstand the initial loss of framework aluminum atoms to at least a modest degree without collapse of the crystal structure unless the process is to be carried out at a very slow pace.
In general the ability to withstand aluminum extraction and `` 12346-1 1~7~337 maintain a high level of crystallinity is directly propor-tional to the initial SiO2/A1203 molar ratio of the zeolite.
Accordingly it is preferred that the value for "x" in the formula above be at least about 3, and more preferably at least about 3.5. Also it is preferred that at least about 50, and more preferably at least 957, of the A1~4 tetrahedra of the naturally occurring or as-synthesized zeolite are present in the starting zeolite. Most adva~-tageously the startin~ zeolite contains as many as possible of its ori~inal Al04 tetrahedra, i.e. has not been subjected to anypost-formation treatment which either extensively removes aluminum atoms from their original framework sites or converts them from the normal conditions of 4-fold coordination with oxygen.
The cation population of the starting zeolite is not a critical factor insofar as substitution of silicon for framework aluminum is concerned, but since the substitution mechanism involves the in situ formation of salts of at least some of the zeolitic cations, it is advantageous that these salts be water-soluble to a substantial degree to facilitate their removal from the silica-enriched zeolite product. It is found that ammonium cations form the most soluble salt in this regard ar.d it is accordin~ly preferred that at least 50 percent, most preferably 85 or ~ore percent, of the zeolite cations be ammonium cations.
Sodium and potassium, two of the most common original cations in zeolites are found to form Na3AlF6 and K3AlF6 respectively, both of which are only very sparingly soluble in either hot or cold water. When these compounds are formed as precipitates within the structural cavities of the zeolite they are quite difficult to remove by water washing. Tkeir removal, more-over, is important if thermal stabi'ity of the zeolite 7~ 8 37 product is desired since the substantial amounts of fluoride can cause crystal collapse at temperatures as low as 500~C.
The naturally-occurring or synthetic zeolites used as starting materials in the present process are composi-tions well-known in the art. A comprehensive review of the structure, properties and chemical compositions of crystalline zeolites is contained in Breck, D.W., "Zeolite Molecular Sieves," Wiley, New York, 1974. In those in-stances in which it i8 desirable to replace original zeolitic cations for others more preferred in the present process, conventional ion-exchange techniques are suitably employed. Especially preferred zeolite species are zeo-lite Y, zeolite rho, zeolite W, zeolite N-A, zeolite L, and the mineral and synthetic analogs of mordenite clinop-tilolite, chabazite, offretite and erionite. The fluoro-silicate salt used as the aluminum extractant and also as the source of extraneous silicon which is inserted into the zeolite structure in place of the extracted aluminum can be any of the flurosilicate salts having the general formula ~ )2/bS~6 wherein A is a metsll$c or non-metall~c cation other than H~ hav$ng the ~alence "b". Catlons re~resented by "A" are ~lkylammon~um,NH4+ , Mg~+ , L$+, Na+, K+, Ba++, Cd++, Cu+, H+, Ca~+, Cs+, Fe~+, Co~+, Pb++, Y,n+~, Rb+ , Ag~, Sr++, Tl+
~nd Zn++. The am~onium cation form o' the fluoros~licate ~s h~ghly preferred becsuse of ~ts susbstant~al solub~l~ty $n water ~nd also because the ammonium cations form water so1uble by-product sa1ts upon reaction with the zeolite, namely (NH4)3AlF6.
In certain respects, the manner in which the fluoro-silicate and starting zeo1ite are brought into contact and _ g _ ~.
~1~71B37 12346-l reacted is of critical importance. We have discovered that the overall process of substituting silicon for aluminum in the zeolite framework is a two step process in which the aluminum extraction step will, unless controlled, proceed very rapidly while the silicon insertion is relatively very slow. If dealumination becomes too extensive without sili-con substitution, the crystal structure becomes seriously degraded and ultimately collapses. While we do not wish to be bound by any particular theory, it appears that the fluo-ride ion is the agent for the extraction of framework aluminu...
in accordance with the equation.
NH4+
O O O O
(~H4)2SiF6 (soln) + A ~ S~ + (NH4)3AlF6 ~soln) o( o 6 o Zeolite Zeolite It is, therefore, essential that the initial dealumination step be inhibited and the silicon insertion step be pro~oted to achieve the desired zeolite product. It is fount that the various zeolite species have ~arying degrees of resistance toward degradation as a consequence of frame-work aluminum extraction without silicon substitution. In general the rate of aluminu~ extraction is decreased as the pH of the fluorosilicate solution in contact with the zeolite is increased within the range of 3 to 7, and as the concentration of the fluorosilicate in the reaction system is decreased. Also increasing the reaction temperature tends to increase the rate of silicon substitution. h~hether it is necessary or desirable to buffer the reaction system or strictly limit the fluorosilicate concentration is readily determined for each zeolite species by routine observation.
12346-l 1~'71837 Theoretically, there is no lower limit for the c~ncen-tration of fluorosilicate salt in the aqueous solution employed, provided of course the pH of the solution is high enough to avoid undue destructive acidic attack on the zeolite structure spart from the intended reaction with the fluoro-silicate. Very slow rates of addition of fluorosilicate salts insure that adequate time is permitted for the inser-tion of silicon as a framework substitute for extracted aluminum before excessive aluminum extraction occurs with consequent collapse of the crystal structure. Practical commercial considerations, however, require that the reaction proceed as rapidly as possible, and accordingly the conditions of reaction temperature and reagent cor,centrations should be optimized with respect to each zeolite starting material.
In general the more highly siliceous the zeolite, the higher the permissible reaction temperature and the lower the suitable pH conditions. In general the preferred reaction temperature is within the range Of 5n to 95C., but tempera-tures as high as 125C and as low as 20C have been suitably employed in some instances. At pH values below about 3 crystal degradation is generally found to be undulv severe, whereas at pH values higher than 7, silicon inser-tion is unduly low. The maximum concentration of fluoro-silicate salt in the aqueous solution employed is, of course, interdependent with the temperature and pH factors and also with the time of contact between the zeolite and the solution and the relative proportions of zeolite and fluoro-silicate. Accordingly it is possible that solutions having fluorosilicate concentrations of from about 10-3 moles per liter of solution up to saturation can be employed, but it is preferred that concentrations in the range of 0.5 to 1.0 . 12346-l 1~7~83~
moles per liter of solution be used. These concentration values are with respect to erue solutions, and are not intended to apply to the total fluorosilicate in slurries of salts in water. As illustrated hereinafter, even very slightly soluble fluorosilicates can be slurried in water and used as a reagent--the undissolved solids being readily available to replace dissolved molecular species consumed in reaction with the zeolite. As stated hereinabove, the amount of dissolved fluorosilicate employed with respect to the particular zeolite being treated will depend to some extent upon the physical and chemical properties of the individual zeolites as well as other specifications herein contained in this applicàtion. However, the minimum value for the amount of fluorosilicate to be added should be at least.equivalent to the minimum mole fraction of aluminum to be removed from the zeolite.
In this disclosure, including the appended claims, ~n specifying proportions of zeolite starting material or adsorption properties of the zeolite product, and the like, the anhydrous state of the zeolite will be intended unless otherwise stated. The anhydrous state is considered to be that obtained by heating the zeolite in dry air at 450C for 4 hours.
It is apparent from the foregoing that, with respect to reaction conditions, it is desirable that the integrity of the zeolite crystal structure is substantially maintained throughout the process, and that in addition to having extraneous (non-zeolitic) silicon atoms inserted into the lattice, the zeolite retains at least 60 and preferably at least 90 percent of its original crystallinity. A convenient technique for assessing the crystallinity of the products 117~837 relative to the crystallinity of the starting material is the comparison of the relative intensities of the d-spacings of their respective X-ray powder diffraction patterns. The sum of the peak heights, in terms of arbi-trary units above background, of the starting material is used as the standard and is compared with the corres-ponding peak heights of the products. ~Jhen, for example, the numerical sum of the peak heights of the product is 85 percent of the value of the sum of the peak heights of the starting zeolite, then 85 percent of the crystallinity has been retained. In practice it is common to utilize only a portion of the d-spacing peaks for this purpose, as for example, five of the six strongest d-spacings.
In zeolite Y these d-spacings correspond to the Miller Indices 331, 440, 533, 642 and 555. Other indicia of the crystallinity retained by the zeolite nroduct are the degree of retention of surface area and the degree of retention of the adsorption capacity. Surface areas can be determined by the well-known Brunauer-Emmett-Teller method (B-E-T).
J. Am. Chem. Soc. 60 309 (1938) using nitrogen as the atsorbate. In tetermining the atsorption capacity, the capacity for oxygen at -183C at 100 Torr is preferred.
All available evidence indicates that the present process is unique in being able to protuce zeolites essentially free of defect structure yet having molar Si02/
A12O3 ratios higher than can be obtained by direct hydro-thermal synthesis, The products resulting fro~ the operation of the process share the common characteristic of having a hi~her molar Si02/A1203 ratio than previously obtained for each species by direct hydrothermal synthesis by virtue of containing silicon from an extraneous, i.e. non-zeolitic, source, preferably in con-junction with a crystal structure which is characterized as 1~l7~837 containing a low level of tetrahedral defect sites. This defect structure, if present, is revealed by the infrared spectrum of zeolites in the hydroxyl-stretching region.
In untreated, i.e. naturally occurring or as-synthesized zeolites the original tetrahedral structure is conventionally represented as _1!, I t After treatment with a complexing agent such as ethylene-diaminetetraacetic acid (H4EDTA) in which a stoichiometric reaction occurs whereby framework aluminum atoms along with an associated cation such as sotium is removed as NaAlEDTA, it is postuiatet that the tetrahedral aluminum is replaced by four protons which form a hydroxyl "nest", AS follows:
;~o~.
_J~
The infrared spectrum of the aluminum depleted zeolite will show a broad nondescript absorption band beginning at about 3750 cm 1 and extending to about 3000 cm 1. The size of this absorption band or envelope increases with increasing aluminum depletion of the zeolite. The reason that the absorption band is so broad and without any specific absorption frequency is that the hydroxyl groups in the vacant sites in the framework are coordinated in such a way that they interact with each other (hydrogen bonding).
.. . . .
~7~837 The hydroxyl groups of adsorbed water molecules are also hydrogen-bonded and produce a similar broad absorpti~n band as do the "nest" hydroxyls. Also,certain other zeolitic hydroxyl groups, exhibiting specific characteristic absorption frequencies within the range of interest, will if present, cause infrared absorption bands in these regions which are superimposed on the band attributable to the "nest"
hydroxvl groups. These specific hydroxyls are created by the decomposition of ammonium cations or organic cations present in the zeolite.
It isl however, possible to treat zeolites, prior to subjecting them to infrared analysis, to avoid the presence of the interferrin~ hydroxyl groups and thus be able to observe the absorption attributable to the "nest" hydroxyls only. The hytroxyls belonging to atsorbet water are avoided by sub~ecting the hydrated zeolite sample to vacuum activation at a moderate temperature of about 200C. for about 1 hour. This treatment permits desorption ant removal of the atsorbed water. Complete removal of adsorbed water can be ascertained by noting when the infraret absorption bant at about 1640 cm 1, the bending frequency of water molecules, has been removed from the spectrum.
The decomposable ammonium cations can be removed, at least in large part, by ion-exchange ant replaced with metal cations, preferably by subjecting the ammonium form of the zeolite to a milt ion exchange treatment with an aqueous NaCl solution. The OH absorption bands produced by the thermal decomposition of ammonium cations are thereby avoided. Accordingly the absorption band over the range of 3745 cm 1 to about 3000 cm 1 for a zeolite so treated is almost entirely attributable to hydroxyl groups associated 1~7~837 with defect structure and the absolute absorbance of this band can be 8 measure of the degree of aluminum depletion.
It is found, however, that the ion-exchange treat~ent, which must necessarily be exhaustive even though mild, requires considerable time. Also the combination of the ion-exchange and the vacuum calcination to remove adsorbed water does not remove every possible hydroxyl other than tefect hydroxyls which can exhibit absorption in the 3745 cm 1 to 3000 cm 1 range. For instance, a rather sharp band at 3745 cm 1 has been attributed to the Si-OH groups situated in the terminal lattice positions of the zeolite crystals and to amorphous (non-zeolitic) silica from which physically adsorbed water has been removed. For these reasons we prefer to use a somewhat different criterion to measure the tegree of tefect structure in the zeolite products of this invention.
In the absence of hydrogen-bondet hytroxyl groups contributet by physically atsorbet water, the absorption frequency least affected by absorption due to hydroxyl groups other than those associatet with framework vacancies or tefect sites i9 at 3710 + 5 cm 1, Thus the relative number of tefect sites remaining in a zeolite product of this invention can be gauged by first removing any adsorbed water from the zeolite, tetermining the value of the absolute absorbance in its infraret spectrum at a frequency of 3710 cm 1, and comparing that value with the corresponding value obtainet from the spectrum of a zeolite having a known quantity of defect structure. The following specific proce-dure has been arbitrarily selected and used to measure the amount of defect structure in the products prepared in the ~71837 Examples appearing hereinafter. Using the data obtained from this procedure it is possible, using simple mathematical calculation, to obtain a single and reproducible value hereinafter referred to as the "Defect Structure Factor", denoted hereinafter by the symbol "z", which can be used in comparing and distinguishing the present novel zeolite compositions from their le~s-siliceous prior known counter-parts and also with equally siliceous prior known counter-parts prepared by other techniques.
DEFECT STRUCTURE FACTOR
.
(A) Defect Structure Zeolite Standard.
Standarts with known amounts of defect structure can be prepared by treating a crystalline zeolite of the same species as the product sample with ethylenediaminetetraacetic acit by the standart procedure of Kerr as tescribed in U.S.
Patent 3,442,795. In order to prepare the stantard it is impostant that the starting zeolite be well crystallized, substantially pure and free from tefect structure. The first two of these properties are readily tetermined by conventional X-ray analysis and the third by infrarcd analysis using the procedure set forth in part (B) hereof.
The protuct of the aluminum extraction shoult also be well crystallized ant substantially free from impurities. The amount of aluminum tepletion, i.e., the mole fraction of tetrahedral tefect structure of the standard samples can be ascertainet by conventional chemical analytical procedure.
The molar SiO2/A1203 ratio of the ~tarting zeolite used to prepare the standard sample in any ~iven case is not narrowly critical, but is preferably within about 10% of the molar SiO2/Al203 ratio of the same zeolite species used as the starting.material in the practice of the process of .
~3l7g~837 the present invention.
(B) Infrared Spectrum of Product Sample and Defect Structure Zeolite Standard.
Fifteen milligrams of the hydrated zeolite to be analyzed are pressed into a 13 mm. diameter self-supporting wafer in a KBr die under 5000 lbs. pressure. The wafer i5 then heated at 200C for l hour at a pressure of not greater than 1 x lO 4mm. Hg to remove all observable traces of physically adsorbed water from the zeolite. This condition of the zeolite is evidenced by the total absence of an infrared absorption band at 1640 cm 1. Thereafter, and without contact with adsorbable substances, particularl~:
water vapor, the infrared spectrum of the wafer is obtained on an interferometer system at 4 cm 1 resolution over the frequency range of 3745 to 3000 cm 1, Both the product sample and the stantart sample are analyzed using the same interferometer system to avoid discrepancies in the analysis due to different apparatus. The spectrum, normally obtained in the transmission mode of operation is mathematically converted to and plotted as wave number vs. absorbance.
(C) Determination of the Defect Structure Factor.
The defect structure factor (z) is calculated by substituting the appropriate tata into the following formula:
Z 3 M s) X ~Mole fraction of defects in the standard~
( P _ _ _ _ _ _ AA(std) wherein AA(ps) is the infrared absolute absorbance measured above the estimated background of the product sample at 3710 cm 1; AA(Std) is the absolute absorbance measured above the background of the standard at 3710 cm 1 and the mole fraction of defects in the standard are determined in accordance with part (A) above.
~7~837 Once the defect structure factor, z, is known, it is possible to determine from wet chemical analysis of the product sample for Si02, A1203 snd the cation content as M2/n0 whether silicon has been substituted for aluminum in the zeolite as a result of the treatment and also the efficiency of any such silicon substitution.
For purposes of simplifying these determinationS the framework compositions are best expressed in terms of mole fractions of framework tetrahedra T~ . The starting zeolite may be expressed as:
( Al cl o ) whereas "a" is tne mole fraction of aluminum tetrahedra in the framework; "b" is the mole fraction of silicon tetra-hedra in the framework; O denotes defect sites and "z" is thé
mole fraction of defect sites in the zeolite framework. In many cases the "z" value for the starting zeolite is zero and the defect sites are simply eliminated from the expression Numerically the sum of the values a ~ b + z ~ 1.
The zeolite product of the fluorosilicate treatment, expressed in terms of mole fraction of framework tetrahedra (TO2) will have the form rAl(a-N)sib+(N-~z)oz ?2 wherein: "N" is defined as the mole fraction of aluminum tetrahedra removed from the framework during the treatment "a" is the mole fraction of aluminum tetrahedra present in the framework of the starting zeolite; "b" is the mole fraction of silicon tetrahedra prescnt in the framework of the starting zeolitei "z" is the mole fraction of defect sites in the framework; (N-~z) is the mole fraction increase in silicon tetrahedra resulting from the fluoro-silicate treatment; "~z" is the net change in the mole ~L~7~8~37 fraceion of defect sites in the zeolite framework resulting from the treatment ~ Z ~ Z(product zeolite)- Z(startin~ zeolite) The term Defect Structure Factor for any given zeolite is equivalent to the "z" value of the zeolite. The net change in Defect Structure Factors between the starting zeolite and the product zeolite is equivalent to "~2". Numerically, the sum of the values:
(a-N) + ~ + (N- ~z)] + z = 1 The fact that the present process results in zeolite products having silicon substituted for aluminum in the framework is substantiated by the framework infrared spectrum in addition to the hydroxyl region infrared spectrum. In the former, there is a shift to higher wave numbers of the indicative peaks and some sharpening thereof in the case of the present products,as compared to the starting zeolite,which is due to an increaset SiO2/A1203 molar ratio.
The essential X-ray powder diffraction patterns appear-ing in this specification and referred to in the appended claims are obtained using standard X-ray powder diffraction techniques. The radiation source is a high-intensity, copper target, X-ray tube operated at 50 K~ and 40 ma.
The diffraction pattern from the copper ~ radiation and graphite monochromator is suitably recorded by an X-ray spectrometer scintillation counter, pulse-height analyzer and strip-chart recorder. Flat compressed powder samples are scanned at 2 (2 theta) per minute, using a 2 second time constant. Interplanar spacings (d) are obtained from the position of the diffraction peaks expressed as 20, where 6 is the Bragg angle as observed on the strip chart. Inten-sities are determined from the heights of diffraction peaks ~ ~ 7 1 8 3 7 12346 after substracting background.
In deter~ining the cation equivalency, ~.e. the molar ratio M2/nO/A1203, in each zeolite productl it is advantageous to perform the routine chemical analysis on a form of the zeolite in which "M" is a monovalent cation other than hydrogen. This avoids the uncertainty which can arise in the case of divalent or polyvalent metal zeolite cations as to whether the full valence of the cation is employed in balancing the net negative charge associated with each A104-tetrahedron or whether some of the positive valence of the cation is used in bonding with OH or H30~ ions.
The preferred novel crystalline aluminosilicate compositions of the present invention will contain a chemical or molar framework composition which can be determined from the expression of mole fractions of framework tetrahedra pre-viously tescribed;
[Al(a-N)Sib~(N-~z)Oz _702 wherein: the framework Si/Al ratio is teterm$ned by b + N-az and is numerically 34; the mole fraction of the a-N
aluminum tetrahedra removed from the framework of the starting zeolite, N, is ~0.3a, the mole fraction of silicon tetrahedra substituted into the framework of the product zeolite (N-^z) is increased by at least a value for N-az which is numerically ~0,5, the change in Defect Structure Factor ~z is increased by less than 0,08 ana ~referably less than 0,05.
1~711 337 Moreover, regardless of the Defect Structure Factor of any zeolite material which has been treated ac~ording to the present process, it is novel by virtue of having had extraneous silicon inserted into its crystal lattice and having 8 molar SiO2/A1203 ratio greater than heretofore obtained by direct hydrothermal synthesis. This $s necessarily the case since all other methods for increasing the SiO2/A1203 ratio of a zeolite crystal must remove framework aluminu~ -atoms, and unless at least one of those removed aluminum atoms is replacet by a silicon atom from a source other than the crystal itself, the absolute defect structure content of the crystal must be greater than the product of the present invention.
Crystal structures are more commonly described in terms of the number of tetrahedra in a unit cell. The unit cell is the basic structural unit that is repeated throughout the crystal. The number of tetrahedra in a unit cell vary widely among the various zeolite species, however. For example, the unit cell of offretite contains only 18 tetra-hedra whereas the unit cell of faujasite or a Y-type zeolite contains 192 tetrahedra. Hence the substitution of one extraneous silicon atom for one framework aluminum atom in each unit cell of offretite has a disproportionately larger effect than the same single atom substitution per unit cell of faujasite. This substantial disparity can be ameliorated to a considerable degree by regarding the framework substi-tutions as changes in the framework density of the zeolites involved, which can be expressed as the number of framework tetrahedra per lO,OOOA3. Most zeolites have a framework density of from about 130 to 190 tetrahedra per lO,OOOA3.
A more detailed description of framework density has been published by W.M. Meier, "Proceedings of the Conference on : 12346-1-C
~7~B37 Molecular Sieve (London, April 1967)," Society of Chemi-cal Intustry, (1968) pg. 19 et ~eq.
Accordingly, the novel cry6tall~ne aluminos~licstes of the present Invent~on include:
Zeolite LZ-210 having, in the dehytrated ~tate, a chemical composition expressed in terms of mole ratios of oxides as
the starting zeolite under controlled conditions with an aqueous solution of a fluorosilicate salt, preferablv one which toes not form insoluble salts with aluminum.
The crystal structures of naturally occurring and as-synthesized zeolitic aluminosilicates are composed of A104 and SiO4 tetrahedra which are cross-linked by the sharing of oxygen atoms. The electrovalence of each tetra-hedron containing an aluminum atom is balanced by associa~ion with a cation. Most commonly this cation is a metal cation such a~Na or K but organic species such as quaternary ammonium ions are also employed in zeolite synthesis and in some instances appear as cations in the synthesized product zeolite. In general the metal cations are, to a considerable extent at least, replaceable with other cations including H+ and NH4+, In many instances the organic cation species are too large to pass through the pore system of the zeolite and hence cannot be directly replaced by ion exchange tech-niques, Thermal treatments can reduce these organic cations to H+ or NH4+ cations which can be directly ion-exchan~ed.
Thermal treatment of the H or NH4~ cationic forms of the zeolites can result in the substantial re~oval of these cations from their normal association with the A104 tetrahedra thereby creating an electrovalent imbalance in ~, 12346-l i~7~83~7 the zeolite structure which must be accompanied by struc-tural rearrangements to restore the electrovalent balance.
Commonly when the Al04 Setrahedra constitute about 40~/~ or more of the total framework tetrahedra, the necessary structural rearrangements cannot be accommodat~d and the crystal structure colla?ses. In more siliceous zeolites, the structural integrity is substantially maintained but the resulting "decationized" form has certain significantly different properties from its fully cationized precursor.
The relative instability of aluminum in zeolites, particularly in the non-metallic cationic or the decation-ized form, is well recognized in theart. For example, in .S.P. 3,640,681, issued to P.E. Pickert on February 3, 1972, there is disclosed a process for extracting framework aluminum from zeolites which involves dehydroxylating a partially cation deficient form of the zeolite and then contacting it with acetylacetone or a metal terivative thereof to chelate and solubilize aluminum atoms. Ethylenediaminetetraacetic acid has been proposed as an extractant for aluminum from a zeolite framework in a process which is in some respects similar to the Pickert process. It is also known that calcining the H or NH4+ cation forms of zeolites such as zeolite Y in an environment of water vapor, either extraneous or derived from dehydroxylation of the zeolite itself, is effective in removing framework aluminu~ by hydrolysis.
Evidence of this phenomenon is set forth in U.S.P. 3,506,400, issued April 14, 1970 to P.E. Eberly, Jr. et al.; U.S.P.
3,493,519, issued February 3, 1970 to G.T. Rerr et al.;
and U.S.P. 3,513,108, issued May l9, 1970 to G.T. Kerr.
In those instances in which the crystal structure of the product composition is retained after the rigorous hydrothermal -1~7~837 treatment involved, infrared analysis indicated the presence of substantial hydroxyl groups exhibiting a stretching frequency in the area of about 3740, 3640 and 3550 cm 1.
The infrared analytical data of U.S.P. 3,506,400 is especially instructive in this regard. An explanation of the mechanis~
of the creation of these hydroxyl groups is provided by Xerr et al. in V.S.P. 3,493,519 wherein the patentees state that the aluminum atoms in the lattice framework of hydrogen zeolites can react with water resulting in the removal of aluminum from the lattice in accordance with the followin~
equation:
O O O
' H
-Si - 0 -Al - O -Si - 0 + 3H20 -~
O O O
O O O
' H
-Si - OH HO-Si-0 +Al(OH)3 O O O
The aluminum removet from its original lattice position is capable of further reaction with cationic hydrogen, accord-ing to Kerr et al. to yield aluminum-containing i.e. hydroxo-aluminum, cations by the equation:
O O O
' H
-Si - O -Al - O - Si - O + Al(OH) O O O' Al(OH) +
O O
-Si - O - Al - 0 Si - + H20 O O O
1~71837 It has been su~gested that stabilization ofNH4Y occurs through hydrolysis of sufficient framework aluminum to for~
stable clusters of these hydroxoaluminum cations within the sodalite ca~es, thereby holding the zeolite structure together while the framework anneals itself through the migration ofsome of the framework silicon atoms.
It is alleged in l~.S.P. 3,594,331, issued July 20, 1971 to C.H. Elliott,that fluoride ions in aqueous media, particularly under conditions in which the pH is less than about 7, are quite effective in extracting framework aluminum from zeolite lattices, and in fact when the fluoride concen-tration exceeds about 15 grams active fluoride per lO,00 grams of zeolite, destruction of the crystal lattice by the direct attack on the framework silicon as well as on the framework aluminum,can result. A fluoride treatment of thi5 type using from 2 to 22 grams of available fluoride per 10,000 grams of zeolite (anhydrous) in which the fluorine is providet by ammonium fluorosilicate is also tescribed therein. The treatment is carried out for the purpose of improving the thermal stability of the zeolite. It is theorized by the patentee tha~ the fluoride in some manner becomes attached to the constructional alkali metal oxide, thereby reducing the fluxing action of the basic structural Na20 which would otherwise result in the collapse of the crystal structure. Such treatment within the constraints of the patent disclosure has no effect on either the overall silicon content of the zeolite product or the silicon content of a unit cell of the zeolite.
Since stability quite obviously is, in part at least, a function of the SiO2/A1203 ratio of zeolites,it would appear to be advantageous to obtain zeolites having higher 1~'7~337 proportions of SiO4 tetrahedra by direct synthesis techniques and thereby avoid the structural changes inherent in frame-work aluminum extraction. Despite considerabl~ effort in this regard, however, only very modest success has been achieved, ~nd this as applied to a few individual species only. For example, over the seventeen year period since zeolite Y was first made known ~o the public as a species having an as-synthesized SiO2/A1203 molar ratio of 3 to 6, the highest SiO2/A1203 value alle~ed for an as-synthesized zeolite having the Y structure to date is 7.8 (~etherlands Patent ~o. 7306078).
We have now discovered, however, a method for removir~
framework aluminum from zeolites having SiO2/Al203 molar ratios of about 3 or greater and substituting therefor silicon from a source extraneous to the starting zeolite.
By this procedure it is possible to create more highly siliceous zeolite species which have the same crystal structure as ~ould result by direct synthesis if such synthesis method were known. In general the process comprises contacting a crystalline zeolite having pore diameters of at least about 3 Angstroms and having a molar SiO2/A1203 ratio of at least 3, with a fluorosilicate salt, preferably in an amount of at least 0.0075 moles per 100 grams of zeoli~e starting material, said fluorosillcate salt being in the form of an aqueous solution having a pH value in the range of 3 to about 7, preferably 5 to about 7, and brought into contact with the zeolite either incrementally or continuouslv at a 810w rate whereby framework aluminum atoms of the zeolite are removed and replaced by extraneous silicon atoms from the added fluorosilicate, It is desirable that the process is carried out such that at least 60, preferably at least 80, and most 1~7~837 preferably at least 90, percent of the crystal structure of the starting zeolite is retained and the Defect Structure Factor is less than 0.0~, and preferably less than 0.05 as defined hereina~ter.
The crystalline zeolite starting materials 6uitable for the practice of the present invention can be any of the well known naturally occurring or synthetically produced zeolite species which have pores large enough to permit the passage of water, fluorosilicate reagents and rea^tion products through their internal cavity system. These materials can be represented, in terms o. molar ratios of oxides, as M2/n : A123 : x Sio2 : y H20 wherein "M" is a cation having the valence "n", "x" is a value of at least about 3 and "y" has a value of from zero to about 9 depending upon the degree of hydration and the capacity of the psrticular zeolite to hold adsorbed water.
Alternatively, the framework composition can be expressed as the mole fraction of framework tetrahedra, T02, as:
~AlaSib)02 wherein "a" is the fraction of framework tetrahedral sites occupied by aluminum atoms and "b" is the fraction of framework tetrahedral sites occupied by silicon atoms.
The algebraic sum of all of the subscripts within the brackets is equal to 1. In the above example, a + b = 1.
For reasons more fully explained hereinafter, it is necessary that the starting zeolite be able to withstand the initial loss of framework aluminum atoms to at least a modest degree without collapse of the crystal structure unless the process is to be carried out at a very slow pace.
In general the ability to withstand aluminum extraction and `` 12346-1 1~7~337 maintain a high level of crystallinity is directly propor-tional to the initial SiO2/A1203 molar ratio of the zeolite.
Accordingly it is preferred that the value for "x" in the formula above be at least about 3, and more preferably at least about 3.5. Also it is preferred that at least about 50, and more preferably at least 957, of the A1~4 tetrahedra of the naturally occurring or as-synthesized zeolite are present in the starting zeolite. Most adva~-tageously the startin~ zeolite contains as many as possible of its ori~inal Al04 tetrahedra, i.e. has not been subjected to anypost-formation treatment which either extensively removes aluminum atoms from their original framework sites or converts them from the normal conditions of 4-fold coordination with oxygen.
The cation population of the starting zeolite is not a critical factor insofar as substitution of silicon for framework aluminum is concerned, but since the substitution mechanism involves the in situ formation of salts of at least some of the zeolitic cations, it is advantageous that these salts be water-soluble to a substantial degree to facilitate their removal from the silica-enriched zeolite product. It is found that ammonium cations form the most soluble salt in this regard ar.d it is accordin~ly preferred that at least 50 percent, most preferably 85 or ~ore percent, of the zeolite cations be ammonium cations.
Sodium and potassium, two of the most common original cations in zeolites are found to form Na3AlF6 and K3AlF6 respectively, both of which are only very sparingly soluble in either hot or cold water. When these compounds are formed as precipitates within the structural cavities of the zeolite they are quite difficult to remove by water washing. Tkeir removal, more-over, is important if thermal stabi'ity of the zeolite 7~ 8 37 product is desired since the substantial amounts of fluoride can cause crystal collapse at temperatures as low as 500~C.
The naturally-occurring or synthetic zeolites used as starting materials in the present process are composi-tions well-known in the art. A comprehensive review of the structure, properties and chemical compositions of crystalline zeolites is contained in Breck, D.W., "Zeolite Molecular Sieves," Wiley, New York, 1974. In those in-stances in which it i8 desirable to replace original zeolitic cations for others more preferred in the present process, conventional ion-exchange techniques are suitably employed. Especially preferred zeolite species are zeo-lite Y, zeolite rho, zeolite W, zeolite N-A, zeolite L, and the mineral and synthetic analogs of mordenite clinop-tilolite, chabazite, offretite and erionite. The fluoro-silicate salt used as the aluminum extractant and also as the source of extraneous silicon which is inserted into the zeolite structure in place of the extracted aluminum can be any of the flurosilicate salts having the general formula ~ )2/bS~6 wherein A is a metsll$c or non-metall~c cation other than H~ hav$ng the ~alence "b". Catlons re~resented by "A" are ~lkylammon~um,NH4+ , Mg~+ , L$+, Na+, K+, Ba++, Cd++, Cu+, H+, Ca~+, Cs+, Fe~+, Co~+, Pb++, Y,n+~, Rb+ , Ag~, Sr++, Tl+
~nd Zn++. The am~onium cation form o' the fluoros~licate ~s h~ghly preferred becsuse of ~ts susbstant~al solub~l~ty $n water ~nd also because the ammonium cations form water so1uble by-product sa1ts upon reaction with the zeolite, namely (NH4)3AlF6.
In certain respects, the manner in which the fluoro-silicate and starting zeo1ite are brought into contact and _ g _ ~.
~1~71B37 12346-l reacted is of critical importance. We have discovered that the overall process of substituting silicon for aluminum in the zeolite framework is a two step process in which the aluminum extraction step will, unless controlled, proceed very rapidly while the silicon insertion is relatively very slow. If dealumination becomes too extensive without sili-con substitution, the crystal structure becomes seriously degraded and ultimately collapses. While we do not wish to be bound by any particular theory, it appears that the fluo-ride ion is the agent for the extraction of framework aluminu...
in accordance with the equation.
NH4+
O O O O
(~H4)2SiF6 (soln) + A ~ S~ + (NH4)3AlF6 ~soln) o( o 6 o Zeolite Zeolite It is, therefore, essential that the initial dealumination step be inhibited and the silicon insertion step be pro~oted to achieve the desired zeolite product. It is fount that the various zeolite species have ~arying degrees of resistance toward degradation as a consequence of frame-work aluminum extraction without silicon substitution. In general the rate of aluminu~ extraction is decreased as the pH of the fluorosilicate solution in contact with the zeolite is increased within the range of 3 to 7, and as the concentration of the fluorosilicate in the reaction system is decreased. Also increasing the reaction temperature tends to increase the rate of silicon substitution. h~hether it is necessary or desirable to buffer the reaction system or strictly limit the fluorosilicate concentration is readily determined for each zeolite species by routine observation.
12346-l 1~'71837 Theoretically, there is no lower limit for the c~ncen-tration of fluorosilicate salt in the aqueous solution employed, provided of course the pH of the solution is high enough to avoid undue destructive acidic attack on the zeolite structure spart from the intended reaction with the fluoro-silicate. Very slow rates of addition of fluorosilicate salts insure that adequate time is permitted for the inser-tion of silicon as a framework substitute for extracted aluminum before excessive aluminum extraction occurs with consequent collapse of the crystal structure. Practical commercial considerations, however, require that the reaction proceed as rapidly as possible, and accordingly the conditions of reaction temperature and reagent cor,centrations should be optimized with respect to each zeolite starting material.
In general the more highly siliceous the zeolite, the higher the permissible reaction temperature and the lower the suitable pH conditions. In general the preferred reaction temperature is within the range Of 5n to 95C., but tempera-tures as high as 125C and as low as 20C have been suitably employed in some instances. At pH values below about 3 crystal degradation is generally found to be undulv severe, whereas at pH values higher than 7, silicon inser-tion is unduly low. The maximum concentration of fluoro-silicate salt in the aqueous solution employed is, of course, interdependent with the temperature and pH factors and also with the time of contact between the zeolite and the solution and the relative proportions of zeolite and fluoro-silicate. Accordingly it is possible that solutions having fluorosilicate concentrations of from about 10-3 moles per liter of solution up to saturation can be employed, but it is preferred that concentrations in the range of 0.5 to 1.0 . 12346-l 1~7~83~
moles per liter of solution be used. These concentration values are with respect to erue solutions, and are not intended to apply to the total fluorosilicate in slurries of salts in water. As illustrated hereinafter, even very slightly soluble fluorosilicates can be slurried in water and used as a reagent--the undissolved solids being readily available to replace dissolved molecular species consumed in reaction with the zeolite. As stated hereinabove, the amount of dissolved fluorosilicate employed with respect to the particular zeolite being treated will depend to some extent upon the physical and chemical properties of the individual zeolites as well as other specifications herein contained in this applicàtion. However, the minimum value for the amount of fluorosilicate to be added should be at least.equivalent to the minimum mole fraction of aluminum to be removed from the zeolite.
In this disclosure, including the appended claims, ~n specifying proportions of zeolite starting material or adsorption properties of the zeolite product, and the like, the anhydrous state of the zeolite will be intended unless otherwise stated. The anhydrous state is considered to be that obtained by heating the zeolite in dry air at 450C for 4 hours.
It is apparent from the foregoing that, with respect to reaction conditions, it is desirable that the integrity of the zeolite crystal structure is substantially maintained throughout the process, and that in addition to having extraneous (non-zeolitic) silicon atoms inserted into the lattice, the zeolite retains at least 60 and preferably at least 90 percent of its original crystallinity. A convenient technique for assessing the crystallinity of the products 117~837 relative to the crystallinity of the starting material is the comparison of the relative intensities of the d-spacings of their respective X-ray powder diffraction patterns. The sum of the peak heights, in terms of arbi-trary units above background, of the starting material is used as the standard and is compared with the corres-ponding peak heights of the products. ~Jhen, for example, the numerical sum of the peak heights of the product is 85 percent of the value of the sum of the peak heights of the starting zeolite, then 85 percent of the crystallinity has been retained. In practice it is common to utilize only a portion of the d-spacing peaks for this purpose, as for example, five of the six strongest d-spacings.
In zeolite Y these d-spacings correspond to the Miller Indices 331, 440, 533, 642 and 555. Other indicia of the crystallinity retained by the zeolite nroduct are the degree of retention of surface area and the degree of retention of the adsorption capacity. Surface areas can be determined by the well-known Brunauer-Emmett-Teller method (B-E-T).
J. Am. Chem. Soc. 60 309 (1938) using nitrogen as the atsorbate. In tetermining the atsorption capacity, the capacity for oxygen at -183C at 100 Torr is preferred.
All available evidence indicates that the present process is unique in being able to protuce zeolites essentially free of defect structure yet having molar Si02/
A12O3 ratios higher than can be obtained by direct hydro-thermal synthesis, The products resulting fro~ the operation of the process share the common characteristic of having a hi~her molar Si02/A1203 ratio than previously obtained for each species by direct hydrothermal synthesis by virtue of containing silicon from an extraneous, i.e. non-zeolitic, source, preferably in con-junction with a crystal structure which is characterized as 1~l7~837 containing a low level of tetrahedral defect sites. This defect structure, if present, is revealed by the infrared spectrum of zeolites in the hydroxyl-stretching region.
In untreated, i.e. naturally occurring or as-synthesized zeolites the original tetrahedral structure is conventionally represented as _1!, I t After treatment with a complexing agent such as ethylene-diaminetetraacetic acid (H4EDTA) in which a stoichiometric reaction occurs whereby framework aluminum atoms along with an associated cation such as sotium is removed as NaAlEDTA, it is postuiatet that the tetrahedral aluminum is replaced by four protons which form a hydroxyl "nest", AS follows:
;~o~.
_J~
The infrared spectrum of the aluminum depleted zeolite will show a broad nondescript absorption band beginning at about 3750 cm 1 and extending to about 3000 cm 1. The size of this absorption band or envelope increases with increasing aluminum depletion of the zeolite. The reason that the absorption band is so broad and without any specific absorption frequency is that the hydroxyl groups in the vacant sites in the framework are coordinated in such a way that they interact with each other (hydrogen bonding).
.. . . .
~7~837 The hydroxyl groups of adsorbed water molecules are also hydrogen-bonded and produce a similar broad absorpti~n band as do the "nest" hydroxyls. Also,certain other zeolitic hydroxyl groups, exhibiting specific characteristic absorption frequencies within the range of interest, will if present, cause infrared absorption bands in these regions which are superimposed on the band attributable to the "nest"
hydroxvl groups. These specific hydroxyls are created by the decomposition of ammonium cations or organic cations present in the zeolite.
It isl however, possible to treat zeolites, prior to subjecting them to infrared analysis, to avoid the presence of the interferrin~ hydroxyl groups and thus be able to observe the absorption attributable to the "nest" hydroxyls only. The hytroxyls belonging to atsorbet water are avoided by sub~ecting the hydrated zeolite sample to vacuum activation at a moderate temperature of about 200C. for about 1 hour. This treatment permits desorption ant removal of the atsorbed water. Complete removal of adsorbed water can be ascertained by noting when the infraret absorption bant at about 1640 cm 1, the bending frequency of water molecules, has been removed from the spectrum.
The decomposable ammonium cations can be removed, at least in large part, by ion-exchange ant replaced with metal cations, preferably by subjecting the ammonium form of the zeolite to a milt ion exchange treatment with an aqueous NaCl solution. The OH absorption bands produced by the thermal decomposition of ammonium cations are thereby avoided. Accordingly the absorption band over the range of 3745 cm 1 to about 3000 cm 1 for a zeolite so treated is almost entirely attributable to hydroxyl groups associated 1~7~837 with defect structure and the absolute absorbance of this band can be 8 measure of the degree of aluminum depletion.
It is found, however, that the ion-exchange treat~ent, which must necessarily be exhaustive even though mild, requires considerable time. Also the combination of the ion-exchange and the vacuum calcination to remove adsorbed water does not remove every possible hydroxyl other than tefect hydroxyls which can exhibit absorption in the 3745 cm 1 to 3000 cm 1 range. For instance, a rather sharp band at 3745 cm 1 has been attributed to the Si-OH groups situated in the terminal lattice positions of the zeolite crystals and to amorphous (non-zeolitic) silica from which physically adsorbed water has been removed. For these reasons we prefer to use a somewhat different criterion to measure the tegree of tefect structure in the zeolite products of this invention.
In the absence of hydrogen-bondet hytroxyl groups contributet by physically atsorbet water, the absorption frequency least affected by absorption due to hydroxyl groups other than those associatet with framework vacancies or tefect sites i9 at 3710 + 5 cm 1, Thus the relative number of tefect sites remaining in a zeolite product of this invention can be gauged by first removing any adsorbed water from the zeolite, tetermining the value of the absolute absorbance in its infraret spectrum at a frequency of 3710 cm 1, and comparing that value with the corresponding value obtainet from the spectrum of a zeolite having a known quantity of defect structure. The following specific proce-dure has been arbitrarily selected and used to measure the amount of defect structure in the products prepared in the ~71837 Examples appearing hereinafter. Using the data obtained from this procedure it is possible, using simple mathematical calculation, to obtain a single and reproducible value hereinafter referred to as the "Defect Structure Factor", denoted hereinafter by the symbol "z", which can be used in comparing and distinguishing the present novel zeolite compositions from their le~s-siliceous prior known counter-parts and also with equally siliceous prior known counter-parts prepared by other techniques.
DEFECT STRUCTURE FACTOR
.
(A) Defect Structure Zeolite Standard.
Standarts with known amounts of defect structure can be prepared by treating a crystalline zeolite of the same species as the product sample with ethylenediaminetetraacetic acit by the standart procedure of Kerr as tescribed in U.S.
Patent 3,442,795. In order to prepare the stantard it is impostant that the starting zeolite be well crystallized, substantially pure and free from tefect structure. The first two of these properties are readily tetermined by conventional X-ray analysis and the third by infrarcd analysis using the procedure set forth in part (B) hereof.
The protuct of the aluminum extraction shoult also be well crystallized ant substantially free from impurities. The amount of aluminum tepletion, i.e., the mole fraction of tetrahedral tefect structure of the standard samples can be ascertainet by conventional chemical analytical procedure.
The molar SiO2/A1203 ratio of the ~tarting zeolite used to prepare the standard sample in any ~iven case is not narrowly critical, but is preferably within about 10% of the molar SiO2/Al203 ratio of the same zeolite species used as the starting.material in the practice of the process of .
~3l7g~837 the present invention.
(B) Infrared Spectrum of Product Sample and Defect Structure Zeolite Standard.
Fifteen milligrams of the hydrated zeolite to be analyzed are pressed into a 13 mm. diameter self-supporting wafer in a KBr die under 5000 lbs. pressure. The wafer i5 then heated at 200C for l hour at a pressure of not greater than 1 x lO 4mm. Hg to remove all observable traces of physically adsorbed water from the zeolite. This condition of the zeolite is evidenced by the total absence of an infrared absorption band at 1640 cm 1. Thereafter, and without contact with adsorbable substances, particularl~:
water vapor, the infrared spectrum of the wafer is obtained on an interferometer system at 4 cm 1 resolution over the frequency range of 3745 to 3000 cm 1, Both the product sample and the stantart sample are analyzed using the same interferometer system to avoid discrepancies in the analysis due to different apparatus. The spectrum, normally obtained in the transmission mode of operation is mathematically converted to and plotted as wave number vs. absorbance.
(C) Determination of the Defect Structure Factor.
The defect structure factor (z) is calculated by substituting the appropriate tata into the following formula:
Z 3 M s) X ~Mole fraction of defects in the standard~
( P _ _ _ _ _ _ AA(std) wherein AA(ps) is the infrared absolute absorbance measured above the estimated background of the product sample at 3710 cm 1; AA(Std) is the absolute absorbance measured above the background of the standard at 3710 cm 1 and the mole fraction of defects in the standard are determined in accordance with part (A) above.
~7~837 Once the defect structure factor, z, is known, it is possible to determine from wet chemical analysis of the product sample for Si02, A1203 snd the cation content as M2/n0 whether silicon has been substituted for aluminum in the zeolite as a result of the treatment and also the efficiency of any such silicon substitution.
For purposes of simplifying these determinationS the framework compositions are best expressed in terms of mole fractions of framework tetrahedra T~ . The starting zeolite may be expressed as:
( Al cl o ) whereas "a" is tne mole fraction of aluminum tetrahedra in the framework; "b" is the mole fraction of silicon tetra-hedra in the framework; O denotes defect sites and "z" is thé
mole fraction of defect sites in the zeolite framework. In many cases the "z" value for the starting zeolite is zero and the defect sites are simply eliminated from the expression Numerically the sum of the values a ~ b + z ~ 1.
The zeolite product of the fluorosilicate treatment, expressed in terms of mole fraction of framework tetrahedra (TO2) will have the form rAl(a-N)sib+(N-~z)oz ?2 wherein: "N" is defined as the mole fraction of aluminum tetrahedra removed from the framework during the treatment "a" is the mole fraction of aluminum tetrahedra present in the framework of the starting zeolite; "b" is the mole fraction of silicon tetrahedra prescnt in the framework of the starting zeolitei "z" is the mole fraction of defect sites in the framework; (N-~z) is the mole fraction increase in silicon tetrahedra resulting from the fluoro-silicate treatment; "~z" is the net change in the mole ~L~7~8~37 fraceion of defect sites in the zeolite framework resulting from the treatment ~ Z ~ Z(product zeolite)- Z(startin~ zeolite) The term Defect Structure Factor for any given zeolite is equivalent to the "z" value of the zeolite. The net change in Defect Structure Factors between the starting zeolite and the product zeolite is equivalent to "~2". Numerically, the sum of the values:
(a-N) + ~ + (N- ~z)] + z = 1 The fact that the present process results in zeolite products having silicon substituted for aluminum in the framework is substantiated by the framework infrared spectrum in addition to the hydroxyl region infrared spectrum. In the former, there is a shift to higher wave numbers of the indicative peaks and some sharpening thereof in the case of the present products,as compared to the starting zeolite,which is due to an increaset SiO2/A1203 molar ratio.
The essential X-ray powder diffraction patterns appear-ing in this specification and referred to in the appended claims are obtained using standard X-ray powder diffraction techniques. The radiation source is a high-intensity, copper target, X-ray tube operated at 50 K~ and 40 ma.
The diffraction pattern from the copper ~ radiation and graphite monochromator is suitably recorded by an X-ray spectrometer scintillation counter, pulse-height analyzer and strip-chart recorder. Flat compressed powder samples are scanned at 2 (2 theta) per minute, using a 2 second time constant. Interplanar spacings (d) are obtained from the position of the diffraction peaks expressed as 20, where 6 is the Bragg angle as observed on the strip chart. Inten-sities are determined from the heights of diffraction peaks ~ ~ 7 1 8 3 7 12346 after substracting background.
In deter~ining the cation equivalency, ~.e. the molar ratio M2/nO/A1203, in each zeolite productl it is advantageous to perform the routine chemical analysis on a form of the zeolite in which "M" is a monovalent cation other than hydrogen. This avoids the uncertainty which can arise in the case of divalent or polyvalent metal zeolite cations as to whether the full valence of the cation is employed in balancing the net negative charge associated with each A104-tetrahedron or whether some of the positive valence of the cation is used in bonding with OH or H30~ ions.
The preferred novel crystalline aluminosilicate compositions of the present invention will contain a chemical or molar framework composition which can be determined from the expression of mole fractions of framework tetrahedra pre-viously tescribed;
[Al(a-N)Sib~(N-~z)Oz _702 wherein: the framework Si/Al ratio is teterm$ned by b + N-az and is numerically 34; the mole fraction of the a-N
aluminum tetrahedra removed from the framework of the starting zeolite, N, is ~0.3a, the mole fraction of silicon tetrahedra substituted into the framework of the product zeolite (N-^z) is increased by at least a value for N-az which is numerically ~0,5, the change in Defect Structure Factor ~z is increased by less than 0,08 ana ~referably less than 0,05.
1~711 337 Moreover, regardless of the Defect Structure Factor of any zeolite material which has been treated ac~ording to the present process, it is novel by virtue of having had extraneous silicon inserted into its crystal lattice and having 8 molar SiO2/A1203 ratio greater than heretofore obtained by direct hydrothermal synthesis. This $s necessarily the case since all other methods for increasing the SiO2/A1203 ratio of a zeolite crystal must remove framework aluminu~ -atoms, and unless at least one of those removed aluminum atoms is replacet by a silicon atom from a source other than the crystal itself, the absolute defect structure content of the crystal must be greater than the product of the present invention.
Crystal structures are more commonly described in terms of the number of tetrahedra in a unit cell. The unit cell is the basic structural unit that is repeated throughout the crystal. The number of tetrahedra in a unit cell vary widely among the various zeolite species, however. For example, the unit cell of offretite contains only 18 tetra-hedra whereas the unit cell of faujasite or a Y-type zeolite contains 192 tetrahedra. Hence the substitution of one extraneous silicon atom for one framework aluminum atom in each unit cell of offretite has a disproportionately larger effect than the same single atom substitution per unit cell of faujasite. This substantial disparity can be ameliorated to a considerable degree by regarding the framework substi-tutions as changes in the framework density of the zeolites involved, which can be expressed as the number of framework tetrahedra per lO,OOOA3. Most zeolites have a framework density of from about 130 to 190 tetrahedra per lO,OOOA3.
A more detailed description of framework density has been published by W.M. Meier, "Proceedings of the Conference on : 12346-1-C
~7~B37 Molecular Sieve (London, April 1967)," Society of Chemi-cal Intustry, (1968) pg. 19 et ~eq.
Accordingly, the novel cry6tall~ne aluminos~licstes of the present Invent~on include:
Zeolite LZ-210 having, in the dehytrated ~tate, a chemical composition expressed in terms of mole ratios of oxides as
2/n 2 3 x S~02 wherein "M" is a cation having the valence "n" ~nd "x"
is a value greater than 8, preferably greater than 9 ~re preferably and w~thin the range of 9 to 60, having an X-ray powder diffraction pattern having at least the d-spacings set forth in ~able A, below, and havin~ extraneous ~ilicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably $n an avera~e amount of at least 1.0 per lO,OOOA3.
A more lim~ted subcla6s of LZ-210 compositions, i.e.
those whlch are charactesized by having both high molar SiO2/A1203 ratios and low Defect Structure Factors, csn be tefined as having a chemical composition expresset in terms of mole fractions of framework tetrahedra as:
~ Al(a-N)Sib~ ~-~z ~z -7 2 wherein: the mole fraction of aluminum -N- removed from the framework of the starting zeolite i8 at least 0.03a; b+N- z has a value 4 and preferably greater than 4.5; the change in defect structure factor z iB less than 0.08 and pre-ferably less than 0.05; an increased silicon content in the framework, = , of at least O.S; and a cation equivalent expressed 1~71~337 as a monovalent cation species, M+/Al, from 0.8S to 1.1 and the characteristic crystal structure of zeolite Y as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth broadly in Table A, and more narrowly in Table B, below.
TABLE A TABLE B
d(A~ Intensity d(A) Intensitv 14.17-13.97 very strong 14.17-14.09 very strong 8.68- 8.55 medium 8.68- 8.62 medium 7.40- 7.30 medium 7.40- 7.35 medium 5.63- 5.55 medium 5.63- 5.5~ medium 4.72- 4.66 medium 4.72- 4.69 medium 4.34- 4.28 medium 4.34- 4.31 medium
is a value greater than 8, preferably greater than 9 ~re preferably and w~thin the range of 9 to 60, having an X-ray powder diffraction pattern having at least the d-spacings set forth in ~able A, below, and havin~ extraneous ~ilicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably $n an avera~e amount of at least 1.0 per lO,OOOA3.
A more lim~ted subcla6s of LZ-210 compositions, i.e.
those whlch are charactesized by having both high molar SiO2/A1203 ratios and low Defect Structure Factors, csn be tefined as having a chemical composition expresset in terms of mole fractions of framework tetrahedra as:
~ Al(a-N)Sib~ ~-~z ~z -7 2 wherein: the mole fraction of aluminum -N- removed from the framework of the starting zeolite i8 at least 0.03a; b+N- z has a value 4 and preferably greater than 4.5; the change in defect structure factor z iB less than 0.08 and pre-ferably less than 0.05; an increased silicon content in the framework, = , of at least O.S; and a cation equivalent expressed 1~71~337 as a monovalent cation species, M+/Al, from 0.8S to 1.1 and the characteristic crystal structure of zeolite Y as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth broadly in Table A, and more narrowly in Table B, below.
TABLE A TABLE B
d(A~ Intensity d(A) Intensitv 14.17-13.97 very strong 14.17-14.09 very strong 8.68- 8.55 medium 8.68- 8.62 medium 7.40- 7.30 medium 7.40- 7.35 medium 5.63- 5.55 medium 5.63- 5.5~ medium 4.72- 4.66 medium 4.72- 4.69 medium 4.34- 4.28 medium 4.34- 4.31 medium
3.74- 3.69 strong 3.74- 3.72 strong 3.28- 3.23 strong 3.28- 3.26 strong 2.83- 2.79 strong 2.83- 2.81~ strong The LZ-210 zeolite as defined above will have a cubic unit cell dimension, aO, o~ less than 24.55 Angstroms, preferably from 24.20 to 24.55 Angstroms and, when the molar SiO2/A1203 ratio is less than 20, an adsorption capacity for water vapor at 25C and 4.6 Torr water vapor pressure of at least 20 weight percent based on the anhydrous weight of the zeolite, and preferably an oxygen adsorption capacity o 100 Torr and -183C of at least 235 weight percent.
1~7~837 12346-1 LZ-210 can be prepared from a conventionally prepared zeolite Y which has a molar SiO2tA1203 ratio of less than 8 by using the present process to increase the SiO2/A1203 ratio greater than 8. A preferred procedure is the process embodiment which comprises.
(a) providing a zeolite Y composition havin~ a molar SiO2/A1203 ratio of not greater than 7, preferably between 3 to 6;
(b) contacting and reacting at a temperature of from 20 to 95C, said zeolite Y with a fluorosilicate, preferably ammonium fluorosilicate, in an amount of at least as great as the value "N", defined supra, wherein "N" is equal to or greater than 0.3a.
It can also be stated that:
AFS - 1.395a - 0,275 wherein AFS is the minimum number of moles of ammonium fluorosi-licate per 100 gm (anhydrous weight) of zeolite starting material ant "a" is the mole fraction of framework aluminum atoms in the zeolite starting material as statet in ~AlaSib~z)02~ sait fluorosilicate being in the form of an aqueous solution at a pH in the range of 5 to about 7, the fluorosilicate solution being brought into contact with the zeolite either incrementally or continuously at a slow rate such that a sufficient proportion of the framework 1~7~37 aluminum atoms removed are replaced by silicon atoms to retain at least 80 percent, preferably at least 90 percent, of the crystal structure of the starting zeolite Y; and (c) isolating the zeolite having an enhanced frame-work silicon content from the reaction mixture.
The starting zeolite Y composition can be synthesized by any of the processes well known in the art. Representa-tive processes are disclosed in ~.S.P. 3,130,007.
Another novel zeolite composition of the present invention is LZ-211 which has, in the dehydrated state and prior to calcination at a temperature in excess of 200C., a chemical composition expressed in terms of mole ratios of oxides as (o 9 ~ 0.1) M2~nO : A1203 : x Si2 wherein "M" is an inorganic cation having the valence "n", preferably H , NH4 or a metallic cation, and x is a value greater than 15, preferably within the range of 17 to 120, and most preferably from 17 to 35, having the characteristic crystal structure of mordenite as indicated by an X ray powder diffraction pattern having at least the d-spacings set forth in Table C, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an average amount of at least 1.0 per 10, ocoA
_ 26 -1~7~37 TABLE C
d(A) Intensity 13.5 + 0.2 Medium 9.0 + 0.2 Strong 6.5 + 0.1 Strong
1~7~837 12346-1 LZ-210 can be prepared from a conventionally prepared zeolite Y which has a molar SiO2tA1203 ratio of less than 8 by using the present process to increase the SiO2/A1203 ratio greater than 8. A preferred procedure is the process embodiment which comprises.
(a) providing a zeolite Y composition havin~ a molar SiO2/A1203 ratio of not greater than 7, preferably between 3 to 6;
(b) contacting and reacting at a temperature of from 20 to 95C, said zeolite Y with a fluorosilicate, preferably ammonium fluorosilicate, in an amount of at least as great as the value "N", defined supra, wherein "N" is equal to or greater than 0.3a.
It can also be stated that:
AFS - 1.395a - 0,275 wherein AFS is the minimum number of moles of ammonium fluorosi-licate per 100 gm (anhydrous weight) of zeolite starting material ant "a" is the mole fraction of framework aluminum atoms in the zeolite starting material as statet in ~AlaSib~z)02~ sait fluorosilicate being in the form of an aqueous solution at a pH in the range of 5 to about 7, the fluorosilicate solution being brought into contact with the zeolite either incrementally or continuously at a slow rate such that a sufficient proportion of the framework 1~7~37 aluminum atoms removed are replaced by silicon atoms to retain at least 80 percent, preferably at least 90 percent, of the crystal structure of the starting zeolite Y; and (c) isolating the zeolite having an enhanced frame-work silicon content from the reaction mixture.
The starting zeolite Y composition can be synthesized by any of the processes well known in the art. Representa-tive processes are disclosed in ~.S.P. 3,130,007.
Another novel zeolite composition of the present invention is LZ-211 which has, in the dehydrated state and prior to calcination at a temperature in excess of 200C., a chemical composition expressed in terms of mole ratios of oxides as (o 9 ~ 0.1) M2~nO : A1203 : x Si2 wherein "M" is an inorganic cation having the valence "n", preferably H , NH4 or a metallic cation, and x is a value greater than 15, preferably within the range of 17 to 120, and most preferably from 17 to 35, having the characteristic crystal structure of mordenite as indicated by an X ray powder diffraction pattern having at least the d-spacings set forth in Table C, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an average amount of at least 1.0 per 10, ocoA
_ 26 -1~7~37 TABLE C
d(A) Intensity 13.5 + 0.2 Medium 9.0 + 0.2 Strong 6.5 + 0.1 Strong
4.5 + 0.1 Medium 4.0 + 0.1 Medium 3.8 ~ 0.1 Medium 3.5 + 0.1 Strong 3 4 + 0.1 Strong 3.2 + 0.1 Strong A more limited subclass of LZ-211 compositions, i.e.
those which are characterized by having both high molar SiO2/A1203 ratios and low Defect Structure Factors, can be defined as havin~ a chemical composition expressed in terms of mole fractions of framework tetrahedra as:
[Al(a-N)Sib+(N-~z ~z ]2 wherein: the mole fraction ofaluminum, N, removed from the framework of the starting zeolite is at least 0.3a;
the Si/Al ratio has a vlaue 7.5, preferably within the range 8.5 to 30; an increase in the Defect Structure Factor "~z" of less than 0.08, an increase of silicon in the frame-work, N-~z, of st least 0.5i a cation equivalent expressed as a monovalent cation species M /Al of 0.9 1 0.1.
The precursor of LZ-211, i.e. the starting mordenite zeolite, can be any naturally-occurring or synthetic form of mordenite having a molar SiO2/A1203 ratio of not greater than 12, and in the case of the synthetic forms, svnthesized in the substantial absence of organic cations. It is 12346-l l~t7~837 immaterial whether the starting mordenit~ is of so-called small pore or large pore varieties.
The novel zeolites denominated L~-214 are the more siliceous forms of the prior known zeolite Rho and are prepared therefrom using the present process for ~ilicon substitution. LZ-214 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0-9 + 0-1 M2/n A123 x SiO2 wherein "M" is a cation having the valence "n" and "x"
is a value greater than 7, preferably in the range of 8 to 60, the characteristic crystal structure of zeolite Rho as inticatet by an X-ray powter diffraction pattern having at least the d-spacings set forth in Table D, belo~
and having extraneous silicon atoms in its crystal lattice ln the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
TABLE D
t(A) Relative Intensitv 10.5 + 0.3 . Very Strong 6.1 + 0.2 Metium Strong 4.7 + 0.2 Medium 3.52 + 0.1 Metium 3.35 + 0.1 Medium 2.94 + 0.1 Medium 2.65 + 0.1 Medium , 1~7~3~ 12346-1-C
A more limited subclass of LZ-214 compositions, i.e.
those which are characterized by having both high molar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition e~pressed in terms of mole fraction of framework tetrahedra as:
[A1(a N) Slb+(N-~z)O z]2 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite Rho is at least 0.3a; the Si/Al has a value ~4 preferably within the range 4.5 to 30; an increase in the Defect Structure Factor n az" of less than 0.08, an increase of silicon in the framework, N- ~z, of at least 0.5: a cation equivalent expressed as a N
monovalent cation species ~+/Al of 0.9 + 0.1. Zeolite Rho and the method for its manufacture are set forth in U.S.P.
3,904,738 issued September 9, 1975, and which is incorporated herein by reference.
The noval zeolites denominated L2-212 are the more siliceous forms of the prior known zeolite L and are pre-pared therefrom using the present process for silicon sub-stitution. LZ-212 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein "M" is a cation having the valence "n" and "x" is a value greater than 8, pre~eraDly in the range of 9 to 60, 1~7~37 12346-1 the characteristic crystal structure of zeolite L as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
TABLE E
d(A) Relative Intensity 15.8 + 0.2 Strong 6.0 + 0.1 Medium
those which are characterized by having both high molar SiO2/A1203 ratios and low Defect Structure Factors, can be defined as havin~ a chemical composition expressed in terms of mole fractions of framework tetrahedra as:
[Al(a-N)Sib+(N-~z ~z ]2 wherein: the mole fraction ofaluminum, N, removed from the framework of the starting zeolite is at least 0.3a;
the Si/Al ratio has a vlaue 7.5, preferably within the range 8.5 to 30; an increase in the Defect Structure Factor "~z" of less than 0.08, an increase of silicon in the frame-work, N-~z, of st least 0.5i a cation equivalent expressed as a monovalent cation species M /Al of 0.9 1 0.1.
The precursor of LZ-211, i.e. the starting mordenite zeolite, can be any naturally-occurring or synthetic form of mordenite having a molar SiO2/A1203 ratio of not greater than 12, and in the case of the synthetic forms, svnthesized in the substantial absence of organic cations. It is 12346-l l~t7~837 immaterial whether the starting mordenit~ is of so-called small pore or large pore varieties.
The novel zeolites denominated L~-214 are the more siliceous forms of the prior known zeolite Rho and are prepared therefrom using the present process for ~ilicon substitution. LZ-214 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0-9 + 0-1 M2/n A123 x SiO2 wherein "M" is a cation having the valence "n" and "x"
is a value greater than 7, preferably in the range of 8 to 60, the characteristic crystal structure of zeolite Rho as inticatet by an X-ray powter diffraction pattern having at least the d-spacings set forth in Table D, belo~
and having extraneous silicon atoms in its crystal lattice ln the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
TABLE D
t(A) Relative Intensitv 10.5 + 0.3 . Very Strong 6.1 + 0.2 Metium Strong 4.7 + 0.2 Medium 3.52 + 0.1 Metium 3.35 + 0.1 Medium 2.94 + 0.1 Medium 2.65 + 0.1 Medium , 1~7~3~ 12346-1-C
A more limited subclass of LZ-214 compositions, i.e.
those which are characterized by having both high molar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition e~pressed in terms of mole fraction of framework tetrahedra as:
[A1(a N) Slb+(N-~z)O z]2 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite Rho is at least 0.3a; the Si/Al has a value ~4 preferably within the range 4.5 to 30; an increase in the Defect Structure Factor n az" of less than 0.08, an increase of silicon in the framework, N- ~z, of at least 0.5: a cation equivalent expressed as a N
monovalent cation species ~+/Al of 0.9 + 0.1. Zeolite Rho and the method for its manufacture are set forth in U.S.P.
3,904,738 issued September 9, 1975, and which is incorporated herein by reference.
The noval zeolites denominated L2-212 are the more siliceous forms of the prior known zeolite L and are pre-pared therefrom using the present process for silicon sub-stitution. LZ-212 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein "M" is a cation having the valence "n" and "x" is a value greater than 8, pre~eraDly in the range of 9 to 60, 1~7~37 12346-1 the characteristic crystal structure of zeolite L as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
TABLE E
d(A) Relative Intensity 15.8 + 0.2 Strong 6.0 + 0.1 Medium
5.8 + 0.1 Medium weak 4.6 + 0.1 Medium 4.4 + 0.1 Medium 4.3 + 0.1 .Medium 3.9 + 0,1 Medium 3.66 + 0.1 Medium 3.48 + 0,1 Medium 3.28 + 0.1 Medium 3,18 + 0,1 Medium 3,07 + 0.1 Medium 2.91 + 0.1 Medium A more limited subclass of LZ-212 compositions, i.e, those which are characterized by having both high molar 5102/A1203 ratios and low Defect Structure Factors, can be defined as having a chemical composition can be expressed in terms of mole fraction of framework tetrahedra as:
1~7~37 12346-1-C
[Al(a-N)Slb+(N-~z)G z]2 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite L is at least 0.3a; the Si/Al has a value 34; and increase in the Defect Structure Factor, ~ z, of less than ~.08, an increase of silicon in the framework, N~__ , of at least 0.5; a cation equivalent expressed as a monovalent cation species M+/Al of 0.9 + 0.1. Zeolite L and the method for its manufacture are set forth in U.S.P. 3,216,789 issued November 9, 1965.
The novel zeolites denominated LZ-215 are the more siliceous forms of the prior known zeolite N-A and are prepared therefrom using the present process for silicon substitution. LZ-215 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein "~-- is a cation having the valence "n" and "x" is a value greater than 8, preferably in the range of 10 to 30, the characteristic crystal structure of zeolite N-A as indicated by an X-ray powder diffraction pattern having at least the d-spacin~ set forth in Table F, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per 10,000 A3.
117~837 ~ABLE F
d(A) _ Relative IntensitY
.
12.0 ~ 0.5 Very ~trong B.5 ~ 0.5 Very strong
1~7~37 12346-1-C
[Al(a-N)Slb+(N-~z)G z]2 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite L is at least 0.3a; the Si/Al has a value 34; and increase in the Defect Structure Factor, ~ z, of less than ~.08, an increase of silicon in the framework, N~__ , of at least 0.5; a cation equivalent expressed as a monovalent cation species M+/Al of 0.9 + 0.1. Zeolite L and the method for its manufacture are set forth in U.S.P. 3,216,789 issued November 9, 1965.
The novel zeolites denominated LZ-215 are the more siliceous forms of the prior known zeolite N-A and are prepared therefrom using the present process for silicon substitution. LZ-215 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein "~-- is a cation having the valence "n" and "x" is a value greater than 8, preferably in the range of 10 to 30, the characteristic crystal structure of zeolite N-A as indicated by an X-ray powder diffraction pattern having at least the d-spacin~ set forth in Table F, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per 10,000 A3.
117~837 ~ABLE F
d(A) _ Relative IntensitY
.
12.0 ~ 0.5 Very ~trong B.5 ~ 0.5 Very strong
6.9 ~ 0.2 Stron~
5-4 ~ -~ Medium 4.2 ~ 0.1 Medium 4.0 ~ 0.1 Strong 3.62 ~ 0.1 Very strong 3.33 ~ 0.1 Medium 3.20 ~ 0.1 Medium -2.91 ~ 0.1 Medium A ~ore limitèd subclass of LZ-215 co~positions, i.e.
those which are characterized by having both high molar SiO2/A1203 ratios and low Defect Structure ~actors, can be defined as having a che~ical compo6ition can ~e expressed ~n terms of mole fractions of framework tetrahedra as:
~ Al(a.N)S~+~N-~z ~z 702 wherein: the mole fraction of aluminum N, removed from the framework of the starting zeolite N-A is st least 0.3a;
the Si/Al has a ~alue~4, preferably within the range 5 to 30; an increase in the Defect Structure Factor~Dz" of less than ~,08, n increase of 6~1icon in the framework __ff_, of at lesst 0.5; 8 cation equivalent e:;pressed as a monovalent cation 6pecies M /Al of O . 9 ~ O . 1 . Zeolite ~-A
and the method for its manufacture are 6et forth in U.S.P, 3,306,922 issued February 23, 1967, 1~7~837 12346-1 The novel zeolites denominated LZ-216 are the more siliceous forms of the prior known zeolite W and are prepared therefrom using the present process for silicon substitution. LZ-216 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides O g + 0.1 M2~nO : A1203 : x SiO2 wherein "M" is a cation having the valence "n" and "x"
is a ~alue greater than 8, preferably in the sange of to 60, the characteristic crystal structure of zeolite W as indicated by an X-ray powder tiffraction pattern havin~
at least the d-spacings set forth in Table G, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferahl~ in an amount of at least 1.0 per lO,OOOA3.
TABLE G
t(A) _ Relative Intensitv 8.2 + 0.2 Medium Strong
5-4 ~ -~ Medium 4.2 ~ 0.1 Medium 4.0 ~ 0.1 Strong 3.62 ~ 0.1 Very strong 3.33 ~ 0.1 Medium 3.20 ~ 0.1 Medium -2.91 ~ 0.1 Medium A ~ore limitèd subclass of LZ-215 co~positions, i.e.
those which are characterized by having both high molar SiO2/A1203 ratios and low Defect Structure ~actors, can be defined as having a che~ical compo6ition can ~e expressed ~n terms of mole fractions of framework tetrahedra as:
~ Al(a.N)S~+~N-~z ~z 702 wherein: the mole fraction of aluminum N, removed from the framework of the starting zeolite N-A is st least 0.3a;
the Si/Al has a ~alue~4, preferably within the range 5 to 30; an increase in the Defect Structure Factor~Dz" of less than ~,08, n increase of 6~1icon in the framework __ff_, of at lesst 0.5; 8 cation equivalent e:;pressed as a monovalent cation 6pecies M /Al of O . 9 ~ O . 1 . Zeolite ~-A
and the method for its manufacture are 6et forth in U.S.P, 3,306,922 issued February 23, 1967, 1~7~837 12346-1 The novel zeolites denominated LZ-216 are the more siliceous forms of the prior known zeolite W and are prepared therefrom using the present process for silicon substitution. LZ-216 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides O g + 0.1 M2~nO : A1203 : x SiO2 wherein "M" is a cation having the valence "n" and "x"
is a ~alue greater than 8, preferably in the sange of to 60, the characteristic crystal structure of zeolite W as indicated by an X-ray powder tiffraction pattern havin~
at least the d-spacings set forth in Table G, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferahl~ in an amount of at least 1.0 per lO,OOOA3.
TABLE G
t(A) _ Relative Intensitv 8.2 + 0.2 Medium Strong
7.1 + 0.2 Very Strong 5.3 + 0.1 Metium Strong S.0 + 0.1 Medium Strong 4.5 + 0.1 Medium 4.31 + 0.1 Metium 3.67 + 0.1 Medium 1~7~837 TABLE G (continued) d(A) _ Relative Intensity 3.25 t 0.1 Strong 3.17 ~ 0.1 Strong 2.96 ~ 0.1 Medium 2.73 ~ 0.1 Medium 2.55 ~ 0.1 Medium A more limited ~ubclass of LZ-216 compositions, i.e., those which are characterized by having both high molar SiO2/A1203 ratios and low Defect Structure Factors, can be defined as having a chemical composition expressed $n terms of mole fractions of framework tetrahedra as:
[Al(a_N)Sib+(N-~ z) z- 2 wherein: the more fraction of aluminum, N, removed from the framework of the starting zeolite W is at least 0.3a;
the Si/Al has a value ~ 4, an increase in the Defect Structure Factor, ~ z, of less than 0.08, an increase of silicon in the framework N- z, of at least 0.5; a cation equivalent expressed as a monovalent cation species M+/Al of 0.9 ~ 0.1. Zeolite W and the method for its manufac-ture are set forth in U.S~P. 3,012,853 issued December 12, 1961.
The novel zeolites denominated LZ-217 ase the more 6iliceous forms of the prior known zeolite mineral offre-t~te and $ts 6ynthetic analogues, zeolite 0 and ~MA-~ffretite, and are prepared therefrom using the present process for 6ilicon 6ubstitut$0n. LZ-217 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides:
~7~837 12346-1 o g ~ 0.1 M2~nO : A1203 : x Si2 wherein M is a cation havin~ the valence "n" and "x"
has a value ~f at least 8 and the characteristic crystal structure of offretite as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table H, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetra-hedra, preferably in an amoun~ of at least 1.0 per 10,~0~.i3.
TABLE H
d(A) Relative Intensitv 11.4 + 0.2 Very Strong 6.6 + 0.1 Medium Strong 5.7 + 0.1 Medium Weak 4 31 + 0.1 Medium 3,75 + 0.1 Medium 3.58 + 0.1 Medium 3.29 + 0.1 Medium 3.14 + 0.1 Medium 2.84 ~ 0.1 Medium Strong 2.67 + 0.1 Medium Weak A more limited subclass of LZ-217 compositions, i.e.
those which are characterized by having both high molar S~02/A1203 ratios and low Defect Structure Factors, can be defined as having a chemical composition expressed in terms of mole fractions of framework tetrahedra as:
~Al(a_N)Sib+(N-~ ~z _702 1~7~37 12346-1 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite offretite is at least 0.3a; the Si/Al has a value ~4, an ir.cre~s~ in thL
Defect Structure Fact~r, ~z, of less than 0.08, an increase of silicon in the framework, ~-~z, of at least 0.5; a N
cation equivalent expressed as a monovalent cation s?~cies M /Al of 0.9 ~
The n~vel zeolites denominated LZ-218 are the more siliceous forms of the prior known zeolite mineral chaba-zite and the structurally related synthetic zeolite ~ zeolite G, and zeolite D, and are prepared therefrom using the present process for silicon substitution. LZ-218 has, in the tehydrated state, chemical composition expressed in terms of mole ratios of oxides:
o,g + 0 1 M2~nO : A1203 : x Si2 wherein M is a cation having the valence "n" and "x" has a value of greater than 8, preferably in the range of
[Al(a_N)Sib+(N-~ z) z- 2 wherein: the more fraction of aluminum, N, removed from the framework of the starting zeolite W is at least 0.3a;
the Si/Al has a value ~ 4, an increase in the Defect Structure Factor, ~ z, of less than 0.08, an increase of silicon in the framework N- z, of at least 0.5; a cation equivalent expressed as a monovalent cation species M+/Al of 0.9 ~ 0.1. Zeolite W and the method for its manufac-ture are set forth in U.S~P. 3,012,853 issued December 12, 1961.
The novel zeolites denominated LZ-217 ase the more 6iliceous forms of the prior known zeolite mineral offre-t~te and $ts 6ynthetic analogues, zeolite 0 and ~MA-~ffretite, and are prepared therefrom using the present process for 6ilicon 6ubstitut$0n. LZ-217 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides:
~7~837 12346-1 o g ~ 0.1 M2~nO : A1203 : x Si2 wherein M is a cation havin~ the valence "n" and "x"
has a value ~f at least 8 and the characteristic crystal structure of offretite as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table H, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetra-hedra, preferably in an amoun~ of at least 1.0 per 10,~0~.i3.
TABLE H
d(A) Relative Intensitv 11.4 + 0.2 Very Strong 6.6 + 0.1 Medium Strong 5.7 + 0.1 Medium Weak 4 31 + 0.1 Medium 3,75 + 0.1 Medium 3.58 + 0.1 Medium 3.29 + 0.1 Medium 3.14 + 0.1 Medium 2.84 ~ 0.1 Medium Strong 2.67 + 0.1 Medium Weak A more limited subclass of LZ-217 compositions, i.e.
those which are characterized by having both high molar S~02/A1203 ratios and low Defect Structure Factors, can be defined as having a chemical composition expressed in terms of mole fractions of framework tetrahedra as:
~Al(a_N)Sib+(N-~ ~z _702 1~7~37 12346-1 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite offretite is at least 0.3a; the Si/Al has a value ~4, an ir.cre~s~ in thL
Defect Structure Fact~r, ~z, of less than 0.08, an increase of silicon in the framework, ~-~z, of at least 0.5; a N
cation equivalent expressed as a monovalent cation s?~cies M /Al of 0.9 ~
The n~vel zeolites denominated LZ-218 are the more siliceous forms of the prior known zeolite mineral chaba-zite and the structurally related synthetic zeolite ~ zeolite G, and zeolite D, and are prepared therefrom using the present process for silicon substitution. LZ-218 has, in the tehydrated state, chemical composition expressed in terms of mole ratios of oxides:
o,g + 0 1 M2~nO : A1203 : x Si2 wherein M is a cation having the valence "n" and "x" has a value of greater than 8, preferably in the range of
8 to 20, and the characteristic crystal structure of chaba-zite as inticated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table I, below.
ant having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
.. . . . .
13 7~837 12346~1-c TA BLE
d(A) Relative IntensitY
ant having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
.. . . . .
13 7~837 12346~1-c TA BLE
d(A) Relative IntensitY
9.2 + 0.3 Very Stron~
6 .8 + O. 2 Medium 5.5 ~ 0.2 Medium 4.9 + 0.2 Medium 4.3 + 0.1 Very Strony 3.53 + 0.1 Medium 3.43 + 0.1 Medium 2.91 + 0.1 Medium Strong A more limited subclass of L2-218 compositions, i.e.
those which are characterized by having both higher molar SiO2/A12O3 ratios and low Defect Structure Factors, can ~e defined as having a chemical composition expressed in terms of mole fraction of framework tetrahedra as:
~Al(a_N)Sib+(N_aZ) z~2 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite is at least 0.3a; the ~i/Al has a value 34 an increase in the Defect Structure Factor, z, of less than 0.08, an increase of silicon in the framework, N~NZ of at least 0.5; a cation equivalent expressed as a monovalent cation s~e~-ies ~+/A1 of 0.9 + 0.1.
The novel zeolites denominated LZ-219 are the more siliceous æorms of the prior known zeolite mineral clinoptilolite, and are prepared therefrom using the present process for silicon substitution. LZ-219 has, in the dehydrated state a chemical composition expressed in terms of mole ratios of oxides:
''~1 1~7~37 12346-1-C
0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein M is a cation having the valence ~n" and "x" has a value of greater than 11, preferably in the range of 12 to 20, and the characteristic crystal structure of clinoptilolite as indicated by an X-ray powder dif~raction pattern having at least the d-spacings set forth in Table J, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA .
TA~LE I
d(A) Relative Intensity 8.9 + 0.2 Very Strong 7.B + 0.2 Medium 6.7 + 0.2 Medium Weak 6.6 + 0.2 Medium Weak -5.1 + 0.2 Medium Weak 3.95 + 0.1 Medium Strong 3.89 + 0.1 Medium 3.41 + 0.1 Medium 3.33 + 0.1 Medium 3.17 + 0.1 Medium A more limited subclass o~ LZ-219 compositions, i.e.
those which are characterized by having both higher molar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition, ex~ressed in terms of mole fraction of framework tetrahedra as:
[Al(a N)Slb+(N aZ)nZ ]2 ., ~. ~
13l7~837 wherein the mole fraction of aluminum removed, "N", from the starting clinoptilolite is at least 0.3a; a Si/Al ratio of ~5.5, preferably greater than 6.0, an increase in tne Defect Structure Factor, ~z of less than 0.08; an increase of silicon in the framework, ~ of at least 0.5, a cation equivalent expressed as a monovalent cation s~ecies ~+/Al o~ O . 9 + O . 1 .
The novel zeolites denominated LZ-220 are the core siliceous forms of the prior known mineral erionite and its synthetic analog, zeolite T, and are prepared therefrom using the present process for silicon substitution. LZ-220 has, in the dehydrated state a chemical composition expressed in terms of mole ratios of oxides:
o.g + 0.1 M2~nO : A12O3 x S 2 wherein M is a cation having the valence "n" and "x" has a value of at least 8, and preferably in the range of 8 to 20, and having the characteristic crystal structure of erionite as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table K, below, and having e~traneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
~A~LE K
d~A) Relative IntensitY
11.3 ~ 0.5 Very 6trong 6.6 ~ 0.2 Str~ng 4.33 ~ 0.1 Medium 3.82 ~ 0.1 Medium 3.76 ~ 0.1 Medium 3.31 ~ 0.1 ~edium 2.66 ~ 0.1 ~edium 2.81 ~ 0.1 Medium X
~ B37 12346-1-C
A more limited subclass of L~-220 compositions, i.e.
those which are characterized by having both high molar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition expressed in terms of mole fraction of framework tetrahedra as:
[Al(a-N)Sib+(N_~z)Ozlo2 wherein the mole fraction of aluminum, N, removed from the starting zeolite erionite, is at lease 0.3a; the Si/Al has a value S4,0 and preferably geeater than 5.0; an increase in the Defect Structure Factor, ~z, of less than 0.08, an increase or silicon in the framework N-~z of at least 0.5; a cation equivalent expressed as a monovalent cation species M+/Al of 0.9 + 0.1.
The novel zeolites denominated LZ-213 are the more siliceous forms of the prior known zeolite Omega and are prepared therefrom using the present process for silicon substitution. LZ-213 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein M is a cation having a valence "n" and "x" is a value greater than 20, preferably in the range of 22 to 60, and the characteristic crystal structure of zeolite Ome~a as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table ~, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per 10,000A3.
. ., . ~, 1~L7~37 TABLE L
d(A~ Relaeive Intensitv 15.8 + 0.4 Medium 9.1 1 0.2 Very Str~ng 7.9 + 0.2 Medlum 6.9 + 0.2 Medium 5.95 + 0.1 Medium 4.69 + 0.1 Medium 3.79 ~ 0.1 Very Strong 3.62 + 0.05 Medium 3.52 + 0.1 Medium A more limited subclass of LZ-213 compositions, i.e.
those which are characterized by having both high ~olar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition expressed in terms of mole fractions of framework tetrahedra as:
[Al(a-N)slb=(N-~z)oz~o2 wherein the mole fraction of aluminum, N, removed from the starting zeolite Omega is at least 0.3a; the Si/Al has value S10, and preferably in the range of 11 to 30 an increase in the Defect Structure Factor, ~z, of less than 0.08, an increase of silicon in the framework, ~ _ , of at lease 0.5; a cation equivalent expressed as a monovalent cation species ~+/Al of 0~9 + 0.1.
In general it is preferred that the cation equivalent of every novel composition of the present invention, expressed as a monovalent cation species M+/Al, is at least 0.8, and more preferably at least 0.85. With respect to those particular species herein which have been denominatea as "LZ" and a three digit number, the cation equivalent values speciried for _ 41 -~17~837 12346-1 each species subclass is also the preferred valu~ for the other members of the mor~ broadly defined members ~f each particular species.
The invention is illustrated by the procedures and products of the following examples:
ExamPle 1 .
(a) 396 grams of (NH4)2SiF6 were dissolved with stirrin~
in 3 liters of distilled water at 50C. This solution was put into a dropping funnel fitted on a three-necked round-bottom flask. A solution of 6400 grams of ammonium acetate in 8 liters of water was then added to the flask. An 85~' am~.,onium exchanged zeolite NaY in the amount of 1420 grams (hydrated weight, molar Si02/A1203 = 4.85) was slurried up in the ammonium acetate solution at 75C. A mechanical stirrer was fitted to the center hole of the flask, which was also fitted with the necessary thermocouples and tempera-ture controllers. Dropwise titration of the 3 liters of (NH4)2SiF6 solution was begun at 75C. ~fter completion of titration, which required a period of 2.5 hours, the pH
of the slurry was measured as 6Ø Overnight heating of the mixture was conducted at 95C, the dropping funnel having been replaced with a condenser. The stoichiometry of the reaction was of the order of one Si added as (NH4)2SiF6 for every two Al atoms present in the zeolite. At the conclusion of the reaction, the pH of the slurry was 6.75.
The reaction mixture was then filtered as two separate batches and the solids washed with 18 liters of hot distilled water. There was a residue of (NH4)3AlF6 present in the washed materials. An additional wash of the products in ammonium acetate was performed, followed by a thorough wash with boiling distilled H20 until ~.u~litative tests . .
12346-l 117~L837 could not detect either aluminum or fluoride ions in the effluent wash water.
The properties of this material were as follows:
Chemical Analysis:
comPosition By Wei~ht-~/O: Molar Composition Na20 0. 66 Na20/A1203 ~ 0. 08 (NH4~2 -6 . 50 (NH4) 20/A1203 ~ 0 . 91 A1203 ~13.97 Cation Equiva-lent = 0.99 SiO2 - 78.55 Cation Defi-ciencv = 1%
F - 0.02 F2/Al = 0.005 The product had the characteristic X-ray powder diffraction pattern of zeolite LZ-210 and had a unit cell dimension (aO) of 24.51 A. From peak intensity measure-ments, the crystallinity of the product was 94 percent.
The water adsorption capac~ty at 25C and 4.6 Torr was 28,7 weight-%. The oxygen atsorption capacity at -183C
and 100 Torr oxygen pressure was 29.3 weight-%. The crystal-collapse temperature of the product as measured by a stand-ard DTA procedure was at 1061C. Untreated NH4Y using the same DTA technique collap~es at 861C. The framework infrared spectra of the starting zeol~te ant the protuct zeolite are shown in Figure 1 of the trawings.
(b) Theprotuct of part (a) above was subjected to a mild ion exchange treatment with NaCl solution to replace most of the ammonium cations and then heated under vacuum at 200C for 1 hour to remove adsorbed (molecular) water, ant its hytroxyl infrared spectrum obtained. The spectrum, ~7~ 837 12346-l denoted as "A" in Fi~ure 2, shows a small broad absorption band with maximum absorbance at about 3300 cm l which is attributed to the residual undecomposed ammonium cations, two OH absorption bands at 3640 cm~l snd 3550 cm l attributed to OH groups produced by the decomposition of some of the residual ammonium cations, and a very small broad absorption band due to the hydroxyl "nests" in vacant framework sites in the zeolite. This absorption band is best obser~ed in the region of about 3710 - 3715 cm 1 when compared to the background absorption due to the zeolite.
Four hundred fifty gm of NaY containing 1.97 moles of aluminum as A1203 were slurried in 8 liters of distilled water with 287.7 gm of H4 EDTA (0.98 moles). The stirring slurry was refluxed for 18 hours, filtered washed and dried in air 2 hours at 110C. From the chemical analyses the product, Labled Defect Structure Standard, Sample A, was 48% depleted in aluminum. The calculated mole fraction of defects in the structure of Defect Structure Standard, Sample A,was 0.140. The framework composition expressed in terms of tetrahedral mole fractions (T02) was:
(Alo 15osio~71 ~ .140) 2 Spectrum B of Figure 2 is the spectrum of Defect Structure Standard, Sample A, from which 48% of the zeolite framework aluminum has been removed by extraction with H4 EDTA. The infrared sample was heated under vacuum at 200C for 1 hour to remove water. The spectrum shows the expected broad absorption band due to hydroxyl nests in vacant framework sites. In addition, there is a sharp absorption band at 3745 cm 1 attributed to terminal -SiOH
groups in ~he zeolite structure as previously discussed.
1~71~337 Similar bands are als~ observed with amorphous silica.
The spectra have been recorded in Figure 2 such that a nearly quantitati~e comparison can be made between the two samples. It becomes obvious then that the product of the (NH4)2SiF6 treatment of NH4Y, from which 50~/0 of the framework aluminum atoms have been removed, contains very few residual vacancies or hydroxyl nests in the framework.
It is even further obvious that the silicon taken up bv the zeolite during the (NH4)2SiF6 treatment must be substi-tuted into the previously vacant framework sites. No new absorption band at 3745 cm 1 due to amorphous -SiOH
is observed in this spectrum.
(c) The absolute absorbance of the Defect Structure Standard, Sample A, measured at 3710 cm 1 as in Figure 2 was 0.330. The absolute absorbance of the LZ-210 product of part (b) measured at 3710 cm 1 as in Figure 2 was 0.088.
The Defect Structure Factor, z, for the LZ-210 product was calculated:
rAbsolute Absorbance ~f the Unknown~ ~ole fraction o~
(unknown Z)' ~easured at 3710 cm J X defects in the ¦standard rAbsolutelAbsorbance of Standard measured at 3710 cm :_ Substituting into the equation, the defect structure factor for the LZ-210 product is 0.088 x 0.140; z = 0.037.
0.330 The framework composition of the LZ-210 product of part (b) of this Example can be expressed:
(Alo 167Sio~79 ~0.037)2 The framework composition of the starting NH4Y, used to prepare the LZ-210 product can be expressed (Alo 292Sio. 70~10)o2 , ~7183'7 12346-1 Comparing the LZ-210 product with the NH4Y starting material, the chan~e in Defect Structure Factor, ~z, is 0.037, well below the preferred maximum specification for LZ-210 of 0.05. The mole fraction of aluminum removed from the framework, N, is 0.125, which is substantially greater than the minimum specification that N ~0.3a. The increased silicon content of the framework of the LZ-210 product, expressed as a function of the removed aluminum actually replaced by silicon is:
-h-- ~ -125-0 037 0 70 Example 2 This example provides further proof that in the present process aluminum is removed from the zeolite framework and replaced in the framework by silicon from an extraneous source. Two grams (anhydrous weight) of ammonium zeolite Y (SiO2/A1203 molar ratio - 4.8) were slurried in 100 ml of 3.4 molar ammonium acetate solution at 75C. The total aluminum content of the zeolite sample was 8.90 millimoles.
A 50 ml solution containin~ 0.793 gm. (NH4)2SiF6 was added to the stirring slurry of the zeolite in 2 ml increments with 5 minutes between each addition. A total of 4.45 millimoles of Si was added to the zeolite. The mixture was kept at 75C for 18 hours, filtered and washed. Analysis of the filtrate and washin~s showed that of the 4.45 millimoles of silicon added, 3.4P. millimoles were consumed by the zeolite during the reaction. At the sametime, the zecl~te released 3.52 millimoles of aluminum to solution.
The molar SiO2/A1203 of the zeolite, based on the filtrate analysis was calculated to be 9.30. Chemical analysis of the solid product gave a SiO2/A1203 ratio of 9.31. These data prove conclusively that as a result of our treatment 1171~7 12346-l using buffered (NH4)2SiF6, silicon insertion had occurred.
From the peak intensity measurements, the product was 106 percent crystalline. The unit cell (aO) was 24.49 A.
The DTA exotherm denoting crystal collapse was found at 1037C. The intensity of the infrared OH absorption band measured at 3710 cm l following activation of the zeolite wafer at 200C attributable to (OH)4 ~roups in aluminum depleted sites was very small, indicatin~ that very few defect sites were present in the product. The oxygen adsorption capacity of the product measured at -183C and 100 Torr was 25.8 weight percent.
Exam~le 3 To a reaction vessel provided with heating and stirring means and containing 121.8 pounds (14.61 gal.) of water and 18.5 pounds of ammonium acetate was added 30 pounds (anhydrous basis) of 80% ammonium exchanged zeolite ~aY having a Si02/A1203 ~olar ratio of 4.97. The resulting slurry was heated to 75C. In a separate vessel an ammonium fluorosilicate r(NH4)2SiF6 ,7 solution was prepared by dissolving 12.25 pounds of the silicate in 46.8 pounds of water at a temperature of 50C. By means of a metering pump, the fluorosilicate solution was added to the buffered zeolite slurry at the rate of 0.031 gallons per minute.
About 3 hours was required to complete the addition. At the end of the addition period, the resultant mixture was heated to 95C with continuous agitation for a period of 16 hours, filtered, and washed with about 250 gallons of water at a temperature of 50C and dried. The product had the following properties:
.
1~71~37 12346-1-c (n) X-r~y cry6t~11inity (relative) ~ 90~.
(b) Tem~er~ture o~ cry~tal ~oll~pse (by DTA exotherm) 1110~C.
(c) Oxygen ~ds~rption capacity (-1839C, 100 torr) 26.1 wt.~.
(d) Water adsorption capacity (25C, 4.6 torr) ~ 24.5 wt .~
(e) SiO2/A1203 Qolar r~tio - 11.98.
(f) Zeolitic cation equivalence (~20/A1203) 1Ø
(9l Unit cell dimension, aO, ~ 24,~4 Angst~oms.
The framework composition of the starting NH4Y
expressed in terms of its molar fractions of tetrahedra can be stated thusly:
(Alo 286Sio.714) 2 The Defect Structure Factor, z, for the L2-210 product is 0.130. The framework composition of the LZ-210 product can be expressed as:
[Al(a_N)S1b+(N_~3)C z]2 The change in the Detect Structure Factor, ~z, for the LZ-210 is 0.055. The mole fraction of aluminum re~oved, N, is 0.151 and the amount of removed aluminum replaced by silicon is ~ O.64. All other characteristic properties of the modified zeolite compositions of this invention, i.e. X-ray powder diffraction pattern and infrared spectra were exhibited by the product of this example.
Example 4 (a) Forty-seven grams of NH4-Y containing 0.2065 moles of aluminum as A1203, were treated with ~NH4)2H2 EDTA and dilute HCl, sufficient to extract 43~ of the 1~7~37 framework aluminum in the NH4Y, over a period of 4 days in accordance with the tea.hir.gsand examplesofKerr in U.S. Patent 4,093,560. This was labled Sample B.
(b) Two thousand five hundred grams of NH4Y were stirred into 10 liters of 3.5 M ammonium acetate solution at 75C. A 3.5 liter solution of water containing 990 gr,,.
(NH4)2SiF6 was heated to 75C and added in 100 ml. incre-ments to the NH4Y slurry at the rate of 100 ml every 5 minutes. Following the addition of the fluorosilicate solution, the temperature of the slurry was raised to 95C and the slurry was digested at 95C for 17 hours. The digested slurry was filtered and the filter cake washed until tests of the wash water were negative for aluminum and fluoride ion. This was labled Sample C.
(c) The chemical and other analyses for the two samples are set forth below together with similar tata obtained on Defect Structure Standard, Sample A, prepared in (b) of Example 1.
- 4~ -~3l7~337 ~ O ~ v w ~ x ~ ~ s~ r c ~ ~o s' L- '~ 1 l \c~ V/ a~ v/ v~ ~ l v/ v ~n ~.
F ~ L ~ ~ ~- i 6 . L 3 ~ ~ n O O ~ ~ ~ O O D 3 L L L 3- ~ L L
~r r~O ~ 0 ~
1173 ~337 These data clearly distinguish the LZ-210 product (Sample C) from the prior art product (Sample B). Both Sample B and Sample C are aluminum depleted to ~he same level as the reference Defect Structure Standard (Sample A).
The prior art product shows no evidence that silicon from any source has substituted in the framework in place of the aluminum. In fact, the prior art sample and the reference Defect Structure Standard are nearly identical in all of their pr~perties. The LZ-210 product shows evidence of very little defect structure, indicating that in this case silicon has replaced aluminum in the frame-work.
Example 5 (A) One hundred grams of a well-crystallized zeolite Y having a molar Si02/A1203 ratio of 3.50 was slurried with 500 ml, of a 4 molar aqueous NH4Cl solution at reflux for one hour and then isolated by filtration. This exchange procedure was repeated twice, and the product of the third exchange washet with hot distillet water until tests of the wash water were negative for chloride ions. Sixty grams (anhydrous weight) of the NH4+ - exchanged product were slurried in 400 ml. of 3.4 molar ammonium acetate solution at 95C. A solution of 12.53 grams of ammonium fluorosilicate in 150 ml. of water was added to the slurry (pH 36) $n 1 ml. increments at the rate of 1 ml. per minute. The stoichiometric ratio of moles of Si, added as ammonium fluorosilicate ,to the moles of Al present in the zeolite was 0.21. Following the addition of the fluorosilicate solution, the slurry was digested for 3 hours at 95C., filtered, and the filter cake thoroughly washed until tests of the wash water were negative for ~L~lL7~L837 aluminum and the flu~ride ion. The chemical and other analyses for the starting NH4Y zeolite and the product zeolite are set forth below:
N~4-Y Product _ _ _ _ Na20 - wt.% 3.1 2.8 4 2 9.8 8.3 A123 wt. % 28.3 22.9 SiO2 wt.-% 58.2 65.2 SiO2/A1203 (molar) 3 50 4.84 Na tAl 0.18 0.20 ~H4 /Al 0.68 0.71 Cation Equiv. (M /Al) 0.86 0.91 X-ray Crystallinity;
(a) By Peak Intensity lO0 98 (b) By Peak Area 100 97 Unit cell timension (aO)24.81 24.734 Framework Infrared;
Asymmetric Stretch, cm 1891 1003 Symmetric Stretch, cm 1 771 782 Hydroxyl Infrared;
Absolute Abs. at 3710 cm 1 0.039 0.058 Defect Stfucture Factor, z 0.016 ~.~2' The framework mole fractions of tetrahedra are set forth below for the starting NH4Y and the LZ-210 product.
a) ~5O1e fraction of oxides (T02) - (Alo.358sio.626 0.016)2 (Alo 2RsSio 690 0.025) 2 b) Mole fraction of aluminum removed, N - 0.073 c) % aluminum removed, n/a x 100 - 20 t) change in defect structure factor,~z - 0.009 e) moles of silicon substituted per mole of aluminum removed,N-~z 0.88 _ ~, _ 1173 ~37 The analytical data show conslusively that framework aluminum was removed and replaced by silicon as a res~lt of the fluorosilicate treatment. The X-ray crystallinity was fully maintained and the unit cell dimension decreased as would be expected due to the smaller atomic size Df silicon with respect to aluminum.
(B) The adverse effects of using a startin~ zeolite having a molar Si02/Al203 ratio of less than 3 is demon-strated by the following procedure:
One hundred grams of an ammonium-exchanged zeolite X
having a molar Si02/A1203 ratio of 2.52 were slurried in 1000 ml. of an aqueous 2.0 molar solution of ammonium acetate at a temperature of 75C. Five hundred milli-liters of a second aqueous solution containing 59.75 grams of ammonium fluorosilicate was added to the slurry in
6 .8 + O. 2 Medium 5.5 ~ 0.2 Medium 4.9 + 0.2 Medium 4.3 + 0.1 Very Strony 3.53 + 0.1 Medium 3.43 + 0.1 Medium 2.91 + 0.1 Medium Strong A more limited subclass of L2-218 compositions, i.e.
those which are characterized by having both higher molar SiO2/A12O3 ratios and low Defect Structure Factors, can ~e defined as having a chemical composition expressed in terms of mole fraction of framework tetrahedra as:
~Al(a_N)Sib+(N_aZ) z~2 wherein: the mole fraction of aluminum, N, removed from the framework of the starting zeolite is at least 0.3a; the ~i/Al has a value 34 an increase in the Defect Structure Factor, z, of less than 0.08, an increase of silicon in the framework, N~NZ of at least 0.5; a cation equivalent expressed as a monovalent cation s~e~-ies ~+/A1 of 0.9 + 0.1.
The novel zeolites denominated LZ-219 are the more siliceous æorms of the prior known zeolite mineral clinoptilolite, and are prepared therefrom using the present process for silicon substitution. LZ-219 has, in the dehydrated state a chemical composition expressed in terms of mole ratios of oxides:
''~1 1~7~37 12346-1-C
0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein M is a cation having the valence ~n" and "x" has a value of greater than 11, preferably in the range of 12 to 20, and the characteristic crystal structure of clinoptilolite as indicated by an X-ray powder dif~raction pattern having at least the d-spacings set forth in Table J, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA .
TA~LE I
d(A) Relative Intensity 8.9 + 0.2 Very Strong 7.B + 0.2 Medium 6.7 + 0.2 Medium Weak 6.6 + 0.2 Medium Weak -5.1 + 0.2 Medium Weak 3.95 + 0.1 Medium Strong 3.89 + 0.1 Medium 3.41 + 0.1 Medium 3.33 + 0.1 Medium 3.17 + 0.1 Medium A more limited subclass o~ LZ-219 compositions, i.e.
those which are characterized by having both higher molar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition, ex~ressed in terms of mole fraction of framework tetrahedra as:
[Al(a N)Slb+(N aZ)nZ ]2 ., ~. ~
13l7~837 wherein the mole fraction of aluminum removed, "N", from the starting clinoptilolite is at least 0.3a; a Si/Al ratio of ~5.5, preferably greater than 6.0, an increase in tne Defect Structure Factor, ~z of less than 0.08; an increase of silicon in the framework, ~ of at least 0.5, a cation equivalent expressed as a monovalent cation s~ecies ~+/Al o~ O . 9 + O . 1 .
The novel zeolites denominated LZ-220 are the core siliceous forms of the prior known mineral erionite and its synthetic analog, zeolite T, and are prepared therefrom using the present process for silicon substitution. LZ-220 has, in the dehydrated state a chemical composition expressed in terms of mole ratios of oxides:
o.g + 0.1 M2~nO : A12O3 x S 2 wherein M is a cation having the valence "n" and "x" has a value of at least 8, and preferably in the range of 8 to 20, and having the characteristic crystal structure of erionite as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table K, below, and having e~traneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per lO,OOOA3.
~A~LE K
d~A) Relative IntensitY
11.3 ~ 0.5 Very 6trong 6.6 ~ 0.2 Str~ng 4.33 ~ 0.1 Medium 3.82 ~ 0.1 Medium 3.76 ~ 0.1 Medium 3.31 ~ 0.1 ~edium 2.66 ~ 0.1 ~edium 2.81 ~ 0.1 Medium X
~ B37 12346-1-C
A more limited subclass of L~-220 compositions, i.e.
those which are characterized by having both high molar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition expressed in terms of mole fraction of framework tetrahedra as:
[Al(a-N)Sib+(N_~z)Ozlo2 wherein the mole fraction of aluminum, N, removed from the starting zeolite erionite, is at lease 0.3a; the Si/Al has a value S4,0 and preferably geeater than 5.0; an increase in the Defect Structure Factor, ~z, of less than 0.08, an increase or silicon in the framework N-~z of at least 0.5; a cation equivalent expressed as a monovalent cation species M+/Al of 0.9 + 0.1.
The novel zeolites denominated LZ-213 are the more siliceous forms of the prior known zeolite Omega and are prepared therefrom using the present process for silicon substitution. LZ-213 has, in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 + 0.1 M2/nO : A12O3 : x SiO2 wherein M is a cation having a valence "n" and "x" is a value greater than 20, preferably in the range of 22 to 60, and the characteristic crystal structure of zeolite Ome~a as indicated by an X-ray powder diffraction pattern having at least the d-spacings set forth in Table ~, below, and having extraneous silicon atoms in its crystal lattice in the form of SiO4 tetrahedra, preferably in an amount of at least 1.0 per 10,000A3.
. ., . ~, 1~L7~37 TABLE L
d(A~ Relaeive Intensitv 15.8 + 0.4 Medium 9.1 1 0.2 Very Str~ng 7.9 + 0.2 Medlum 6.9 + 0.2 Medium 5.95 + 0.1 Medium 4.69 + 0.1 Medium 3.79 ~ 0.1 Very Strong 3.62 + 0.05 Medium 3.52 + 0.1 Medium A more limited subclass of LZ-213 compositions, i.e.
those which are characterized by having both high ~olar SiO2/A12O3 ratios and low Defect Structure Factors, can be defined as having a chemical composition expressed in terms of mole fractions of framework tetrahedra as:
[Al(a-N)slb=(N-~z)oz~o2 wherein the mole fraction of aluminum, N, removed from the starting zeolite Omega is at least 0.3a; the Si/Al has value S10, and preferably in the range of 11 to 30 an increase in the Defect Structure Factor, ~z, of less than 0.08, an increase of silicon in the framework, ~ _ , of at lease 0.5; a cation equivalent expressed as a monovalent cation species ~+/Al of 0~9 + 0.1.
In general it is preferred that the cation equivalent of every novel composition of the present invention, expressed as a monovalent cation species M+/Al, is at least 0.8, and more preferably at least 0.85. With respect to those particular species herein which have been denominatea as "LZ" and a three digit number, the cation equivalent values speciried for _ 41 -~17~837 12346-1 each species subclass is also the preferred valu~ for the other members of the mor~ broadly defined members ~f each particular species.
The invention is illustrated by the procedures and products of the following examples:
ExamPle 1 .
(a) 396 grams of (NH4)2SiF6 were dissolved with stirrin~
in 3 liters of distilled water at 50C. This solution was put into a dropping funnel fitted on a three-necked round-bottom flask. A solution of 6400 grams of ammonium acetate in 8 liters of water was then added to the flask. An 85~' am~.,onium exchanged zeolite NaY in the amount of 1420 grams (hydrated weight, molar Si02/A1203 = 4.85) was slurried up in the ammonium acetate solution at 75C. A mechanical stirrer was fitted to the center hole of the flask, which was also fitted with the necessary thermocouples and tempera-ture controllers. Dropwise titration of the 3 liters of (NH4)2SiF6 solution was begun at 75C. ~fter completion of titration, which required a period of 2.5 hours, the pH
of the slurry was measured as 6Ø Overnight heating of the mixture was conducted at 95C, the dropping funnel having been replaced with a condenser. The stoichiometry of the reaction was of the order of one Si added as (NH4)2SiF6 for every two Al atoms present in the zeolite. At the conclusion of the reaction, the pH of the slurry was 6.75.
The reaction mixture was then filtered as two separate batches and the solids washed with 18 liters of hot distilled water. There was a residue of (NH4)3AlF6 present in the washed materials. An additional wash of the products in ammonium acetate was performed, followed by a thorough wash with boiling distilled H20 until ~.u~litative tests . .
12346-l 117~L837 could not detect either aluminum or fluoride ions in the effluent wash water.
The properties of this material were as follows:
Chemical Analysis:
comPosition By Wei~ht-~/O: Molar Composition Na20 0. 66 Na20/A1203 ~ 0. 08 (NH4~2 -6 . 50 (NH4) 20/A1203 ~ 0 . 91 A1203 ~13.97 Cation Equiva-lent = 0.99 SiO2 - 78.55 Cation Defi-ciencv = 1%
F - 0.02 F2/Al = 0.005 The product had the characteristic X-ray powder diffraction pattern of zeolite LZ-210 and had a unit cell dimension (aO) of 24.51 A. From peak intensity measure-ments, the crystallinity of the product was 94 percent.
The water adsorption capac~ty at 25C and 4.6 Torr was 28,7 weight-%. The oxygen atsorption capacity at -183C
and 100 Torr oxygen pressure was 29.3 weight-%. The crystal-collapse temperature of the product as measured by a stand-ard DTA procedure was at 1061C. Untreated NH4Y using the same DTA technique collap~es at 861C. The framework infrared spectra of the starting zeol~te ant the protuct zeolite are shown in Figure 1 of the trawings.
(b) Theprotuct of part (a) above was subjected to a mild ion exchange treatment with NaCl solution to replace most of the ammonium cations and then heated under vacuum at 200C for 1 hour to remove adsorbed (molecular) water, ant its hytroxyl infrared spectrum obtained. The spectrum, ~7~ 837 12346-l denoted as "A" in Fi~ure 2, shows a small broad absorption band with maximum absorbance at about 3300 cm l which is attributed to the residual undecomposed ammonium cations, two OH absorption bands at 3640 cm~l snd 3550 cm l attributed to OH groups produced by the decomposition of some of the residual ammonium cations, and a very small broad absorption band due to the hydroxyl "nests" in vacant framework sites in the zeolite. This absorption band is best obser~ed in the region of about 3710 - 3715 cm 1 when compared to the background absorption due to the zeolite.
Four hundred fifty gm of NaY containing 1.97 moles of aluminum as A1203 were slurried in 8 liters of distilled water with 287.7 gm of H4 EDTA (0.98 moles). The stirring slurry was refluxed for 18 hours, filtered washed and dried in air 2 hours at 110C. From the chemical analyses the product, Labled Defect Structure Standard, Sample A, was 48% depleted in aluminum. The calculated mole fraction of defects in the structure of Defect Structure Standard, Sample A,was 0.140. The framework composition expressed in terms of tetrahedral mole fractions (T02) was:
(Alo 15osio~71 ~ .140) 2 Spectrum B of Figure 2 is the spectrum of Defect Structure Standard, Sample A, from which 48% of the zeolite framework aluminum has been removed by extraction with H4 EDTA. The infrared sample was heated under vacuum at 200C for 1 hour to remove water. The spectrum shows the expected broad absorption band due to hydroxyl nests in vacant framework sites. In addition, there is a sharp absorption band at 3745 cm 1 attributed to terminal -SiOH
groups in ~he zeolite structure as previously discussed.
1~71~337 Similar bands are als~ observed with amorphous silica.
The spectra have been recorded in Figure 2 such that a nearly quantitati~e comparison can be made between the two samples. It becomes obvious then that the product of the (NH4)2SiF6 treatment of NH4Y, from which 50~/0 of the framework aluminum atoms have been removed, contains very few residual vacancies or hydroxyl nests in the framework.
It is even further obvious that the silicon taken up bv the zeolite during the (NH4)2SiF6 treatment must be substi-tuted into the previously vacant framework sites. No new absorption band at 3745 cm 1 due to amorphous -SiOH
is observed in this spectrum.
(c) The absolute absorbance of the Defect Structure Standard, Sample A, measured at 3710 cm 1 as in Figure 2 was 0.330. The absolute absorbance of the LZ-210 product of part (b) measured at 3710 cm 1 as in Figure 2 was 0.088.
The Defect Structure Factor, z, for the LZ-210 product was calculated:
rAbsolute Absorbance ~f the Unknown~ ~ole fraction o~
(unknown Z)' ~easured at 3710 cm J X defects in the ¦standard rAbsolutelAbsorbance of Standard measured at 3710 cm :_ Substituting into the equation, the defect structure factor for the LZ-210 product is 0.088 x 0.140; z = 0.037.
0.330 The framework composition of the LZ-210 product of part (b) of this Example can be expressed:
(Alo 167Sio~79 ~0.037)2 The framework composition of the starting NH4Y, used to prepare the LZ-210 product can be expressed (Alo 292Sio. 70~10)o2 , ~7183'7 12346-1 Comparing the LZ-210 product with the NH4Y starting material, the chan~e in Defect Structure Factor, ~z, is 0.037, well below the preferred maximum specification for LZ-210 of 0.05. The mole fraction of aluminum removed from the framework, N, is 0.125, which is substantially greater than the minimum specification that N ~0.3a. The increased silicon content of the framework of the LZ-210 product, expressed as a function of the removed aluminum actually replaced by silicon is:
-h-- ~ -125-0 037 0 70 Example 2 This example provides further proof that in the present process aluminum is removed from the zeolite framework and replaced in the framework by silicon from an extraneous source. Two grams (anhydrous weight) of ammonium zeolite Y (SiO2/A1203 molar ratio - 4.8) were slurried in 100 ml of 3.4 molar ammonium acetate solution at 75C. The total aluminum content of the zeolite sample was 8.90 millimoles.
A 50 ml solution containin~ 0.793 gm. (NH4)2SiF6 was added to the stirring slurry of the zeolite in 2 ml increments with 5 minutes between each addition. A total of 4.45 millimoles of Si was added to the zeolite. The mixture was kept at 75C for 18 hours, filtered and washed. Analysis of the filtrate and washin~s showed that of the 4.45 millimoles of silicon added, 3.4P. millimoles were consumed by the zeolite during the reaction. At the sametime, the zecl~te released 3.52 millimoles of aluminum to solution.
The molar SiO2/A1203 of the zeolite, based on the filtrate analysis was calculated to be 9.30. Chemical analysis of the solid product gave a SiO2/A1203 ratio of 9.31. These data prove conclusively that as a result of our treatment 1171~7 12346-l using buffered (NH4)2SiF6, silicon insertion had occurred.
From the peak intensity measurements, the product was 106 percent crystalline. The unit cell (aO) was 24.49 A.
The DTA exotherm denoting crystal collapse was found at 1037C. The intensity of the infrared OH absorption band measured at 3710 cm l following activation of the zeolite wafer at 200C attributable to (OH)4 ~roups in aluminum depleted sites was very small, indicatin~ that very few defect sites were present in the product. The oxygen adsorption capacity of the product measured at -183C and 100 Torr was 25.8 weight percent.
Exam~le 3 To a reaction vessel provided with heating and stirring means and containing 121.8 pounds (14.61 gal.) of water and 18.5 pounds of ammonium acetate was added 30 pounds (anhydrous basis) of 80% ammonium exchanged zeolite ~aY having a Si02/A1203 ~olar ratio of 4.97. The resulting slurry was heated to 75C. In a separate vessel an ammonium fluorosilicate r(NH4)2SiF6 ,7 solution was prepared by dissolving 12.25 pounds of the silicate in 46.8 pounds of water at a temperature of 50C. By means of a metering pump, the fluorosilicate solution was added to the buffered zeolite slurry at the rate of 0.031 gallons per minute.
About 3 hours was required to complete the addition. At the end of the addition period, the resultant mixture was heated to 95C with continuous agitation for a period of 16 hours, filtered, and washed with about 250 gallons of water at a temperature of 50C and dried. The product had the following properties:
.
1~71~37 12346-1-c (n) X-r~y cry6t~11inity (relative) ~ 90~.
(b) Tem~er~ture o~ cry~tal ~oll~pse (by DTA exotherm) 1110~C.
(c) Oxygen ~ds~rption capacity (-1839C, 100 torr) 26.1 wt.~.
(d) Water adsorption capacity (25C, 4.6 torr) ~ 24.5 wt .~
(e) SiO2/A1203 Qolar r~tio - 11.98.
(f) Zeolitic cation equivalence (~20/A1203) 1Ø
(9l Unit cell dimension, aO, ~ 24,~4 Angst~oms.
The framework composition of the starting NH4Y
expressed in terms of its molar fractions of tetrahedra can be stated thusly:
(Alo 286Sio.714) 2 The Defect Structure Factor, z, for the L2-210 product is 0.130. The framework composition of the LZ-210 product can be expressed as:
[Al(a_N)S1b+(N_~3)C z]2 The change in the Detect Structure Factor, ~z, for the LZ-210 is 0.055. The mole fraction of aluminum re~oved, N, is 0.151 and the amount of removed aluminum replaced by silicon is ~ O.64. All other characteristic properties of the modified zeolite compositions of this invention, i.e. X-ray powder diffraction pattern and infrared spectra were exhibited by the product of this example.
Example 4 (a) Forty-seven grams of NH4-Y containing 0.2065 moles of aluminum as A1203, were treated with ~NH4)2H2 EDTA and dilute HCl, sufficient to extract 43~ of the 1~7~37 framework aluminum in the NH4Y, over a period of 4 days in accordance with the tea.hir.gsand examplesofKerr in U.S. Patent 4,093,560. This was labled Sample B.
(b) Two thousand five hundred grams of NH4Y were stirred into 10 liters of 3.5 M ammonium acetate solution at 75C. A 3.5 liter solution of water containing 990 gr,,.
(NH4)2SiF6 was heated to 75C and added in 100 ml. incre-ments to the NH4Y slurry at the rate of 100 ml every 5 minutes. Following the addition of the fluorosilicate solution, the temperature of the slurry was raised to 95C and the slurry was digested at 95C for 17 hours. The digested slurry was filtered and the filter cake washed until tests of the wash water were negative for aluminum and fluoride ion. This was labled Sample C.
(c) The chemical and other analyses for the two samples are set forth below together with similar tata obtained on Defect Structure Standard, Sample A, prepared in (b) of Example 1.
- 4~ -~3l7~337 ~ O ~ v w ~ x ~ ~ s~ r c ~ ~o s' L- '~ 1 l \c~ V/ a~ v/ v~ ~ l v/ v ~n ~.
F ~ L ~ ~ ~- i 6 . L 3 ~ ~ n O O ~ ~ ~ O O D 3 L L L 3- ~ L L
~r r~O ~ 0 ~
1173 ~337 These data clearly distinguish the LZ-210 product (Sample C) from the prior art product (Sample B). Both Sample B and Sample C are aluminum depleted to ~he same level as the reference Defect Structure Standard (Sample A).
The prior art product shows no evidence that silicon from any source has substituted in the framework in place of the aluminum. In fact, the prior art sample and the reference Defect Structure Standard are nearly identical in all of their pr~perties. The LZ-210 product shows evidence of very little defect structure, indicating that in this case silicon has replaced aluminum in the frame-work.
Example 5 (A) One hundred grams of a well-crystallized zeolite Y having a molar Si02/A1203 ratio of 3.50 was slurried with 500 ml, of a 4 molar aqueous NH4Cl solution at reflux for one hour and then isolated by filtration. This exchange procedure was repeated twice, and the product of the third exchange washet with hot distillet water until tests of the wash water were negative for chloride ions. Sixty grams (anhydrous weight) of the NH4+ - exchanged product were slurried in 400 ml. of 3.4 molar ammonium acetate solution at 95C. A solution of 12.53 grams of ammonium fluorosilicate in 150 ml. of water was added to the slurry (pH 36) $n 1 ml. increments at the rate of 1 ml. per minute. The stoichiometric ratio of moles of Si, added as ammonium fluorosilicate ,to the moles of Al present in the zeolite was 0.21. Following the addition of the fluorosilicate solution, the slurry was digested for 3 hours at 95C., filtered, and the filter cake thoroughly washed until tests of the wash water were negative for ~L~lL7~L837 aluminum and the flu~ride ion. The chemical and other analyses for the starting NH4Y zeolite and the product zeolite are set forth below:
N~4-Y Product _ _ _ _ Na20 - wt.% 3.1 2.8 4 2 9.8 8.3 A123 wt. % 28.3 22.9 SiO2 wt.-% 58.2 65.2 SiO2/A1203 (molar) 3 50 4.84 Na tAl 0.18 0.20 ~H4 /Al 0.68 0.71 Cation Equiv. (M /Al) 0.86 0.91 X-ray Crystallinity;
(a) By Peak Intensity lO0 98 (b) By Peak Area 100 97 Unit cell timension (aO)24.81 24.734 Framework Infrared;
Asymmetric Stretch, cm 1891 1003 Symmetric Stretch, cm 1 771 782 Hydroxyl Infrared;
Absolute Abs. at 3710 cm 1 0.039 0.058 Defect Stfucture Factor, z 0.016 ~.~2' The framework mole fractions of tetrahedra are set forth below for the starting NH4Y and the LZ-210 product.
a) ~5O1e fraction of oxides (T02) - (Alo.358sio.626 0.016)2 (Alo 2RsSio 690 0.025) 2 b) Mole fraction of aluminum removed, N - 0.073 c) % aluminum removed, n/a x 100 - 20 t) change in defect structure factor,~z - 0.009 e) moles of silicon substituted per mole of aluminum removed,N-~z 0.88 _ ~, _ 1173 ~37 The analytical data show conslusively that framework aluminum was removed and replaced by silicon as a res~lt of the fluorosilicate treatment. The X-ray crystallinity was fully maintained and the unit cell dimension decreased as would be expected due to the smaller atomic size Df silicon with respect to aluminum.
(B) The adverse effects of using a startin~ zeolite having a molar Si02/Al203 ratio of less than 3 is demon-strated by the following procedure:
One hundred grams of an ammonium-exchanged zeolite X
having a molar Si02/A1203 ratio of 2.52 were slurried in 1000 ml. of an aqueous 2.0 molar solution of ammonium acetate at a temperature of 75C. Five hundred milli-liters of a second aqueous solution containing 59.75 grams of ammonium fluorosilicate was added to the slurry in
10 ml. increments st a rate of 10 ml. every 5 minutes.
The stoichiometric ratio of moles of silicon added to the moles of aluminum present in the zeolite was 0.50. Follow-ing the adtition of the fluorosilicate solution, the slurry was digested for 16 hours at 95C, filtered, and washed with distilled water until tests of the wash water were negative for both aluminum and fluoride ions. The chemical and other analyses for the starting NH4-X zeolite and the product zeolite are set forth below:
1~7~837 NH4-X Product Na20 - wt.~/o 3.2 0.5 (NH4)20 ~ wt.% 10.8 6.5 l2o3 wt.% 34.2 l9.t) SiO2 - wt.% 50.8 72.0 SiO2/A1203 (molar) 2.52 6 . ~3 Na /Al 0.15 0.04 NH +/Al 0. 62 0 . 67 Cation Equivalent (M /Al) 0.77 0.71 X-ray Crystallinity;
(a) by Peak Intensity 100 clO
Unit cell dimension (aO),A.24.945 __ Framework Infrared:
(a) Asymmetric Stretch, cm l 987 1049 (b) Symmetric Srretch, cm 1 749 780 Hydroxyl Infrared;
Absolute Abs. at 3710 cm l0.110 U.224 Defect Structure Factor, z 0.047 0.095 It is apparent from the foregoing data that although dealumination in conjunction with silicon substitution into the zeolite framework did occur, the procedure was highly destructive of the crystallinity of the product zeolite. Also the remaining crystal structure contained an undue number of defect site.
(C) In a second attempt to treat the NH4-X of part (B), a 5 gram sample of the zeolite was slurried in 100 ml. of a 3.4 molar ammonium acetate solution at 95C.
Fifty milliliters of a second aqueous solution containing 1.49 grams of ammonium fluorosilicate was added to the slurry in 2 ml. incremen~s at a rate of 2 ml. every five minutes. The stoichiometric ratio of moles of silicon 12346-l added to the moles of zeolitic aluminum was 0.25. Follo~-ing the completion ofthe addition of the fluorosilicate solution, the slurry was digested for 3 hours, filtered and washed. Although the treatment of this part (C) was much less rigorous than that of part (B) above by v~reue of increased buffering, lower fluorosilicate concentration and shorter digestion time, the product of part (C) was found to be nearly amorphous.
Example 6 ~ he process for substituting extraneous silicon for framework aluminum atoms in a zeolite having the zeoli~e A-type structure is illustrated by the following experi-mental procedure: Approximately S grams of zeolite N-A
(prepared hydrothermally using a combination of sodium hydroxide and tetramethylammonium hydroxide in accordance with the teachings of U.S.P. 3,305,922) having a SiO2/
A1203 molar ratio of 6.0 was calcined in air at 550C
for 17 hours to remove the tetramethylammonlum cations.
The resulting decationized form of the zeolite was ion-exchanged with an aqueous solution of NH4Cl. A twelve gram (anhyd.) sample of the resulting NH4-A zeolite was slurried ~n 300 ml. of an aqueous 3.4 molar ammonium acetate solution at 75C and 100 ml. of an aqueous solution containing 4.63 gm. ammonium fluorosilicate was added thereto in 1 ml. increments at the rate of l ml. per minute. Following completionof the addition of the fluoro-silicate solution, the slurry was digested for 16 hours at 75C filtered, and the solids then tho,oughly washed with water. The preliminary decationization and 1~ 7~837 subsequent rehydration of the starting zeolite introduced a considerable number of defect sites into the zeolite starting material which were not, under the conditions employed in the fluorosilicate treatment, filled by silicon insertion. The observed decrease in the unit cell dimension, aO, from 11.994 to 11.970, however, establishes that extraneous silicon from the fluorosilicate was substituted for original framework aluminum atoms in the zeolite. The results of chemical and other analyses for the starting NH4-NA and the LZ-215 product zeolite are set forth below:
NH4-NA LZ-215 Product Si02/A1203 (molar) 5-43 7.38 Cation Equivalent, (M /Al) 0.65 0.69 X-Ray Crystallinity: .
(a) % by Peak Intensity 100 60 (b) % by Peak Area 100 59 Unit Cell Dimension (aO) 11.994 11.970 Framework Infrared:
asymmetric Stretch, cm 1 1062 1069 symmetric Stretch, cm 1 713 722 Hydroxyl Infrared:
Defect Structure Factor (z)0.042 0.079 Absolute Absorbance at 3710 cm~l 0.100 0.186 The framework mole fractions of tetrahedra are set forth below for the starting NH4-NA and the LZ-215 product.
a) Mole fraction of oxides (T02) - (Alo 2S8Sio 700r~o 042)2 (Alo 196sio.725 0.079)2 b) Mole fraction of aluminum removed,N - 0.062 c) % aluminum removed, N/a x 100 - 24 d) Change in defect structure factor , ~z,- 0.037 e) Moles of silicon substituted per mole of aluminum removed, (~-~z)/N _ 0.40 ~171837 In order to prepare a high silica zeolite of the type-A structure which is substantially free of defect sites it is necessary either to maintain the organic cations in the starting zeolite or to thermally degrade the organic cations to NH4+ or H+ cations under controlled conditions such as minimal decomposition temperatures and in an environment of nitrogen and/or ammonia.
Example 7 (A) The substitution of extraneous silicon into the crystal lattice of a zeolite of the mordenite type is illustrated by this example in which a commercially avail-able synthetic acid-treated mordenite was used as the starting material. One thousand grams of the synthetic mordenite (SiO2/A1203 = 11.67) were slurried in 8 liters of distilled water at reflux temperature. Three liters of an aqueous solution containlng 435 grams of ammonium fluorosilicate was added rapidly to the zeolite-water slurry and the resultant mixture refluxed with stirring for 96 hours. The zeolite product was then isolated by filtration and washed with distilled water. The chemical and other analyses results are set forth below for the starting material and the product zeolite.
B
12346-l 1~7~837 H-Zeolon LZ-211 _ Product Na20, wt.-% 0.48 0.32 (NH4)20, wt.-% __ 1.65 A1203, wt.-% 12.44 6.48 SiO2, wt.-% 85.51 91.88 SiO2/Al203(molar) 11.6' 24.08 Na /Al 0.05 0.08 N~4 /Al __ 0 50 Cation Equivalent, M /Al 0.06 0.58 X ray Crystallinity by Peak Intensity 100 85 Fra~ework Infrared:
Asymmetric Stretch, cmll 1070 1093 Symmetric Stretch, cm 801 811 Hydroxyl Infrared:
Absolute Abs. at 3710 cm 0.185 0.245 Defect Structure Factor, z 0.078 0.104 Since the starting H-2eolon contained a substantial number of defect sites, it is not necessary that the process substitute silicon into those tefect sites. The fact that the process of this invention does not create any substan-tial amount of new defects in the structure is substantiated by the fact that the Defect Structure Factor, "z", increased by only 0.026 as a result of the treatment.
The framework mole fractions of tetrahedra are shown below for the starting H-Zeolon and the LZ-211 Product.
a) Mole fraction of oxides ~TO2) H-Zeolon - (Alo.l34si0.787r0.078 2 LZ-211 - (Alo 069Sio,827 0~lo4~o2 b) Mole fraction of aluminum removed, N - 0.065 c) % Aluminum Removed, N/a x 100 - 49 12346-l 13L7~L~337 d) Change in Defect Structure Factor,~z - 0.026 e) Moles of silicon substituted per mole of aluminum removed, N-~z - 0.60 N
These data show quite conclusively that aluminum has been removed from the structure and replaced with ~ilicon as a result of the fluorosilicate treatment. It is also apparent that the treatment conditions, particularly the rapid addition of the fluorosilicate solution to the zeolite, did not permit the insertion of silicon into all of the sites from which aluminum was removed during the treatment or into all of the aluminum depleted sites of the original H-Zeolon starting material. On the other hand, X-ray crystallinity was maintained, and while no exotherm due to crystal collapse was observed in either sample in differen-tial thermal analyses, sintering began at about 1000C in the starting zeolite but did not occur ùntil about 1150C
in the product zeolite. The framework infrared spectra show shifts to higher wavenumbers following fluorosilicate treatment. The shift of both the asymmetric stretch band and the symmet~ic stretch band is characteristic of dealumina-tion accompan$ed by silicon substitution in the framework.
In the hydroxyl region of the infrared spectrum of the fluorosilicate treated zeolite there was no increase in the 3745 cm 1 band tue to occluded amorphous Si~H. There was only a small increase in absorbance at 3710 cm 1 compared to the starting H-Zeolon indicating that there was only a small increase in the number of framework vacancies due to the treatment. It is to be noted, however, that moderating the severity of the treatment as illustrated in part (B) of the Example, below, results not only in the substantial replacement of aluminum atoms removed during the treatment, but also considerable filling of aluminum-vacant sites in . . .
.
~7~.~337 12346 l the starting zeolite.
(B) In another example, 2500 grams of a similar H-Zeolon starting materi~l as employed in part (A) was stirred in 5 liters of distilled water at 95C. A second solution of 5 liters of distilled water containing 3B2.7 grams of ammonium fluorosilicate at a temperature of about 75C was added directiy to the zeolite-water slurry at a rate of about 50-100 ml. per minute. During the addition period the temperature was maintained at 95C. The stoi-chiometric ratio of moles of silicon added to the moles of aluminum present in the zeolite was 0.41. Follow comple-tion of the addition ofthe fluorosilicate solution, the slurry was digested for 72 hours under reflux conditions, the solids recovered by filtration, and washed with distilled water. The chemical and other analyses results are set iorth below: LZ-211 H-Zeolon _ Prod~ct Na20, wt.-% 0.2 0.2 (L~H4)20, wt,-% __ 2.1 A1203, wt.-% 10.8 5.7 SiO2, wt.-% 88.8 9~.4 S~02/A1203 (molar~ 14.00 24.12 ~a /Al .0 03 0,04 ~H4 /Al -- 0.72 Cation Eauivalent, M /Al 0.03 .~0.76 X-ray Crystallinity:
ta) by Peak Intensity 100 86 (b) by Peak Area 100 90 Fra~ework Infrared:
Asymmetric Stretch, cm 1 1073 1089 Symmetric Stretch, cm 1 801 815 Hydroxyl Infraret:
Absolute Abs. at 3710 cm 1 0.325 0.115 Defect Structure Factor, z 0.137 0.048 1~71837 In this example, the defect structure factor of the starting H-Zeolon is quite large. As a resul~ of the treatment it would appear that a substantial number of the ori~inal defect sites have been eliminated. The framework mole fractions are set forth below for the start-ing H-Ze~lon and the LZ-211 product a) Mole fraction of oxides(TO~ H-Zeolon (Alo 108Sio 755r-0 137) LZ-211 (Alo 073SiO.879 0.048) b) Mole fraction of aluminum removed,~l - o.n35 c) % Aluminum tepletion, N/a x 100 - 32 c) Change in defect structure,~ z - -O.089 From the data it is apparent that silicon atoms were substituted for aluminum atoms in the Zeolon struc-ture. The framework infrared spectra show shifts to higher wavenumbers following the fluorosilicate treatment. The shift of both the asymmetric stretch band and the symmetric stretch band is characteristic of dealumination accompanied by s~licon substitution in the framework. In the hydroxyl region of the infrared spectrum, the fluorosilicate treated sample shows no increase in absorbance at 3745 cm 1 due to occluted SiOH species. There was a substantial decrease in absorbance at 3710 cm 1 compared to the starting H-Zeolon indicating that there was a decrease in the number of framework vacancies or defect sites.
(C) To gain insight into the silicon substitution mechanism occurring during the treatment procedure in part.(B) above, samples of the H-Zeolon were taken periodically during the course o. treatment and analyzed.
- 6, -1 ~ 71 ~ 37 The results are shown below:
Start of End of After 24 After 4B After 72 ~dditia~ Addieian h~rs of ha~s of hours of of Amnoni- of AmnD- digestion digestion digestion un flwr~ ni~n~ n,.~-sillcate rosilicate X-ray Crystallinity:
(~) by Peak Inten~ity 100 121 107 97 ~6 (b) by Peak Area 100 117 106 99 90 Framew~rk Infrared:
Asymmetric Stretch, cm-l 1073 1~85 1088 1085 1089 Symcetric Stretch cm-l ' 801 813 814 815 815 Hydroxyl Infrared;
~bsolute Abs. at 3710 cm-l 0.325 ~.180 0.160 0.130 0.115 Defect Structure Factor, z 0.137 O.076 O.068 O.055 O.048 From the foregoing, it is apparent that a considerable amount of silicon substitution had taken place by the end of the fluorosilicate addition period.
Example 8 Fluorosilicate Treatment of Mordenite, (a natural ore from Union Pass, Nevada, U.S.A.).
One thousand gm (anhydrous weight) of a ground natural mordenite ore was added to 10 liters of l.ON HCl solution in a 22 liter flask heated at 95C. The slurry was stirred for one hour at 95C, filtered and rinsed with 10 liters of distilled water. The acid exchange procedure was re-peated twice more then the solids were washed with distilled water until the wash water remained clear when tested for the presence of chloride with AgNO3 solution.
(a) Five hundred gm of the H+ mordenite was slurried in 2 liters of distilled water at 75C. A second solution of 1.5 liters of distilled water containing 100.12 gm AFS
was added in a continuous manner to the zeolite slurry at a rate of lO ml./min. The stoichiometric ratio of moles of Si added as AFS to the moles of Al present ~i~
13L71~337 in the zeolite was 0.50. Followin~, the addition of the fluorosilicate solution the slurry was digested for 26 hours under reflux conditions, then fileered and thorou~hly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses of the starting H mordenite and the product of the fluoro-silicate treatment are shown in Table 6A.
S$artin~ T~eated H Mordenite H Mordenite Na20, wt.% 0.29 0.22 (NH4)20, wt.% 1.4j A1203, wt.% 11.46 8.18 SiO2, wt.% 83.56 85.31 F2, wt.% - 2.35 SiO2/A1203 12.37 17.68 Na /Al 0.04 0 04 NH4 /Al _ 0.71 Cation Eguivalent, M /Al 0.48 0.79 A comparison of the properties of the treated zeolite with the starting material is shown in Table 6B.
Starting H+ Treated H+
Mordenite Mordenite .
Chemical SiO2/A1203 12.37 17.68 Chemical M+/Al 0.48 0.79 X-Ray Crystallinity (I) By Peak Intensity 100 89 (II) By Peak Area 100 75 Crystal Collapse Temp.,C(DTA) ~ 1025 No Exotherm Framework Infrared Asymmetric Stretch, cm 1 1085 1098 ~71B37 12346-l TA~LE 6R continued Starting H Treated H
Mordenite Mordenite Symmetric Stretch, cm 1 792 794 Hydroxyl lnfrared Absolute Absorbance at 3710 cm 1 0.225 0.310 The mole fractions of framework tetrahedra (TO2) sre set forth below in Table 6C for the startin~ H~-mordenite and the LZ-211 product.
a) Mole fraction of oxides ~O~; H -Mordenite - (Alo 1~6Sio 779 0 095~
LZ-211 Product- (Al~ 0885io.781 0.131)( b) Mole fraction of aluminum removed; N - 0.038 c) % aluminum removet, N/a x 100 - 30 c) Change in defect structure factor, ~z - 0.036 e) Moles of silicon substitutet per mole of aluminum removet,~N-4z )/N - 0.05 The analytical tata in this case to not conclusively demonstrate that silicon has replaced aluminum in the mordenite framework although the X-ray crystallinity is maintainet. However, because of the particle size of the mordenite crystals unter stuty, it is tifficult to obtain a high degree of infraret transmission throu~h the zeolite wafer. The absorption bants in the framework infraret region are broader and less well definet than for instance with H-Zeolon. Nevertheless, it is obvious that the amount of shift of the asymmetric stretch band is substantially greater than the symmetric stretch bant shift. This is characteristic of a zeolite framework that has been dealu-minated with little or no silicon substitution in the vacant sites. However, the infrared spectrum of the hydroxyl region of the fluorosilicate treated sample did not show 1~71837 anv increased absorbance at 3745 cm 1 due to SiOH species The increase in absorbance at 3?10 cm 1 due to hydrogen bonded OH groups in vacant sites did not increase commen-surate with amount of aluminum removed during the treat-ment.
(b) A second sample of H+-mordenite weighin~ 317 gm (anhydrous wei~ht) was slurried in 2 liters of distilled water at 75C. A se.ond so~ution of 1.5 liters distilled water containing 126.87 ~m (NH4)2SiF6 was added in a con-tinuous manner to the zeolite slurry at a rate of 10 ml per minute. The stoichiometric ratio of moles of Si added as [(NH4)2SiE6] to the moles o' ~1 ~resent in the zeolite was 1.00. Following the addition of the fluoro-silicate solution, the slurry was digested for 48 hours under reflux conditions then filtered and thoroughly washed until te~ts of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses of the starting H+ mordenite and the product of the fluorosilicate treatment are shown in Table 7A, below:
Starting H+Treated H
MordeniteMordenite Na20, wt.% 0.29 0.22 (NH4)20, wt.% _ 1.35 A1203, wt.% 11.46 7.29 SiO2, wt.% 83.56 86.77 F2, wt.% - 3.36 SiO2/A1203 12.37 12.20 Na+/Al 0 04 0.05 NH4 /Al - 0.36 Cation Equivalent, M /Al 0.48 ~0.80 ~17~837 A comparison of the properties of the treated ze~lite with the starting H+ mordenite is shown in Table 7B, below:
Starting H Treated H
Mordenite Mordenite Chemical Si02/A1203 1?.. 37 20.20 Chemical M /Al 0 . 48 0 . 81 X-Ray Crystallinity (I) By Peak Intensity 100 120 (II) By Peak Area 100 102 Crystal Collapse Temp. C(DTA) 1025 .lo Exother~
Framework Infrared Asymmetric Stretch, cm 1085 NA
Symmetric Stretch, cm 1 792 NA
Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.225 0.300 The mole fractions of framework tetrahedra (TO2) are set forth for the starting H+-mordenite and the LZ-211 product in Table 7C below:
a) Mole fraction of Oxides,(TO2) H+-mordenite (Alo 126Sio 779r0 095)0;
LZ-711 (Alo 07~ b.794 0.127)o2 b) Mole fraction of aluminum removed, Ni - 0.047 c) % FraMework aluminum removed, N/a x 100 - 37 t) Change in defect structure factor, ~z - 0.032 e) Moles of silicon substituted per mole of aluminum removed,(N-~ztN) - O.32 As in the case of the preceding Example, proof of silicon substitution rests primarily on chemical analysis and absolute absorbance measurements in the hydroxyl stretching region of the infrared spectrum ( 3710 cm 1).
.
~7:~337 l2346-l The X-ray crystallinity was maintained. The peak area measurement shows the same value as the starting H~-mordenite and the peak intensity measurement indicates an increase in intensity due to peak sharpening. This suggests a more ordered structure than ~he starting H+-mordenite, the exact nature of which is not known at this time. The calculated unit cell ~alues make it quite certain that a substantial amount of silicon has replaced alu~inum in the framework. This alone could be the cause of increased intensity measurements in the X-ray powder pattern. A
sample taken after 24 hours of the fluorosilicate treatment had a SiO2/Al203 ratio of 19.1, a fluoride content of 3.5 wt.~/, and absolute absorbance at 3710 cm l of 0.330. Com-paring this sample to the sample described in Tables 6A, B and C, supra increasing the amount of fluorosilicate in the treatment step increases the amount of silicon substi-tution. Increasing the tigestion time also increased the degree of silicon substitution. It is apparently more difficult to substitute silicon into the framework structure of natural mortenite than it is to substitute it into the framework of synthetic mordenite.
Example 9 Fluorosilicate Treatment of NH4~-L Zeolite to Produce L7-212.
(a) Fifty gm of NaKL zeolite (SiO2/A1203 molar ratio of 6.03) was slurried with 500 ml of 1.0 molar NH4Cl solution at reflux for 16 hours and filtered. The exchange was repeated three times more and the product of the third exchange was washed with hot distilled water until tests of the wash water were negative when tested for chloride with AgNO3 solution From the product lO.0 gm (anhydrous ~7~837 12346-1 weight) was slurried in 100 ml of distilled water heated at 75C. A second solution of 50 ml containing 3.36 gm (NH4)2SiF6 was added to the NH4L-water slurry in 1 ml increments at a rate of 1 ml every five minutes. During the course of the fluorosilicate addition the temperature was maintained at 75C. The stoichiometric ratio of moles of Si added ~s [(~H4` -~iF~, to the mo1es of Al ~resent i~ the zèolite was 0.50. Following addition of the fluorosilicate solution the slurry was heated to 95C for 16 hours, then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions.
The chemical analyses for the starting NH4L and the product of the fluorosilicate treatment are shown in Table 8A, below:
Starting NH4L LZ-212 Product ~2~ wt,% 3.43 2.03 (NH4)20, wt,% 8.35 3.46 A1203, wt,% 19.22 11.15 SiO2,wt,% 68.31 81.38 F2, wt,% - 0,04 SiO2/A1203 6,03 12.39 K+/Al 0.19 0.47 NH4 /A1 0.85 0.61 Cation Equivalent, M /A1 1.04 1.08 A co~parison of the properties of the treated zeolite with the starting material is shown in Table 8B.
117~837 12346-1-C
TAaLE 8B
Bt~rting NH4L LZ-212 Pro~uct Chemic~l SiO2/A1203 6.03 12.3 Chemical M+/Al 1.05 1.0 X-RAy Cryst~llinity (I) By Peak Inte~sity 100 Excellent ~II) By Peak AleaNA NA
Cryst~1 Coll~pse Temp., C (DTA)900 950 Framework In~r~red ~symmetric Stretch, cm 11028 1109 Sy~m~tric Stretch, cm 1 769 782 Hydroxyl Infrared Absolute Ads~rb~nce at 3170 cm 1 0.085 0.1Y5 The frame work mole fractions are set forth in Table 8C
below for the starting NH4L and the LZ-212 product.
TA~LE ~C
a) Mole fraction of oxides ~TO2);
~L - (Alo.o24slo.724 oo.o36)o2 LZ-212 ~Alo, 128Slo. 790 C.082)02 b) Mole fraction of aluminum removed, N: - 0.112 c) Percent of framework aluminum removed, N/a x 100 - 47 d) Change in defect structure factor, ~z - 0.046 e) Moles of silicon substituted per mole of aluminum removed, (N- ~z)/N -0.57 The data show quite conclusively that under the conditions given, silicon substitutes for aluminum in the L
zeolite framework with a high degree of efficiency. X-ray crystallinity is maintained and the thermal stability is apparently increased. More im~ortantly, both the asymmetric stretch ~and and the symmetric stretch band in the framework infrared spectra increase following the treatment. This is a consistent with dealumination , 13~7~837 accompanied by silicon substitution in the framework. ~o absorption was observed at 3745 cm 1 due to occluded SiOH species and there is only a small increas~
in absolute absorbance at 3710 cm 1 which reflects the relative amount of hydrogen bonded OH groups in framework vacancies. Dealumination was nearly stoichiometric with the amount of fluorosilicate added.
(b) In a second experiment a fresh sample of NaY~L was obtained. Three hundred and seventy-two gm of NaKL zeolite (Si02/A1203 molar ratio of 5.93) was slurried with 1000 ml of 6 molar NH4Cl solution at reflux for 16 hours and filtered. The exchange was repeated twice more and the product of the third exchange was washed with hot distilled water until tests of the wash water were negative when testet for chloride with AgNO3 solution.
From the ammonium-exchanged product 10C gh (anhydrous weight) was slurried in 300 ml of distilled water heated at 75C. A second solution of 300 ml containing 33.94 ~m (NH4)2SiF6 was added to the NH4L-water slurry in 10 ml increments at a rate of 10 ml every five minutes.
During the course of the fluorosilicate addition the temperature was maintained at 75C. The stoichiometric ratio of moles of Si added as ['N~L)2';_r~ to the ~.oles of Al present in the zeolite was 0.50. Following addition of the fluorosilicate solution the slurry was maintained at 75C and digested for 24 hours, then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NH4L and the product of the fluorosilicate treatment are shown in Table 9A.
_ 7n _ 12346-l 1~71837 Startin~ NH4L LZ-212 K20, wt.% 3.51 2.66 (NH4)20, wt % 7.89 4.10 A1203, wt.% 19.42 11.52 SiO2, wt.% 67.80 ~9.62 F2, wt.~/o - 0.08 SiO2/Al203 5.92 11.73 K /Al 0.20 0.25 NH4 /Al 0.80 0.70 Cation Equivalent, M /Al1.00 0.95 A comparison of the properties of the treated zeolite with the starting NH4L is shown in Table 9B.
Starting NH4L LZ-212 Chemical SiO2/A1203 5.92 11.73 Chemical M /Al 1.00 0.95 X-2ay Crystallinity (I) By Peak Intensity 100 49 (II) By Peak Area 100 52 Crystal Collapse Tem.,C(DTA) 995 940, Framework Infrared Asymmetric Stretch, cm 1 1028 1108, 1031 Symmetric Stretch, cm 1 768 780 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.048 0.240 The framework mole fractions are set forth below in Table 9C for the starting NH4L and the LZ-212 product.
. . .
1~7~837 12346-1 a) Mole fraction of oxides (T02):
NH4L - (Alo 247Sio.733 0.020)2 LZ-212 - (Alo 13lSio 767 0.102~2 b) Mole fraction of aluminum removed, N; - 0.116 c) Percent of fra~eworK aluminum removed, N/a x lO0 _ 47 d~ Change in defect structure factor,~ z - 0.082 e) Moles of silic~n substituted per mole of aluminum removed, (N-~z)/N _ 0.29 It should be noted that the fluorosilicate digestion temperature in the present example was 75C while that in the previous example was at reflux. The degree of tealumination is the same for both digestion temperatures while the efficiency of silicon substitution is substan-tially retuced at the lower dlgestion temperature.
Example_lO
Fluorosilicate Treatment of Clinoptilolite to Produce LZ-219.
Twenty-five gm. of the natural mineral clinoptilolite (SiO2/A1203 molar ratio of lO.3) was slurried with 200 ml.
of l M. NH4Cl solution at reflux for one hour and filtered.
The exchange was repeated twice more and the product of the third exchange was washed with hot distilled water until tests of the wash water showed negative for chloride.
From the ammonium-exchanged product, 5.~ gm (anhydrous weight) was slurried in lO0 ml of distilled water heated at 95C. A second solution of 50 ml containing 1.17 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml. per 5 minutes. The stochiometrLc ratio of moles of Si added as [ (NH4)2SiF6] to the moles of Al in the zeolite was 0.5. Following the addit.on o' the fluorosilicate solution the slurry was digested for 7~
1~71837 three hours at 95C then thorou~hly washed until tests of the wash water proved ne~ative for both aluminum and flu~rid~
ions. The chemical analyses for the startin~ NH~ Clinopti-lolite and the product of the fluorosilicate treatment ar~
sho~ in Table lOA, below:
TABLE lOA
Starting NH4 Product Clinoptilollte Na20, wt.~/o 0.55 0.66 (NH4)20, wt.% 5.19 3.85 A123' wt.% 12.82 11.33 SiO2, wt.c 77.90 81.41 F2, wt.~/c - 0.53 SiO2/A1203 10.31 12.20 i~a+/Al 0.07 0.10 NH4 /Al 0.79 0.67 Cation Equivalent, M+/Al0.93 0.82 A comparison of the properties of the treated zeolite with the starting material is shown in Table lOB, below:
TABLE lOB
Starting NH Treated NH
Clinoptilol~te ClinoPtilo~ite Chemical SiO2/A1203 10.31 12.20 Chemical I~+/Al 0.93 0.83 X-Ray Crystallinity (I) By Peak Intensity 100 60 (II) By Peak Area 100 60 Crystal Collapse Temp.,C(DTA) 530 533 Framework Infrared Asymmetric Stretch, cm 1 1062 1086 Symmetric Stretch, cm 1 795, 778 796, 778 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.055 0.135 .. . . .
117~B37 The framework mole fractions are set forth in Table lOC
below for the starting NH4-Clinoptilolite and the product.
TABLE lOC
a) ~Iole fraction of oxides (T02); NH4 Clino.- -I
(Alo 159sio.81~~~.023)2 Product (Alo l33Sio.810 0.057)2 b) Mole fraction of aluminum removed, N; - 0.026 c) % of framework aluminum removed; N/a x lO0 - 16 d) Change in defect structure factor, ~z - 0.034 From the data it would appear that rnainly dealumination resulted from the treatment of NH4 Clinoptilolite with the (NH4)2SiF6 at 95C. However the efficiency of dealumination i9 low, indicating that the sites in the framework where the aluminum atoms are located are relatively inaccessible, or that aluminum atoms in the particula~ environment of the clinop~ilolite framework are extremely stable. Accordingly when the experiment is repeated using more rigorous condi-tions, preferred LZ-21~ products within the scope of the preferred co~positions cc tho present invention are formed.
Exam~le 11 Fluorosilicate Treatment of Chabazite to Produce LZ-218 Twenty-five grams of the natural mineral chabazite (SiO2/A1203 molar ratio of 8.5) was slurried with 200 ml of 2 molar NH4Cl solution at-refluY. for one hour and filtered. The exchange was repeated twice more and the product of the third exchange was washed with hot distilled ater until tests of the wash water showed negative for chloride.
1~7~33~7 From the ammonium exchanged prod~ct, 5.0 gm (anhydr~us weight) was slurried in 100 ml of distilled water heated at 95C. A second solution of 50 ml containing 2.60 ~m (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml per five minutes. The stoichiometric ratio of moles of silicon added as l(N~.4)~Si~6] to the moles of aluminum present in the zeolite was 1.00. Following the addition of the fluorosilciate solution the slurry was digested for three hours at 95C then thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for tne starting NH4 chabazite and the product of the fluorosilicat~
treatment are shown in Table llA, below:
TABLE llA
Starting NH4- LZ-218 Chabazite Product Na20, wt.% NA 0.85 (NH4~20, wt.% 4.98 3.30 A1203, wt.% 14.83 12 05 SiO2, wt.% 74.51 78.98 F2, wt.% NA 0.39 SiO2/A1203 8.52 11.13 Na tAl NA 0.12 NH4 /Al 0.66 0.54 Cation Equivalent, M /Al 0.66 0.94 A comparison of the properties of the treated zeolite with the starting material is shown in Table llB, below:
117~837 TABLE llB
Starting NH4 LZ-218 Chabazite Product Chemical SiO2/A1203 8.52 11.13 Chemical M /Al 0.69 0.94 X-Ray Crystallinity (I) By Peak Intensity 100 164 (II) By Peak Area 100 106 Crystal Collapse Temp.,C(DTA) Sinter 940C Exotherm 930C
Framework Infrared Asymmetric Stretch, cm 1 1042 1096 Symmetric Stretch, cm 1 771 785 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.0750.145 The framework mole fractions are set forth in Table llC
below for the starting NH4 chabazite and the LZ-218 products TABLE llC
a~ Mole fraction of framework oxides (T02); NH4 Chabazite -(Alo 184sio.784 0.032)2 (Alo 143Sio.7gs 0.062)2 b) Mole fraction of aluminum removed, N- 0.041 c) % framework aluminum removed; N/a x 100 - 22 t) Change in defect structure factor , ~z, - 0.030 e) Moles of silicon substituted per mole of aluminum removed; (N-4z)/N - 0.27 The data indicate that silicon has replaced aluminum in the chabazite framework. The efficiency of aluminum removal is relatively low compared with the Y, L and mordenite zeolites, and comparable to that observed in the case of clinoptilolite. However with chabazite, silicon does replace the removed aluminum in the framework as shown by the shift 1~7~837 of both the asymmetric stretch band and the symmetric stretch band of the framework infrared spectrum to higher wavenumbers Additionally, no evidence was found to indicate occlusion of amorphous SiOH species which would account for the increased silicon content in the zeolite. The increase in X-ray peak intensity while the peak area remains constant is taken as further evidence of silicon substitution in the framework.
Example 12 Fluorosilicate Treatment of Erionite to Produce LZ-220.
A 5.0 gm (anhydrous weight) sample of an ammonium exchanged natural erionite was slurried in lOOml. of distilled water heated at 95C. A second solution of 50 ml containing 1.60 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml per minute.
The stoichiometric ratio of moles of Si added as ~N~14)~51P6]
to the ~oles of Al present in the zeolite was 0.54.
Following the addition of the fluorosilicate solution the slurry was tigested for three hours at 95C then thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NH4 Erionite and the product of the fluorosilicate treatment are shown in Table 12A, below:
Starting NH4 Product Erionite LZ-220 Na20, wt.% 0.35 0.24 (NH4)20, wt.% 5.75 3.54 A1203, wt.% 16.80 13.24 SiO2, wt.% 68.93 76.26 F2, Wt.% - 0.39 .
1~71837 TABLE 12A ¢ontinued) Starting NH4Product Erionite LZ-~'J
SiO2/A1203 6.96 9.77 Na /Al 0.03 0,03 1 0.67 0.52 Cation Equivalent, M /Al 0.91 0.79 A comparison of the properties of the treated zeolite with the starting material is shown in Table 12B, below:
Starting NH4Product Erionite LZ-220 Chemical SiO2/A1203 6.96 9.77 Chemical M /Al 0.91 0.79 X-Ray Crystallinity (I) By Peak Intensity 100 172 (Il) By Peak Area 100 150 Crystal Collapse Temp.,C(DTA) 976 995 Framework Infrared Asymmetric Stretch, cm 1 1052 1081 Symmetric Stretch, cm 1 781 784 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0 0700.160 The framework mole fractions are set forth in Table 12C
below for the starting NH4-Erionite and the product zeolite.
a) Mole fraction of framework oxides, (T02);
NH4 Erionite - (Alo 217Sio,753 0 030)2 Product LZ-22~ ~Alo 158sio.774 0.068)2 b) Mole fraction of aluminum removed, N - 0.059 c) % of framework aluminum removed, N/a x 100 - 27 .. . . .
1~7~837 d) Change in defect structure factor, ~z - 0.038 e) Moles of silicon substituted per mole of aluminum removed, (N-~z)/N _ 0.36 The data establish the feasibility of substitutin~ silicon for framework aluminum in erionite by the method of the present invention, Vsing the conditions described, however, the efficiency of aluminum removal and of silicon substi-tution are relatively low. Using more rigorous reaction conditions results in the formation of a preferr~d LZ-"20 product within the scope of the novel compositions of the invention.
Example 13 Fluorosilicate Treatment of Offretite to Produce LZ-217.
Approximately 50 grams of synthetic TMA offretite was slowly calcined to 550C and held 24 hours. The calcined offretite (Si02/A1203 molar ratio of 9.2~ was slurried with 300 ml of 1.3 molar NH4 Cl solution at reflux for one hour and filtered. The exchange was repeated twice more and the product of the third exchange was washed with hot distilled water until tests of the wash water showed negative for chloride.
From the ammonium exchanged product, 5.0 ~m (anhydrous weight) was slurried in 100 ml of distilled water heated at 95C. A second solution of 50 ml containing 1.25 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml per five minutes, The stoichiometric ratio of moles of silicon added as [!N.L4)2SiF6] to ~he moles of aluminum present in the zeolite was 0.51. Following the addition of the fluorosilicate solution the slurry was digested for three hours at 95C then thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NH4 Offretite and the product of the fluorosilicate ~ 7~837 12346-1 treatment are shown in Table 13A, bel~w:
TABLE l3A
Startin~ NH - LZ-217 Offretite 4 Product K20, wt.% 2.48 1.47 (NH4)20, wt.% 5.31 2.72 A1203, wt.% 14.05 8.27 SiO2, wt.% 76.15 84.71 F2, wt.% - 0.12 SiO2/A1203 9.20 17.38 ~ /Al 0.19 0.19 NH4 /Al 0.74 0.64 Cation Equivalent, M /Al 0.93 0.84 A comparison of the properties of the treated zeolite with the starting material is shown in Table 13B, below:
Startin~ NH - LZ-217 Offretite 4 Product Chemical SiO2/A1203 9.20 17.38 Chemical M+/Al 0.93 0.84 X-Ray Crystallinity (I) By Peak Intensity 100 59 (lI) By Peak Area 100 60 Crystal Collapse Temp.,C(DTA) 1001 1043 Framework Infraret Asymmetric Stretch, cm 11083 1094 Symmetric Stretch, cm 1789 793 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.140 0.239 The framework mole fractions are set forth in Table 13C
below for the startin~ NH4 offretite and the LZ-217 product.
1~71~37 12346-1 TABLE 13_ a) M~le fraction of framework oxides (TO2); NH4 Offretite -(A1~ 168Sio 773 0.059)2 LZ-217-(Alo 093sio.806 0.101)2 b) Mole fraction of aluminum removed; N - 0.075 c) % framework aluminum removed; N/a x lOO - 45 d) Change in defect structure factor, ~z - 0. 042 e) Moles of silicon substituted per mole of aluminum removed, (N-~z) /N - O . 44 The data show that dealumination and silicon substitution do occur in the erionite framework as a result of the fluorosilicate treatment. Some degradation of the structure seems apparent rro~ the X-ray crvstallinit,v data.
However, oxygen adsorption values for the starting NH4 Offretite and the treated product are nearly identical (16-17 wt.% 2 at 100 Torr and -183C). The efficiency of tealumination under the described conditions is quite high and the efficiency of silicon substitution can be increased with longer digestion times.
Example 14 Fluorosilicate Treatment of Zeolite W.
Eight gm of synthetic zeolite W (Si02/A1203 molar ratio of 3.66) was slurried in 100 ml of 1;1 molar NH4Cl solution at reflux for one hour and filtered. The exchange was repeated twice more, the third and final exchange being carried out over 16 hours. The product was then washed with hot distilled water until tests of the wash water showed neRative for chloride.
From the NH4W product, 5.0 gm (anhydrous weight) was slurried in 100 ml distilled water heated at 95~C.
A second solution of 50 ml containing 2.21 gm (NH4)2SiF6 1~7~33~
wad added to the slurry in 2 ml increments at a rate of 2 ml every five minutes. During the course of the fluoro-silicate addition the slurry temperature was maintained at 95C. The stoichiometric ratio of moles of Si added as [(NH4)2SiF~7 to the moles of Al present in the zeolite was 0.49. Following addition of the fluorosilicate solution, the slurry was digested for three hours at 95C then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions.
The chemical analyses for the starting NH4W and the product of the fluorosilicate treatment are shown in Table 14A, below:
Starting NH4W Trested NH
K20, wt.% 0.81 0.57 (NH4)20, wt.% 11.37 4.19 A1203, wt.~/o 25.99 11.88 SiO2, wt.% 59.40 81.67 F2, wt.% - 0.62 SiO2/A1203 3.88 11.67 K /A1 0.03 0-05 NH4~/Al 0.86 0.69 Cat$on Equivalent, M /Al 0.89 0.79 A comparison of the properties of the treated zeolite with the starting material is shown in Table 14B, below:
_ ~ _ 1~7~&~37 TABLE l~B
Startinq NH4W Treated NH4W
Chemica~ SiO2/A12~3 3.88 11.67 Chemical Ml/Al 0.89 0.79 X-~ay Crystallinity ~) By Peak Intensity 100 ~7 ~ By Peak A*ea 100 3S
Unit Cell ~a~) in A 20.2~6 20.145 Crystal Collapse ~emp., ~C (DTA) 1031 1025 Framework ~nfrared Asymmetric Stretch, cm 1 1020 lOB4 Symmetric Stretch, cm~l 780 ~88 Hydroxyl Infrared Abso'ute Absorbance at 3710 cm 1 o.o75 0.310 The framework mole fractions are set forth in Table 14C
below for the starting NH4W and the product zeolite.
a) Mole fraction of framework oxides (T02);
NH4W - (Alo 32gSio~639 0~032)2 Product(A10 127sio~74l 0.131)2 b) Mole fraction of sluminum removed; N - 0.202 c) % of framework aluminum removed; N/a x lO0 - 61 d) Change in defect structure factor; ~z - 0.099 e) Moles of silicon substituted per mole of alumin~n removed;(N-~z)/N - 0.51 The tata establishes the feasibility of substituting silicon for framework aluminum in zeolite W using the process of the present invention. The X-ray crystallinity tata couplet with some preliminary sdsorption tata, however, inticate that an undue amount of crystal tegradation occurred using the specifiet reaction conditions, with the consequent protuct$on of a zeolite which toes not qualify as preferred LZ-216.
Evidence for silicon substitution is established by the shift of framework infrared absorption bands to higher wavenumbers ~7~837 and the relative size of the broad absorption band in the hydroxyl .egion of the infrared spectrum which does not correlate well with the high level of dealumination.
Chemical analysis data of both the solid and the liquid phases of the reaction showed that silicon was indeed incorporated into the zeolite. With no increased absor-bance at 3745 cm 1 of the infrared spectrum indicative of amorphous SiOH species as additional evidence, it must be concluded that siliccr.was incorporated into the zeolite framework during the treatment.
The cause of the structure degradation is believed to be the extensive dealumination of the framework without adequate silicon substitution. Accordin~ly the reactiD~ shoul~, in order to produce LZ-216, be carried out in the presence of a buffer solution such as ammonium acetate. As a general proposition the higher the aluminum content of the starting zeolite, the greater the need for buffering.
When this is tone, preferred LZ-216 results as the product.
Exam~le 15 Fluorosilicate Treatment of Zeolite Rho.
A sample of NH4Rho zeolite which contained a sparingly soluble chloride salt was extracted for a period of ei~ht days in a Soxhlet extraction apparatus. From the washed NH4 Rho zeolite 25.0 gm (anhydrous weight) was slurried in 200 ml distilled water heated at 75C. A second solution of 100 ml containing 8.5 gm (NH4)2SiF6 was added to the slurry in 3 ml increments at a rate of 3 ml every five minutes. During the course of the fluorosilicate addition the slurry temperature was maintained at 75C. The stoichiometric ratio of moles of Si added as [!~H4)~LF5] to ~7~837 the moles of Al present in the zeolite was 0.50. Following addition of th fluorosilicate solution, the slurry was disqested for 24 hours at 75C then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NHg Rho and the product of the fluoro-silicate treatment are shown in Table 15A, below:
Starting NH4-Rho Treated NH4-Rho Cs20, wt. ~ 3.02 2.07 ~NH4)20, wt t 9.53 4.48 A123' t- ~ 19.30 11.03 SiO2, wt. ~ 6~.33 80.34 F2, wt. t - 0.06 Si2/A1203 5.92 12.36 Cs/Al 0.06 0.07 NH4~/A1 0.81 0.80 Cation Equivalent, Ml/A1 0.ô7 0.86 A compari~on ot the properties of the treated zeolite with tne startlng NH4 Rho is ~hown ln Table 158, below.
TA~LE 150 Starting NH4-Rho Tre~ted NH4-Rno Chemlcal 6iO2/A12035.92 12.36 Chemlcal ~/Al O.ô7 0.86 X-Ray Cryst~llinity ~I~ By Peak Intensity100 70 (II) By Peak Area 100 70 Unit Cell (aO) in A14.99114.927 Cry6tal Collapse Temp., C ~DTA) 975975, 1165 Framework Infrared ~ymmetrlc Stretch, cm 11049 1100, 1055 6ymmetrlc Stretch, cm 1~01 800 NydroKyl Int'r~red Absolute Adsorb~nce at 3710 cm 10.0750.0340 ~71837 12346-1-C
The framework tetrahedral mole, fractions are set forth in Table 15C below for both the starting NH4 ~ho and the product zeolite.
Table 15C
~) MOle fr~cti~n of fr~ework oxides (T02~;
NH4Rh~ - (Alo.245Sl~.7? ~0.~31) ~
Pr~uct- (Alo ll~SIo.73 ~ .144)2 b) Mole fr~cti~n o~ ~luminum re~oved, N: - 0.126 c) Percent of fr~mework aluminum remo~ed, N/a x 100 - 51 d) Change in deect ~tructure factor, ~z - 0.113 e) Moles ~f ~ilicon substituted yer mole of luminu~ rem wed, ~N- ~z)~N - 0.10 From the calculated unit cell compositions it appears that a relatively small amount of silicon was incorporated into the zeolite Rho framework during the treatment. This is consistent with the very large shift of the asymmetric stretch absorption band of the framework infrared region and the lack of shift for the symmetric stretch band. The efficiency of dealumination is high but under the conditions employed, the ef~iciency of silicon substitution is low. A LZ-214 product within the scope o~ the preferred novel compositions of this invention and having the characteristic crystal structure of zeolite Rho is produced by digesting at a higher temperature and employing additional buffering agents to protect the zeolite from acid attack.
Example 16 Preparation of LZ-210.
Ten gm. (anhydrous weight) of ammonium zeolite Y
(SiO2/A1203 molar ratio - 4.93) were slurried in 100 ml of 3.4 molar ammonium acetate solution at 75C. A 50 ml solution of water containing 4.63 gm Li2SiE6 2~20 was ~C
~L3l718~7 added to the zeolite slurry in 1 ml incremenes at an addi-tion rate of 1 ml. every 5 minutes. Followin~ addition o~
the Li2SiF6 solution, the reaction mixture was dip,ested 17 hours at 75C, with stirring. After the di~estion period the reaction mixture was filtered and the filter cake thorou~hly washed with distilled H20 until tests of the wash water proved negative for both fluoride and aluminum ion.s. The product was dried two hours at 110C
in air. The chemical and other analyses for the starting NH4Y zeolite and the LZ-210 product zeolite are set forth below.
NH4YLZ-210 Product Na20-wt.% 2.5 0.6 (NH4)20-wt./o 9.5 3.7 Li20-wt.~/o - 0.4 A123 wt.% 22.2 9.7 SiO2-wt.% 64.4 85.0 SiO2/A1203(molar) 4-93 14.80 Na /Al 0.19 0.10 NH4+1A1 0.84 0.74 Li /Al - 0.13 Cation Equivalent (M /Al) 1.03 0.98 X-Ray Crystallinity:
(I) By Peak Intensity 100 83 Unit Cell Dimension(aO) 24.712 24.393 Framework Infrared:
Asymmetric Stretch, cm-l 1015 1061 Symmetric Stretch, cm 1 787 818 Hydroxyl Infrared:
Absolute Absorbance at 3710 cm 1 _ 0.160 Defect Structure Factor,z0.000 0.068 _ R7 -1~718~7 12346-l The framework mole fractions of tetrahedra are set forth below for ~he startin~ NH4Y and the LZ-210 product.
a) Mole fraction of framewor~ oxides (T02);
NH4Y (Alo 2g9SiO.711 0)~2 LZ-210 (Alo lllSio.821 0.068)2 b) Mole fraction of aluminum removed; N - 0.178 c) % framework aluminum removed; N/a x lO0 - 62 d) Change in defect structure factor; ~z - 0.068 e) Moles of silicon substituted per mole of aluminum removed; (N-~z)/N - O.62 In addition to the above described properties, the crystal collapse temperature of the LZ-210 product as measured by the standard DTA procedure was at 1128C.
The untreated NH4Y crystal collapse temperature measured by the same DTA technique was at 890C.
Example 17 Preparation of LZ-210.
Ten g~. (anhydrous weight) of ar,~or.ium zeolite Y
(SiO2/A1203 ~olar ratio - 4.93) were slurried in 100 ml of 3.4 molar am~onium acetate solution at 75C. Reagent grate K2SiF6 (5.32 gm) crystals were added directly to the slurry. The reaction mixture was digested at 75C
with stirring for two days, after which it was filtered and the filter cake thoroughly washed with hot distilled water until tests of the wash water proved negative for both fluoride and aluminum ions. The X-ray powder pattern obtained on the dried product did not show any extraneous peaks indicative of impurities, precipitated in the zeolite matrix. The chemical and other analyses for the starting NH4Y zeolite and the LZ-210 product zeolite are set forth below.
~71837 12346-~
NH4Y LZ-210 Pr~duct Na20-wt.% 2.5 1.2 (NH4)20-wt. D/~ 9.5 1.6 K20-wt.% _ 5.6 A1203-wt . ~/o 22 . 2 11. 4 SiO2-wt.% 64.4 78.7 SiO2/A1203(molar) 4.93 11.72 Na /Al 0.19 0.18 NH +/Al 0.84 0.27 K /Al ~ 0 53 Cation Equivalent(M /Al) 1.03 0.98 X-Ray Crystallinity:
By Peak Intensity lO0 44 Unit Cell Dimension (aO) 24.712 24.514 Framework Infrared:
Asymmetric Stretch, cm 1 1015 1047 Symmetric Stretch, cm 1 787 799 Hytroxyl Infrared:
Absolute Absorbance at 3710 cm 1 _ 0. 210 Defect Structure Factor, z 0.000 0.089 The framework mole fractions of tetrahedra are set forth below for the starting NH4Y and the LZ-210 product.
a) Mole fraction of framework oxites (T02);
NH4Y - (Alo.289sio.7ll 0) 2 LZ-210 - (Al~ 133Sio.773 0~o89)o2 b) Mole fraction of aluminum removed; N - 0.156 c) V/o framework aluminum removed; N/a x 100 - 54 d) Change in defect structure factor; ~z - 0. 089 e) Moles of silicon substituted per mole of aluminum removed; (N-az)/N - O.43 ~7~37 12346-1 In addition to the above described properties, the crystal collapse temperature of the LZ-210 product as measured by the standard DTA procedure was at 1072C.
The untreated NH4Y crystal collapse temperature measured by the same DTA technique was at 890C.
Example 18 Ten gm. (anhydrous weight) of ammonium zeolite Y
(SiO2/A1203 ratio = 4.93) were slurried in 100 ml of 3.5 molar ammonium acetate solution at 75C. A 50 ml solution of water containing 6.63 gm MgSiF6-6H20 was added to the slurry in increments of 1 ml, at a rate of 1 ml every 5 minutes. Following addition of the MgSiF6 solution the reaction mixture was digested 17 hours at 75C, with stirring. After the digestion period, the reaction mixture was filteret and the filter cake thoroughly washed with tistillet water until tests of the wash water proved negative for both fluoride and aluminum ions. The X-ray powder pattern obtained on the product showed the presence of a substantial amount of (NH4)M~AlF6 in the product. The fluoride containing product was Soxhlet extracte~ w'th wa~e~
for 60 hours with the result that a negligible amount of NH4MgAlF6 was removed from the product. Wet chemical analyses and X-ray powder tiffraction both indicated that the protuct was a mixture of ~5% zeolite and 15% NH4MgAlF6.
The chemical ant other analyses for the starting NH4Y zeolite ant the LZ-210 protuct zeolite are set forth below:
~ 837 12346-1 As Prepared:
NH4Y LZ-210 Product Na20, wt.% 2.5 0.6 (NH4)20, wt.% 9.5 3.2 MgO, wt.% - 6.9 A1203, wt.% 22.2 15.2 SiO2, wt.% 64.4 65.6 SiO2/A1203(molar) 4.93 7.30 F2 ~ Wt . % none 9.2 __ _ _ Corrected for 15 wt./, NH4MgAlF6:
SiO2/A1203 4.93 9.93 Cation Equivalent(M /Al)1.03 1.12 X-ray Crystallinity intensity 100 100 Unit Cell Dimension(aO)24.712 24.454 Framework Infrared:
Asymmetric Stretch, cm 1 1015 1045 Symmetric Stretch, cm 1787 811 Hydroxyl Infrared:
Absolute absorbance @3710cm 1 _ 0 077 Defect Structure Factor, z 0,000 0 033 The framework mole fractions of tetrahedra are set forth below for the starting NH4Y and the LZ-210 product which has been corrected for the presence of 15 wt.% NH4MgAlF6.
a) Mole fraction of framework oxides(T02);
NH4Y - (A10.289SiO 711 0.000 2 LZ-210 - (Alo,l61Sio,806 0.033 2 b) Mole fraction of aluminum removed; N - 0.128 c) % framework aluminum removed; N/a x 100 - 44 d) Change in defect structure factor; ~z - 0.033 e) Moles of silicon substituted per mole of aluminum removed; (N-az)/N _ 0 74 ,., . ql ~7~837 12346-l Exam~le 19 Fluorosilicate Treatment of NH4~-Omega Zeolite to Produce LZ-213.
(a) A 5.0 gm. sample of Na,TMA-Omega, which had been calcined to remove the tetramethylammonlum catlon~ ar.~ t~lDr ~n-exchanged with ammonium cations, was slurried in 100 ml.
distilled water heated to 95~C. A second solution of 50 ml containing 1.48 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml every 5 minutes.
During the course of the fluorosilicate addition, the slurry temperature was maintained at 95C. The stoichiometric ratio of moles of Si added as [(~H4)2SiF6~ to the moles of Al present in the zeolite was 0~55. Following addition of the fluorosilicate solution, the slurry was digested 3 hours at 95C, then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions.
The resulting product was only 30~ crystalline indicating that the described treatment conditions were too rigorous for the omega structure. No further charac-terization was obtained with this sample.
tb) A second sample of ammonium-exchanged-calcined TMA
Omega zeolite, weighing 1.5 gm, was slurried in 200 ml of 3.4 molar ammonium acetate solution and heated to 75C.
A second solution of 50 ml containing 0.36 gm (NH4)2SiF6 in water was added in one ml increments at a rate of one m~ every minute. During the course of the fluorosilicate addition, the slurry temperature was maintained at 75~C.
The stoichiometric ratio of moles of silicon added as [(NH4)2SiF6] to the moles of aluminum present in the zeolite _ 92 -~ ~'73~83,7 was 0.5. Followin~ addition of the fluorosilicate, th~
slurry was digested for 3 hours at 75~C, then filter~d and thoroughly washed until tests of the wash water proved negative for both aluminum an~ fltloride lons.
The chemical analyses for the starLin~ ~H4-Omega and th~
product of the fluorosilicate treatment are shown in Table 16A, below:
Starting NH4+-Omega LZ-213 Product ~a20, wt.-~ -- 0.16 (NH4)20, wt.-% 8.26 7.93 A1203, wt.-~ 19.56 18.35 SiO2, wt.-% 71.48 72.30 F2, wt.-Z -- 0.18 SiO2/A1203(molar) 6.20 6.67 Na+/Al -- 0.01 NH4 /Al 0.83 0.85 Cation Equivalent, M+/Al0.83 0.86 The comparison of the properties of the treated zeolite with the starting material is shown in Table 16B, below:
Starting NH4+-Omega LZ-213 Product X-Ray Crystallinity (I/Io) 100 109 Framework Infrared Asymmetric stretch, cmIl 1040 1045 Symmetric stretch, cm 810 812 Hydroxyl Infrared Absolute Absorbance at 3710 cm-l 0.039 0.061 Defect Structure Factor, z 0.017 0.026 _ 9~ _ ~'7~ ~ 37 The framework mole fractions are set forth below for the starting NH4 -Omega and the LZ-213 product.
a) Mole Fraction of-Oxides(To2) NH4 -Omega (Alo 239Sio.744 0.017) 2 (Alo 225Sio.749 0.026)o2 b) Mole fraction of aluminum removed, N - 0.014 c) Percent of framework alumimlm r~moved, (~/a) x 100 - 6 d) Change in Defect Structure Factor, ~z - 0.009 e) Moles of silicon substituted per mole of aluminum removed, (~-~z)/N - 0.36 This example is Sllustrative of a zeolite sample that has been both treated too harshly (high temperature and pH, concentrations) causing excessive crystal degradation,and too mildly such that the dealu~.ination was too slow and silicon substitution could not occur to a substantial level even though the efficiency of silicon substitution was nearly 40%.
The novel zeolite compositions of the present invention are useful in all adsorption, ion-exchange and catalytic processes in which their less siliceous precursors have heretofore been suitably employed. In general, because they are more highly siliceous than their precursors they are not only more thermally and hydrothermally stable than those prior known materials but also have increased resistance to~;ard acidic agents such as mineral and organic acids, S02, S03,~Cx and the like. These new zeolites are thus highly useful as selective adsorbents for these materials from, for example, gas streams containing same in contact sulfuric acid plants. Also since their crystal structures are notably 1~ in defect structure and the g ~
~7~1837 zeolitic cations are ion-exchangeahle for other cation species, both metallic and non-metallic, these zeolite compositions are readily tailored by known methods to suit the requirements of a broad spectrum of catalyst com?osi-tions, particularly hydrocarbon conversion catalysts.
The non-metallic cation sites can also be thermally deca-tionized in the known manner to produce the highly acidic zeolite forms favored in most hydrocarbon conversion reactions.
The novel zeolites of this invention can be compounded into a porous inorganic matrix such as silica-alumina, silica-magnesia, silica-zirconia, silica-aluminia-thoria, silica-alumina-magnesia and the like. The relative propor-tions of finely divided zeolite and inorganic matrix can vary widely with the zeolite content ranging from about 1 to 90 percent by weight, preferably from about 2 to about 50 percent by weight.
Amo~g the hydrocarbon conversion reactions catalyzed by these new compositions are cracking, hydrocracking, alkylation of both the aromatic and isoparaffin types, isomerization including xylene isomerization, polymerization, reforming, hydrogenation, dehydrogenation, transalkylation and dealkylation, and catalytic dewaxing.
Using these zeolite catalyst compositions which contain a hydrogenation promoter such as platinum or palladium, heavy petroleum residual stocks, cyclic stocks and other hydrocrackable charge stocks can be hydrocracked at temperatures in the range of 400F to 825F using molar ratios of hydrogen to hydrocarbon in the range of between 2 and 80, pressures between 10 and 3500 p.s.i.g., and a liquid hourly space velocity (LHSV) of from 0.1 to 20, preferably 1.0 to 10.
oc _ 1~7~837 The catalyst compositions employed in hydrocrackin~
are also suitable for use in reforming processes in which the hydrocarbon feedstocks contact the catalyst at tempera-tures of from about 700F to 1000F, hydrogen pressures of from 100 to 500 p.s.i.g., LHSV values in the ran~e of 0.1 to 10 and hydrogen to hydrocarbon molar ratios in the range of 1 to 20, preferably between 4 and 12.
These same catalysts, i.e. those containing hydro-genation promoters, are also useful in hydroisomerization processes in which feedstocks such as normal paraffins are converted to saturated branched chain isomers. Hydroiso-merization is carried out at a temperature of from about 200F to 600F, preferably 300F to 550F with an LHSV
value of from about 0.2 to 1Ø Hydrogen is supplied to the reactor in ad~.ixture with the hydrocarbon feedstoc~
in molar proportions (H/Hc) of between 1 and 5.
At somewhat hi~her temperatures, i.e. from about 650F
to 1000F, preferably 850F to 950F and usually at some-what lower pressures within the range of about 15 to 50 p,s,i.g,, the same catalyst compositions are used to hdyro-isomerize normal paraffins, Preferably the paraffin feed-stock comprises normal paraffins having a carbon number range of C7-C20, Contact time between the feedstock and the catalyst is generally relatively short to avoid unde-sireable side reactions such as olefin polymerization and paraffin cracking, ~HSV values in the range of 0,1 to 10, preferably 1,0 to 6,0 are suitable.
The $ncrease in the molar SiO2/Al203 ratios of the present zeolite compositions favor their use as catalysts in the conversion of alkylaromatic compounds, particularly the catalytic disproportionation of toluene, ethylene, 7~337 trimethyl benzenes, tetramethylbenæenes and the like. In the disporportionation process isomerization and trans-alkylation can also occur. Advantageously the catalyst form employed contains less than 1.0 weight percent sodi~m as Na20 and is principally in the so-called hydrogen cation or decationized form. Group VIII noble metal adjuvents alone or in conjunction with Group VI-B metals such as tungstem, molybdenum and chromium are preferably included in the catalyst composition in amounts of from about 3 to 15 weight-% of the overall composition. Extraneous hydro-gen can, but need not be present in the reaction zone which is maintained at a temperature of from about 400 to 750F, pressures in the range of 100 to 2000 p.s.i.g. and LHSV values in the range of 0.1 to 15.
Catalytic cracking processes are preferablv carried out using those zeolites of this invention which have SiO2/
A1203 molar ratios of 8 to 12, less than 1.0 weight-%
Na20 and feedstocks such as gas oils, heavy naphthas, deasphalted crude oil residua etc. with gasoline being the principal desired product. The decationized form of the zeolite and/or polyvalent metal cationic form are advantageously employed. Temperature conditions of 850 to 1100F, LHSV values of 0.5 to 10 and pressure conditions of from about 0 to 50 p.s.i.g. are suitable.
Dehydrocyclization reactions employing paraffinic hydrocarbon feedstocks, preferably normal paraffins having more than 6 carbon atoms, to form benzene, xylenes, toluene and the like are carried out using essentially the same reaction conditions as for catalytic cracking. The preferred form of the zeolite employed as the catalyst is ~ 7~37 12346-l that in which the cations are principally metals of ~,roup II-A and/or II-B such as calcium, strontium, ma~nesium.
Group VIII non-noble metal cation can also be employed such as cobalt and nickel.
In catalytic dealkylation wherein it is desired to cleave paraffinic side chains from aromatic nuclei without substantially hydrogenating the ring structure, relatively high temperatures in the range of about 800-1000F are employed at moderate hydrogen pressures of about 300-lO00 p.s.i.g , other conditions being similar to those described above for catalytic hydrocracking. Preferred catalysts are of the relatively non-acidic type described above in connection with catalytic dehydrocyclization. Particularly desirable dealkylation reactions contemplated herein include the conversionof methylnaphthalene to naphthalene and toluene and/or xylenes to benzene.
In catalytic hydrofining, the primary ob;ective is to promote the selective hydrodecomposition of organic sulfur and/or nitrogen compounds in the feed, without substantially affecting hydrocarbon molecules therein. For this purpose it is preferred to employ the same general conditions described above for catalytic hydrocracking, and catalysts of the same ~eneral nature described in connection with dehydrocyclization operations. Feedstocks include gasoline fractions, kerosenes, jet fuel fractions, diesel fractions, light and heavy gas oils, deasphalted crude oil residua and the like any of which may contain up to about 5 weight-percent of sulfur and up to about 3 weight-percent of nitrogen.
Similar conditions can be employed to effect hydro-fining, i.e., denitrogenation and desulfuriæation, of ~ 3 ~ 12346-1 hvdrocarbon feeds containing substantial proportions of organonitrogen and organosulfur compounds. As observed by D.A. Young in ~.S.P. 3,783,123, it is generally recog-nized that the presence of substantial amounts of such constituents markedly inhibits the activity of catalysts for hydrocracking. Consequently, it is necessary to operat~
at more extreme conditions when it is desired to obtain the same degree of hydrocracking conversion per pass on a relatively nitrogenous feed than are required with a feed containing less organonitrogen compou~.ds. Conseque..~
the conditions under which denitrogenation, desulfuriza~ion and/or hydrocracking can be most expeditiously accomplished in any given situation are necessarily determined in view of the characteristics of the feedstocks in particular the concentration of organonitrogen compounds in the feed-stock. As a result of the effect of organonitrogen compounds on the hytrocracking activity of these compositions it is not at all unlikely that the conditions most suitable for denitrogenation of a given feedstock having a relatively high organonitrogen content with minimal hydrocracking, e.g., less than 20 volume percent of fresh feed per pass, might be the same as those preferred for hydrocracking another feedstock having a lower concentration of hydro-cracking inhibiting constituents e.g., organonitrogen compounds. Consequently, it has become the practice in this art to establish the conditions under which a certain feed i8 to be contacted on the basis of preliminary screen-ing tests with the specific catalyst and feedstocks.
Isomerization reactions are carried out under conditions similar to those described above for reforming, using some-what more acidic catalysts. Olefins are preferably _ 99 _ ~ 7~337 l2346 l isomerized at temperatures of 500-900F, while paraffins, naphthenes and alkyl aromatics are isomerized at tempera-tures of 700-1000F. Particularly desirable isomerization reactions contemplated herein include the conversion of n-heptane and/or n-octane to isoheptanes, iso-octanes, butane to iso-butane, methylcyclopentane to cyclohexane, meta-xylene and/or ortho-xylene to paraxylene, l-butene to 2-butene and/or isobutene, n-hexene to isohexene, cyclo-hexene to methyl-cyclopentene etc. The preferred cation form of the zeolite catalyst is that in which the ion-exchange capacity is about 50-60 percent occupied by polyvalent metals such as Group II-A, Group II-B and rare earth metals, and 5 to 30 percent of the cation sites are either decationized or occupied by hydrogen cations.
For alkylation and dealkylation processes the polyvalent metal cation form of the zeolite catalyst is preferred with less than 10 equivalent percent of the cations being alkali metal. When employed for dealkylation of alkyl aromatics, the temperature is usually at least 350F and ranges up to a temperature at which substantial cracking of the feedstock or con~ersion products occurs, generally up to about 700F, The temperature is preferably at least 450F and not greater than the critical tempera-ture of the compound undergoing dealkylation. Pressure contitions are applied to retain at least the aromatic feed in the liquid state. For alkylation the temperature can be as low as 250F but is preferably at least 350F. In alkylating benzene, toluene and xylene, the preferred alkylating agents are olefins such as ethylene and propy-lene.
- lOo -~ 71 ~ 3 ~ 12346-1 The hydrothermal stability of many of the zeolite compositions of this invention can be enhanced by ccnven-tional steaming procedures. In general the ammonium or hydrogen cation forms of the zeolite are contacted with steam at a water vapor pressure of at least about 0.1 psla, preferably at least 0.2 psia up to several atmospheres.
Preferably steam at one atmosphere is employed. The steaming temperatures range from 100C up to the crystal destruc-tion temperature of the zeolite, but are preferably in the range of 600C to 850C. Steaming periods of a few minutes, e.g. 10 minutes, up to several hours can be employed depend-ing upon the specific temperature conditions. The steaming also produces changes in the selectivity of the catalyst in many cases.
In the above-described catalytic conversion processes the preferred zeolite catalysts are those in which the zeolite constituent has pores of sufficient dlameter to adsorb benzene. Such zeolites include LZ-210, LZ-211, LZ-212, LZ-217 and LZ-213 Example 20 In order to evaluate the catalytic activity of LZ-210 in the catalytic cracking of a gas oil feedstock, a sample of the catalyst was prepared as follows: 990 g. (NH4)2SiF6 were dissolved with stirring $nto 3.8 liters of distilled water at 50C. The solution was put into a dropping funnel fitted on a three-necked round-bottom flask, A solution of 1500 grams of ammonium acetate in 10 liters of water was then added to the flask. Ammonium zeolite Y in the amount of 2500 grams (anhydrous weight, molar SiO2/A1203 =
4.87) was slurried up in the ammonium acetate solution at 75C. A mechanical stirred was fitted to the center hole 337 l2346-l of the flask, which was als~ fitted with the necessary thermo-couples and temperature controllers. Addition of the 3.~ liters of (NH4)2SiF6 solution in lO0 ml. incre-ments begun with a 5-minute interval between each sddition.
The initiàl pH of the slurry was measured at 5.74 and after all of the (NH4)2SiF6 solution was added to the pH
of the slurry was 5.38. The mixture was heated at 95C
with stirring for an additional 18 hours, the dropping funnel ha~ing been replaced with a condenser. The stoichio-metry of the reaction was of the order of one Si added as (NH4)2SiF6 for every two Al atoms present in the zeoli~e.
At the conclusion of the reaction the pH of the slurry was 5.62. The reaction mixture was then filtered and the solids washed with about 25 liters of hot tistilled water, until quantitative tests indicated absence of NH3 and aluminum in the effluent wash water. It was then dried 2 hours at 110C.
The product had a unit cell dimension (aO) of 24.41 A, a cation equivalence of 0,94, and the following compositional mole ratios:
Na20/A1203 e 0~ 076 (NH4)20/A1203 e 0, 862 SiO2/A1203 - 9. 87 The powdered LZ-210 was admixed with 1.5 times its weight of alumina and formed by means of extrusion into 1/16"
pellets. The pellets were calcined at 500C for 6 hours.
The resulting extrudates were sized to 60-lO0 mesh and evaluated for cracking actiivty using a gas oil feedstock, (Amoco FHC-893), in accordance with the procedure of AS~I
test No. D 032,04. The following results were obtained:
~t7~7 12346-1 AST~ Conversion 86.0 G l 35.0 Gasoline2 28.5 Coke3 8.89 H2 0.14 Cl 0.38 C2 + C2 = 1.3 C3 2.6 i-C4 6.5 n-c4 3.2 c4 = 10.8 C5 5.1 (1) weight % feed converted to gas ~2~ Gasoline - wt. product (180F-421F)/Total product (3) Weight % feed converted to coke (gravimetric) ExamPle21 A sample of LZ-210 having a SiO2/A1203 molar ratio of 9.6 and containing 0,7 weight % Na20 was loaded with 0.53 weight percent palladium and composited with sufficient alumina to form an 80% Pd/LZ-210 - 20% A1203 catalyst composition having an average bulk density of 0.48 cc./g.
This catalyst composition was tested for gasoline hydro-cracking performance using the following test conditions:
Feedstock - Gas Oil, API - 39.0, BP.R = 316-789F.
Pressure - 1450 psig.
H2/Oil c 8000 SCF/BBL.
To determine the second stage hydrogenation activity of the catalyst, the feed was doped with 5000 p?m sulfur as throphene. The activity in this regard was, in terms of the temperature required to obtain a 49.0 API product after 100 hours in stream, 498F. To determine the first stage (cracking) activity, the feed was doped with 5000 ppm sulfur as thiophene and 2000 ppm nitrogen as 5-butyla~ine.
The activity in this regard, in terms of the temperature required to obtain a 47.0 API product after 100 hours on stream, was 692F.
_ 1 nL _
The stoichiometric ratio of moles of silicon added to the moles of aluminum present in the zeolite was 0.50. Follow-ing the adtition of the fluorosilicate solution, the slurry was digested for 16 hours at 95C, filtered, and washed with distilled water until tests of the wash water were negative for both aluminum and fluoride ions. The chemical and other analyses for the starting NH4-X zeolite and the product zeolite are set forth below:
1~7~837 NH4-X Product Na20 - wt.~/o 3.2 0.5 (NH4)20 ~ wt.% 10.8 6.5 l2o3 wt.% 34.2 l9.t) SiO2 - wt.% 50.8 72.0 SiO2/A1203 (molar) 2.52 6 . ~3 Na /Al 0.15 0.04 NH +/Al 0. 62 0 . 67 Cation Equivalent (M /Al) 0.77 0.71 X-ray Crystallinity;
(a) by Peak Intensity 100 clO
Unit cell dimension (aO),A.24.945 __ Framework Infrared:
(a) Asymmetric Stretch, cm l 987 1049 (b) Symmetric Srretch, cm 1 749 780 Hydroxyl Infrared;
Absolute Abs. at 3710 cm l0.110 U.224 Defect Structure Factor, z 0.047 0.095 It is apparent from the foregoing data that although dealumination in conjunction with silicon substitution into the zeolite framework did occur, the procedure was highly destructive of the crystallinity of the product zeolite. Also the remaining crystal structure contained an undue number of defect site.
(C) In a second attempt to treat the NH4-X of part (B), a 5 gram sample of the zeolite was slurried in 100 ml. of a 3.4 molar ammonium acetate solution at 95C.
Fifty milliliters of a second aqueous solution containing 1.49 grams of ammonium fluorosilicate was added to the slurry in 2 ml. incremen~s at a rate of 2 ml. every five minutes. The stoichiometric ratio of moles of silicon 12346-l added to the moles of zeolitic aluminum was 0.25. Follo~-ing the completion ofthe addition of the fluorosilicate solution, the slurry was digested for 3 hours, filtered and washed. Although the treatment of this part (C) was much less rigorous than that of part (B) above by v~reue of increased buffering, lower fluorosilicate concentration and shorter digestion time, the product of part (C) was found to be nearly amorphous.
Example 6 ~ he process for substituting extraneous silicon for framework aluminum atoms in a zeolite having the zeoli~e A-type structure is illustrated by the following experi-mental procedure: Approximately S grams of zeolite N-A
(prepared hydrothermally using a combination of sodium hydroxide and tetramethylammonium hydroxide in accordance with the teachings of U.S.P. 3,305,922) having a SiO2/
A1203 molar ratio of 6.0 was calcined in air at 550C
for 17 hours to remove the tetramethylammonlum cations.
The resulting decationized form of the zeolite was ion-exchanged with an aqueous solution of NH4Cl. A twelve gram (anhyd.) sample of the resulting NH4-A zeolite was slurried ~n 300 ml. of an aqueous 3.4 molar ammonium acetate solution at 75C and 100 ml. of an aqueous solution containing 4.63 gm. ammonium fluorosilicate was added thereto in 1 ml. increments at the rate of l ml. per minute. Following completionof the addition of the fluoro-silicate solution, the slurry was digested for 16 hours at 75C filtered, and the solids then tho,oughly washed with water. The preliminary decationization and 1~ 7~837 subsequent rehydration of the starting zeolite introduced a considerable number of defect sites into the zeolite starting material which were not, under the conditions employed in the fluorosilicate treatment, filled by silicon insertion. The observed decrease in the unit cell dimension, aO, from 11.994 to 11.970, however, establishes that extraneous silicon from the fluorosilicate was substituted for original framework aluminum atoms in the zeolite. The results of chemical and other analyses for the starting NH4-NA and the LZ-215 product zeolite are set forth below:
NH4-NA LZ-215 Product Si02/A1203 (molar) 5-43 7.38 Cation Equivalent, (M /Al) 0.65 0.69 X-Ray Crystallinity: .
(a) % by Peak Intensity 100 60 (b) % by Peak Area 100 59 Unit Cell Dimension (aO) 11.994 11.970 Framework Infrared:
asymmetric Stretch, cm 1 1062 1069 symmetric Stretch, cm 1 713 722 Hydroxyl Infrared:
Defect Structure Factor (z)0.042 0.079 Absolute Absorbance at 3710 cm~l 0.100 0.186 The framework mole fractions of tetrahedra are set forth below for the starting NH4-NA and the LZ-215 product.
a) Mole fraction of oxides (T02) - (Alo 2S8Sio 700r~o 042)2 (Alo 196sio.725 0.079)2 b) Mole fraction of aluminum removed,N - 0.062 c) % aluminum removed, N/a x 100 - 24 d) Change in defect structure factor , ~z,- 0.037 e) Moles of silicon substituted per mole of aluminum removed, (~-~z)/N _ 0.40 ~171837 In order to prepare a high silica zeolite of the type-A structure which is substantially free of defect sites it is necessary either to maintain the organic cations in the starting zeolite or to thermally degrade the organic cations to NH4+ or H+ cations under controlled conditions such as minimal decomposition temperatures and in an environment of nitrogen and/or ammonia.
Example 7 (A) The substitution of extraneous silicon into the crystal lattice of a zeolite of the mordenite type is illustrated by this example in which a commercially avail-able synthetic acid-treated mordenite was used as the starting material. One thousand grams of the synthetic mordenite (SiO2/A1203 = 11.67) were slurried in 8 liters of distilled water at reflux temperature. Three liters of an aqueous solution containlng 435 grams of ammonium fluorosilicate was added rapidly to the zeolite-water slurry and the resultant mixture refluxed with stirring for 96 hours. The zeolite product was then isolated by filtration and washed with distilled water. The chemical and other analyses results are set forth below for the starting material and the product zeolite.
B
12346-l 1~7~837 H-Zeolon LZ-211 _ Product Na20, wt.-% 0.48 0.32 (NH4)20, wt.-% __ 1.65 A1203, wt.-% 12.44 6.48 SiO2, wt.-% 85.51 91.88 SiO2/Al203(molar) 11.6' 24.08 Na /Al 0.05 0.08 N~4 /Al __ 0 50 Cation Equivalent, M /Al 0.06 0.58 X ray Crystallinity by Peak Intensity 100 85 Fra~ework Infrared:
Asymmetric Stretch, cmll 1070 1093 Symmetric Stretch, cm 801 811 Hydroxyl Infrared:
Absolute Abs. at 3710 cm 0.185 0.245 Defect Structure Factor, z 0.078 0.104 Since the starting H-2eolon contained a substantial number of defect sites, it is not necessary that the process substitute silicon into those tefect sites. The fact that the process of this invention does not create any substan-tial amount of new defects in the structure is substantiated by the fact that the Defect Structure Factor, "z", increased by only 0.026 as a result of the treatment.
The framework mole fractions of tetrahedra are shown below for the starting H-Zeolon and the LZ-211 Product.
a) Mole fraction of oxides ~TO2) H-Zeolon - (Alo.l34si0.787r0.078 2 LZ-211 - (Alo 069Sio,827 0~lo4~o2 b) Mole fraction of aluminum removed, N - 0.065 c) % Aluminum Removed, N/a x 100 - 49 12346-l 13L7~L~337 d) Change in Defect Structure Factor,~z - 0.026 e) Moles of silicon substituted per mole of aluminum removed, N-~z - 0.60 N
These data show quite conclusively that aluminum has been removed from the structure and replaced with ~ilicon as a result of the fluorosilicate treatment. It is also apparent that the treatment conditions, particularly the rapid addition of the fluorosilicate solution to the zeolite, did not permit the insertion of silicon into all of the sites from which aluminum was removed during the treatment or into all of the aluminum depleted sites of the original H-Zeolon starting material. On the other hand, X-ray crystallinity was maintained, and while no exotherm due to crystal collapse was observed in either sample in differen-tial thermal analyses, sintering began at about 1000C in the starting zeolite but did not occur ùntil about 1150C
in the product zeolite. The framework infrared spectra show shifts to higher wavenumbers following fluorosilicate treatment. The shift of both the asymmetric stretch band and the symmet~ic stretch band is characteristic of dealumina-tion accompan$ed by silicon substitution in the framework.
In the hydroxyl region of the infrared spectrum of the fluorosilicate treated zeolite there was no increase in the 3745 cm 1 band tue to occluded amorphous Si~H. There was only a small increase in absorbance at 3710 cm 1 compared to the starting H-Zeolon indicating that there was only a small increase in the number of framework vacancies due to the treatment. It is to be noted, however, that moderating the severity of the treatment as illustrated in part (B) of the Example, below, results not only in the substantial replacement of aluminum atoms removed during the treatment, but also considerable filling of aluminum-vacant sites in . . .
.
~7~.~337 12346 l the starting zeolite.
(B) In another example, 2500 grams of a similar H-Zeolon starting materi~l as employed in part (A) was stirred in 5 liters of distilled water at 95C. A second solution of 5 liters of distilled water containing 3B2.7 grams of ammonium fluorosilicate at a temperature of about 75C was added directiy to the zeolite-water slurry at a rate of about 50-100 ml. per minute. During the addition period the temperature was maintained at 95C. The stoi-chiometric ratio of moles of silicon added to the moles of aluminum present in the zeolite was 0.41. Follow comple-tion of the addition ofthe fluorosilicate solution, the slurry was digested for 72 hours under reflux conditions, the solids recovered by filtration, and washed with distilled water. The chemical and other analyses results are set iorth below: LZ-211 H-Zeolon _ Prod~ct Na20, wt.-% 0.2 0.2 (L~H4)20, wt,-% __ 2.1 A1203, wt.-% 10.8 5.7 SiO2, wt.-% 88.8 9~.4 S~02/A1203 (molar~ 14.00 24.12 ~a /Al .0 03 0,04 ~H4 /Al -- 0.72 Cation Eauivalent, M /Al 0.03 .~0.76 X-ray Crystallinity:
ta) by Peak Intensity 100 86 (b) by Peak Area 100 90 Fra~ework Infrared:
Asymmetric Stretch, cm 1 1073 1089 Symmetric Stretch, cm 1 801 815 Hydroxyl Infraret:
Absolute Abs. at 3710 cm 1 0.325 0.115 Defect Structure Factor, z 0.137 0.048 1~71837 In this example, the defect structure factor of the starting H-Zeolon is quite large. As a resul~ of the treatment it would appear that a substantial number of the ori~inal defect sites have been eliminated. The framework mole fractions are set forth below for the start-ing H-Ze~lon and the LZ-211 product a) Mole fraction of oxides(TO~ H-Zeolon (Alo 108Sio 755r-0 137) LZ-211 (Alo 073SiO.879 0.048) b) Mole fraction of aluminum removed,~l - o.n35 c) % Aluminum tepletion, N/a x 100 - 32 c) Change in defect structure,~ z - -O.089 From the data it is apparent that silicon atoms were substituted for aluminum atoms in the Zeolon struc-ture. The framework infrared spectra show shifts to higher wavenumbers following the fluorosilicate treatment. The shift of both the asymmetric stretch band and the symmetric stretch band is characteristic of dealumination accompanied by s~licon substitution in the framework. In the hydroxyl region of the infrared spectrum, the fluorosilicate treated sample shows no increase in absorbance at 3745 cm 1 due to occluted SiOH species. There was a substantial decrease in absorbance at 3710 cm 1 compared to the starting H-Zeolon indicating that there was a decrease in the number of framework vacancies or defect sites.
(C) To gain insight into the silicon substitution mechanism occurring during the treatment procedure in part.(B) above, samples of the H-Zeolon were taken periodically during the course o. treatment and analyzed.
- 6, -1 ~ 71 ~ 37 The results are shown below:
Start of End of After 24 After 4B After 72 ~dditia~ Addieian h~rs of ha~s of hours of of Amnoni- of AmnD- digestion digestion digestion un flwr~ ni~n~ n,.~-sillcate rosilicate X-ray Crystallinity:
(~) by Peak Inten~ity 100 121 107 97 ~6 (b) by Peak Area 100 117 106 99 90 Framew~rk Infrared:
Asymmetric Stretch, cm-l 1073 1~85 1088 1085 1089 Symcetric Stretch cm-l ' 801 813 814 815 815 Hydroxyl Infrared;
~bsolute Abs. at 3710 cm-l 0.325 ~.180 0.160 0.130 0.115 Defect Structure Factor, z 0.137 O.076 O.068 O.055 O.048 From the foregoing, it is apparent that a considerable amount of silicon substitution had taken place by the end of the fluorosilicate addition period.
Example 8 Fluorosilicate Treatment of Mordenite, (a natural ore from Union Pass, Nevada, U.S.A.).
One thousand gm (anhydrous weight) of a ground natural mordenite ore was added to 10 liters of l.ON HCl solution in a 22 liter flask heated at 95C. The slurry was stirred for one hour at 95C, filtered and rinsed with 10 liters of distilled water. The acid exchange procedure was re-peated twice more then the solids were washed with distilled water until the wash water remained clear when tested for the presence of chloride with AgNO3 solution.
(a) Five hundred gm of the H+ mordenite was slurried in 2 liters of distilled water at 75C. A second solution of 1.5 liters of distilled water containing 100.12 gm AFS
was added in a continuous manner to the zeolite slurry at a rate of lO ml./min. The stoichiometric ratio of moles of Si added as AFS to the moles of Al present ~i~
13L71~337 in the zeolite was 0.50. Followin~, the addition of the fluorosilicate solution the slurry was digested for 26 hours under reflux conditions, then fileered and thorou~hly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses of the starting H mordenite and the product of the fluoro-silicate treatment are shown in Table 6A.
S$artin~ T~eated H Mordenite H Mordenite Na20, wt.% 0.29 0.22 (NH4)20, wt.% 1.4j A1203, wt.% 11.46 8.18 SiO2, wt.% 83.56 85.31 F2, wt.% - 2.35 SiO2/A1203 12.37 17.68 Na /Al 0.04 0 04 NH4 /Al _ 0.71 Cation Eguivalent, M /Al 0.48 0.79 A comparison of the properties of the treated zeolite with the starting material is shown in Table 6B.
Starting H+ Treated H+
Mordenite Mordenite .
Chemical SiO2/A1203 12.37 17.68 Chemical M+/Al 0.48 0.79 X-Ray Crystallinity (I) By Peak Intensity 100 89 (II) By Peak Area 100 75 Crystal Collapse Temp.,C(DTA) ~ 1025 No Exotherm Framework Infrared Asymmetric Stretch, cm 1 1085 1098 ~71B37 12346-l TA~LE 6R continued Starting H Treated H
Mordenite Mordenite Symmetric Stretch, cm 1 792 794 Hydroxyl lnfrared Absolute Absorbance at 3710 cm 1 0.225 0.310 The mole fractions of framework tetrahedra (TO2) sre set forth below in Table 6C for the startin~ H~-mordenite and the LZ-211 product.
a) Mole fraction of oxides ~O~; H -Mordenite - (Alo 1~6Sio 779 0 095~
LZ-211 Product- (Al~ 0885io.781 0.131)( b) Mole fraction of aluminum removed; N - 0.038 c) % aluminum removet, N/a x 100 - 30 c) Change in defect structure factor, ~z - 0.036 e) Moles of silicon substitutet per mole of aluminum removet,~N-4z )/N - 0.05 The analytical tata in this case to not conclusively demonstrate that silicon has replaced aluminum in the mordenite framework although the X-ray crystallinity is maintainet. However, because of the particle size of the mordenite crystals unter stuty, it is tifficult to obtain a high degree of infraret transmission throu~h the zeolite wafer. The absorption bants in the framework infraret region are broader and less well definet than for instance with H-Zeolon. Nevertheless, it is obvious that the amount of shift of the asymmetric stretch band is substantially greater than the symmetric stretch bant shift. This is characteristic of a zeolite framework that has been dealu-minated with little or no silicon substitution in the vacant sites. However, the infrared spectrum of the hydroxyl region of the fluorosilicate treated sample did not show 1~71837 anv increased absorbance at 3745 cm 1 due to SiOH species The increase in absorbance at 3?10 cm 1 due to hydrogen bonded OH groups in vacant sites did not increase commen-surate with amount of aluminum removed during the treat-ment.
(b) A second sample of H+-mordenite weighin~ 317 gm (anhydrous wei~ht) was slurried in 2 liters of distilled water at 75C. A se.ond so~ution of 1.5 liters distilled water containing 126.87 ~m (NH4)2SiF6 was added in a con-tinuous manner to the zeolite slurry at a rate of 10 ml per minute. The stoichiometric ratio of moles of Si added as [(NH4)2SiE6] to the moles o' ~1 ~resent in the zeolite was 1.00. Following the addition of the fluoro-silicate solution, the slurry was digested for 48 hours under reflux conditions then filtered and thoroughly washed until te~ts of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses of the starting H+ mordenite and the product of the fluorosilicate treatment are shown in Table 7A, below:
Starting H+Treated H
MordeniteMordenite Na20, wt.% 0.29 0.22 (NH4)20, wt.% _ 1.35 A1203, wt.% 11.46 7.29 SiO2, wt.% 83.56 86.77 F2, wt.% - 3.36 SiO2/A1203 12.37 12.20 Na+/Al 0 04 0.05 NH4 /Al - 0.36 Cation Equivalent, M /Al 0.48 ~0.80 ~17~837 A comparison of the properties of the treated ze~lite with the starting H+ mordenite is shown in Table 7B, below:
Starting H Treated H
Mordenite Mordenite Chemical Si02/A1203 1?.. 37 20.20 Chemical M /Al 0 . 48 0 . 81 X-Ray Crystallinity (I) By Peak Intensity 100 120 (II) By Peak Area 100 102 Crystal Collapse Temp. C(DTA) 1025 .lo Exother~
Framework Infrared Asymmetric Stretch, cm 1085 NA
Symmetric Stretch, cm 1 792 NA
Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.225 0.300 The mole fractions of framework tetrahedra (TO2) are set forth for the starting H+-mordenite and the LZ-211 product in Table 7C below:
a) Mole fraction of Oxides,(TO2) H+-mordenite (Alo 126Sio 779r0 095)0;
LZ-711 (Alo 07~ b.794 0.127)o2 b) Mole fraction of aluminum removed, Ni - 0.047 c) % FraMework aluminum removed, N/a x 100 - 37 t) Change in defect structure factor, ~z - 0.032 e) Moles of silicon substituted per mole of aluminum removed,(N-~ztN) - O.32 As in the case of the preceding Example, proof of silicon substitution rests primarily on chemical analysis and absolute absorbance measurements in the hydroxyl stretching region of the infrared spectrum ( 3710 cm 1).
.
~7:~337 l2346-l The X-ray crystallinity was maintained. The peak area measurement shows the same value as the starting H~-mordenite and the peak intensity measurement indicates an increase in intensity due to peak sharpening. This suggests a more ordered structure than ~he starting H+-mordenite, the exact nature of which is not known at this time. The calculated unit cell ~alues make it quite certain that a substantial amount of silicon has replaced alu~inum in the framework. This alone could be the cause of increased intensity measurements in the X-ray powder pattern. A
sample taken after 24 hours of the fluorosilicate treatment had a SiO2/Al203 ratio of 19.1, a fluoride content of 3.5 wt.~/, and absolute absorbance at 3710 cm l of 0.330. Com-paring this sample to the sample described in Tables 6A, B and C, supra increasing the amount of fluorosilicate in the treatment step increases the amount of silicon substi-tution. Increasing the tigestion time also increased the degree of silicon substitution. It is apparently more difficult to substitute silicon into the framework structure of natural mortenite than it is to substitute it into the framework of synthetic mordenite.
Example 9 Fluorosilicate Treatment of NH4~-L Zeolite to Produce L7-212.
(a) Fifty gm of NaKL zeolite (SiO2/A1203 molar ratio of 6.03) was slurried with 500 ml of 1.0 molar NH4Cl solution at reflux for 16 hours and filtered. The exchange was repeated three times more and the product of the third exchange was washed with hot distilled water until tests of the wash water were negative when tested for chloride with AgNO3 solution From the product lO.0 gm (anhydrous ~7~837 12346-1 weight) was slurried in 100 ml of distilled water heated at 75C. A second solution of 50 ml containing 3.36 gm (NH4)2SiF6 was added to the NH4L-water slurry in 1 ml increments at a rate of 1 ml every five minutes. During the course of the fluorosilicate addition the temperature was maintained at 75C. The stoichiometric ratio of moles of Si added ~s [(~H4` -~iF~, to the mo1es of Al ~resent i~ the zèolite was 0.50. Following addition of the fluorosilicate solution the slurry was heated to 95C for 16 hours, then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions.
The chemical analyses for the starting NH4L and the product of the fluorosilicate treatment are shown in Table 8A, below:
Starting NH4L LZ-212 Product ~2~ wt,% 3.43 2.03 (NH4)20, wt,% 8.35 3.46 A1203, wt,% 19.22 11.15 SiO2,wt,% 68.31 81.38 F2, wt,% - 0,04 SiO2/A1203 6,03 12.39 K+/Al 0.19 0.47 NH4 /A1 0.85 0.61 Cation Equivalent, M /A1 1.04 1.08 A co~parison of the properties of the treated zeolite with the starting material is shown in Table 8B.
117~837 12346-1-C
TAaLE 8B
Bt~rting NH4L LZ-212 Pro~uct Chemic~l SiO2/A1203 6.03 12.3 Chemical M+/Al 1.05 1.0 X-RAy Cryst~llinity (I) By Peak Inte~sity 100 Excellent ~II) By Peak AleaNA NA
Cryst~1 Coll~pse Temp., C (DTA)900 950 Framework In~r~red ~symmetric Stretch, cm 11028 1109 Sy~m~tric Stretch, cm 1 769 782 Hydroxyl Infrared Absolute Ads~rb~nce at 3170 cm 1 0.085 0.1Y5 The frame work mole fractions are set forth in Table 8C
below for the starting NH4L and the LZ-212 product.
TA~LE ~C
a) Mole fraction of oxides ~TO2);
~L - (Alo.o24slo.724 oo.o36)o2 LZ-212 ~Alo, 128Slo. 790 C.082)02 b) Mole fraction of aluminum removed, N: - 0.112 c) Percent of framework aluminum removed, N/a x 100 - 47 d) Change in defect structure factor, ~z - 0.046 e) Moles of silicon substituted per mole of aluminum removed, (N- ~z)/N -0.57 The data show quite conclusively that under the conditions given, silicon substitutes for aluminum in the L
zeolite framework with a high degree of efficiency. X-ray crystallinity is maintained and the thermal stability is apparently increased. More im~ortantly, both the asymmetric stretch ~and and the symmetric stretch band in the framework infrared spectra increase following the treatment. This is a consistent with dealumination , 13~7~837 accompanied by silicon substitution in the framework. ~o absorption was observed at 3745 cm 1 due to occluded SiOH species and there is only a small increas~
in absolute absorbance at 3710 cm 1 which reflects the relative amount of hydrogen bonded OH groups in framework vacancies. Dealumination was nearly stoichiometric with the amount of fluorosilicate added.
(b) In a second experiment a fresh sample of NaY~L was obtained. Three hundred and seventy-two gm of NaKL zeolite (Si02/A1203 molar ratio of 5.93) was slurried with 1000 ml of 6 molar NH4Cl solution at reflux for 16 hours and filtered. The exchange was repeated twice more and the product of the third exchange was washed with hot distilled water until tests of the wash water were negative when testet for chloride with AgNO3 solution.
From the ammonium-exchanged product 10C gh (anhydrous weight) was slurried in 300 ml of distilled water heated at 75C. A second solution of 300 ml containing 33.94 ~m (NH4)2SiF6 was added to the NH4L-water slurry in 10 ml increments at a rate of 10 ml every five minutes.
During the course of the fluorosilicate addition the temperature was maintained at 75C. The stoichiometric ratio of moles of Si added as ['N~L)2';_r~ to the ~.oles of Al present in the zeolite was 0.50. Following addition of the fluorosilicate solution the slurry was maintained at 75C and digested for 24 hours, then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NH4L and the product of the fluorosilicate treatment are shown in Table 9A.
_ 7n _ 12346-l 1~71837 Startin~ NH4L LZ-212 K20, wt.% 3.51 2.66 (NH4)20, wt % 7.89 4.10 A1203, wt.% 19.42 11.52 SiO2, wt.% 67.80 ~9.62 F2, wt.~/o - 0.08 SiO2/Al203 5.92 11.73 K /Al 0.20 0.25 NH4 /Al 0.80 0.70 Cation Equivalent, M /Al1.00 0.95 A comparison of the properties of the treated zeolite with the starting NH4L is shown in Table 9B.
Starting NH4L LZ-212 Chemical SiO2/A1203 5.92 11.73 Chemical M /Al 1.00 0.95 X-2ay Crystallinity (I) By Peak Intensity 100 49 (II) By Peak Area 100 52 Crystal Collapse Tem.,C(DTA) 995 940, Framework Infrared Asymmetric Stretch, cm 1 1028 1108, 1031 Symmetric Stretch, cm 1 768 780 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.048 0.240 The framework mole fractions are set forth below in Table 9C for the starting NH4L and the LZ-212 product.
. . .
1~7~837 12346-1 a) Mole fraction of oxides (T02):
NH4L - (Alo 247Sio.733 0.020)2 LZ-212 - (Alo 13lSio 767 0.102~2 b) Mole fraction of aluminum removed, N; - 0.116 c) Percent of fra~eworK aluminum removed, N/a x lO0 _ 47 d~ Change in defect structure factor,~ z - 0.082 e) Moles of silic~n substituted per mole of aluminum removed, (N-~z)/N _ 0.29 It should be noted that the fluorosilicate digestion temperature in the present example was 75C while that in the previous example was at reflux. The degree of tealumination is the same for both digestion temperatures while the efficiency of silicon substitution is substan-tially retuced at the lower dlgestion temperature.
Example_lO
Fluorosilicate Treatment of Clinoptilolite to Produce LZ-219.
Twenty-five gm. of the natural mineral clinoptilolite (SiO2/A1203 molar ratio of lO.3) was slurried with 200 ml.
of l M. NH4Cl solution at reflux for one hour and filtered.
The exchange was repeated twice more and the product of the third exchange was washed with hot distilled water until tests of the wash water showed negative for chloride.
From the ammonium-exchanged product, 5.~ gm (anhydrous weight) was slurried in lO0 ml of distilled water heated at 95C. A second solution of 50 ml containing 1.17 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml. per 5 minutes. The stochiometrLc ratio of moles of Si added as [ (NH4)2SiF6] to the moles of Al in the zeolite was 0.5. Following the addit.on o' the fluorosilicate solution the slurry was digested for 7~
1~71837 three hours at 95C then thorou~hly washed until tests of the wash water proved ne~ative for both aluminum and flu~rid~
ions. The chemical analyses for the startin~ NH~ Clinopti-lolite and the product of the fluorosilicate treatment ar~
sho~ in Table lOA, below:
TABLE lOA
Starting NH4 Product Clinoptilollte Na20, wt.~/o 0.55 0.66 (NH4)20, wt.% 5.19 3.85 A123' wt.% 12.82 11.33 SiO2, wt.c 77.90 81.41 F2, wt.~/c - 0.53 SiO2/A1203 10.31 12.20 i~a+/Al 0.07 0.10 NH4 /Al 0.79 0.67 Cation Equivalent, M+/Al0.93 0.82 A comparison of the properties of the treated zeolite with the starting material is shown in Table lOB, below:
TABLE lOB
Starting NH Treated NH
Clinoptilol~te ClinoPtilo~ite Chemical SiO2/A1203 10.31 12.20 Chemical I~+/Al 0.93 0.83 X-Ray Crystallinity (I) By Peak Intensity 100 60 (II) By Peak Area 100 60 Crystal Collapse Temp.,C(DTA) 530 533 Framework Infrared Asymmetric Stretch, cm 1 1062 1086 Symmetric Stretch, cm 1 795, 778 796, 778 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.055 0.135 .. . . .
117~B37 The framework mole fractions are set forth in Table lOC
below for the starting NH4-Clinoptilolite and the product.
TABLE lOC
a) ~Iole fraction of oxides (T02); NH4 Clino.- -I
(Alo 159sio.81~~~.023)2 Product (Alo l33Sio.810 0.057)2 b) Mole fraction of aluminum removed, N; - 0.026 c) % of framework aluminum removed; N/a x lO0 - 16 d) Change in defect structure factor, ~z - 0.034 From the data it would appear that rnainly dealumination resulted from the treatment of NH4 Clinoptilolite with the (NH4)2SiF6 at 95C. However the efficiency of dealumination i9 low, indicating that the sites in the framework where the aluminum atoms are located are relatively inaccessible, or that aluminum atoms in the particula~ environment of the clinop~ilolite framework are extremely stable. Accordingly when the experiment is repeated using more rigorous condi-tions, preferred LZ-21~ products within the scope of the preferred co~positions cc tho present invention are formed.
Exam~le 11 Fluorosilicate Treatment of Chabazite to Produce LZ-218 Twenty-five grams of the natural mineral chabazite (SiO2/A1203 molar ratio of 8.5) was slurried with 200 ml of 2 molar NH4Cl solution at-refluY. for one hour and filtered. The exchange was repeated twice more and the product of the third exchange was washed with hot distilled ater until tests of the wash water showed negative for chloride.
1~7~33~7 From the ammonium exchanged prod~ct, 5.0 gm (anhydr~us weight) was slurried in 100 ml of distilled water heated at 95C. A second solution of 50 ml containing 2.60 ~m (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml per five minutes. The stoichiometric ratio of moles of silicon added as l(N~.4)~Si~6] to the moles of aluminum present in the zeolite was 1.00. Following the addition of the fluorosilciate solution the slurry was digested for three hours at 95C then thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for tne starting NH4 chabazite and the product of the fluorosilicat~
treatment are shown in Table llA, below:
TABLE llA
Starting NH4- LZ-218 Chabazite Product Na20, wt.% NA 0.85 (NH4~20, wt.% 4.98 3.30 A1203, wt.% 14.83 12 05 SiO2, wt.% 74.51 78.98 F2, wt.% NA 0.39 SiO2/A1203 8.52 11.13 Na tAl NA 0.12 NH4 /Al 0.66 0.54 Cation Equivalent, M /Al 0.66 0.94 A comparison of the properties of the treated zeolite with the starting material is shown in Table llB, below:
117~837 TABLE llB
Starting NH4 LZ-218 Chabazite Product Chemical SiO2/A1203 8.52 11.13 Chemical M /Al 0.69 0.94 X-Ray Crystallinity (I) By Peak Intensity 100 164 (II) By Peak Area 100 106 Crystal Collapse Temp.,C(DTA) Sinter 940C Exotherm 930C
Framework Infrared Asymmetric Stretch, cm 1 1042 1096 Symmetric Stretch, cm 1 771 785 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.0750.145 The framework mole fractions are set forth in Table llC
below for the starting NH4 chabazite and the LZ-218 products TABLE llC
a~ Mole fraction of framework oxides (T02); NH4 Chabazite -(Alo 184sio.784 0.032)2 (Alo 143Sio.7gs 0.062)2 b) Mole fraction of aluminum removed, N- 0.041 c) % framework aluminum removed; N/a x 100 - 22 t) Change in defect structure factor , ~z, - 0.030 e) Moles of silicon substituted per mole of aluminum removed; (N-4z)/N - 0.27 The data indicate that silicon has replaced aluminum in the chabazite framework. The efficiency of aluminum removal is relatively low compared with the Y, L and mordenite zeolites, and comparable to that observed in the case of clinoptilolite. However with chabazite, silicon does replace the removed aluminum in the framework as shown by the shift 1~7~837 of both the asymmetric stretch band and the symmetric stretch band of the framework infrared spectrum to higher wavenumbers Additionally, no evidence was found to indicate occlusion of amorphous SiOH species which would account for the increased silicon content in the zeolite. The increase in X-ray peak intensity while the peak area remains constant is taken as further evidence of silicon substitution in the framework.
Example 12 Fluorosilicate Treatment of Erionite to Produce LZ-220.
A 5.0 gm (anhydrous weight) sample of an ammonium exchanged natural erionite was slurried in lOOml. of distilled water heated at 95C. A second solution of 50 ml containing 1.60 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml per minute.
The stoichiometric ratio of moles of Si added as ~N~14)~51P6]
to the ~oles of Al present in the zeolite was 0.54.
Following the addition of the fluorosilicate solution the slurry was tigested for three hours at 95C then thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NH4 Erionite and the product of the fluorosilicate treatment are shown in Table 12A, below:
Starting NH4 Product Erionite LZ-220 Na20, wt.% 0.35 0.24 (NH4)20, wt.% 5.75 3.54 A1203, wt.% 16.80 13.24 SiO2, wt.% 68.93 76.26 F2, Wt.% - 0.39 .
1~71837 TABLE 12A ¢ontinued) Starting NH4Product Erionite LZ-~'J
SiO2/A1203 6.96 9.77 Na /Al 0.03 0,03 1 0.67 0.52 Cation Equivalent, M /Al 0.91 0.79 A comparison of the properties of the treated zeolite with the starting material is shown in Table 12B, below:
Starting NH4Product Erionite LZ-220 Chemical SiO2/A1203 6.96 9.77 Chemical M /Al 0.91 0.79 X-Ray Crystallinity (I) By Peak Intensity 100 172 (Il) By Peak Area 100 150 Crystal Collapse Temp.,C(DTA) 976 995 Framework Infrared Asymmetric Stretch, cm 1 1052 1081 Symmetric Stretch, cm 1 781 784 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0 0700.160 The framework mole fractions are set forth in Table 12C
below for the starting NH4-Erionite and the product zeolite.
a) Mole fraction of framework oxides, (T02);
NH4 Erionite - (Alo 217Sio,753 0 030)2 Product LZ-22~ ~Alo 158sio.774 0.068)2 b) Mole fraction of aluminum removed, N - 0.059 c) % of framework aluminum removed, N/a x 100 - 27 .. . . .
1~7~837 d) Change in defect structure factor, ~z - 0.038 e) Moles of silicon substituted per mole of aluminum removed, (N-~z)/N _ 0.36 The data establish the feasibility of substitutin~ silicon for framework aluminum in erionite by the method of the present invention, Vsing the conditions described, however, the efficiency of aluminum removal and of silicon substi-tution are relatively low. Using more rigorous reaction conditions results in the formation of a preferr~d LZ-"20 product within the scope of the novel compositions of the invention.
Example 13 Fluorosilicate Treatment of Offretite to Produce LZ-217.
Approximately 50 grams of synthetic TMA offretite was slowly calcined to 550C and held 24 hours. The calcined offretite (Si02/A1203 molar ratio of 9.2~ was slurried with 300 ml of 1.3 molar NH4 Cl solution at reflux for one hour and filtered. The exchange was repeated twice more and the product of the third exchange was washed with hot distilled water until tests of the wash water showed negative for chloride.
From the ammonium exchanged product, 5.0 ~m (anhydrous weight) was slurried in 100 ml of distilled water heated at 95C. A second solution of 50 ml containing 1.25 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml per five minutes, The stoichiometric ratio of moles of silicon added as [!N.L4)2SiF6] to ~he moles of aluminum present in the zeolite was 0.51. Following the addition of the fluorosilicate solution the slurry was digested for three hours at 95C then thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NH4 Offretite and the product of the fluorosilicate ~ 7~837 12346-1 treatment are shown in Table 13A, bel~w:
TABLE l3A
Startin~ NH - LZ-217 Offretite 4 Product K20, wt.% 2.48 1.47 (NH4)20, wt.% 5.31 2.72 A1203, wt.% 14.05 8.27 SiO2, wt.% 76.15 84.71 F2, wt.% - 0.12 SiO2/A1203 9.20 17.38 ~ /Al 0.19 0.19 NH4 /Al 0.74 0.64 Cation Equivalent, M /Al 0.93 0.84 A comparison of the properties of the treated zeolite with the starting material is shown in Table 13B, below:
Startin~ NH - LZ-217 Offretite 4 Product Chemical SiO2/A1203 9.20 17.38 Chemical M+/Al 0.93 0.84 X-Ray Crystallinity (I) By Peak Intensity 100 59 (lI) By Peak Area 100 60 Crystal Collapse Temp.,C(DTA) 1001 1043 Framework Infraret Asymmetric Stretch, cm 11083 1094 Symmetric Stretch, cm 1789 793 Hydroxyl Infrared Absolute Absorbance at 3710 cm 1 0.140 0.239 The framework mole fractions are set forth in Table 13C
below for the startin~ NH4 offretite and the LZ-217 product.
1~71~37 12346-1 TABLE 13_ a) M~le fraction of framework oxides (TO2); NH4 Offretite -(A1~ 168Sio 773 0.059)2 LZ-217-(Alo 093sio.806 0.101)2 b) Mole fraction of aluminum removed; N - 0.075 c) % framework aluminum removed; N/a x lOO - 45 d) Change in defect structure factor, ~z - 0. 042 e) Moles of silicon substituted per mole of aluminum removed, (N-~z) /N - O . 44 The data show that dealumination and silicon substitution do occur in the erionite framework as a result of the fluorosilicate treatment. Some degradation of the structure seems apparent rro~ the X-ray crvstallinit,v data.
However, oxygen adsorption values for the starting NH4 Offretite and the treated product are nearly identical (16-17 wt.% 2 at 100 Torr and -183C). The efficiency of tealumination under the described conditions is quite high and the efficiency of silicon substitution can be increased with longer digestion times.
Example 14 Fluorosilicate Treatment of Zeolite W.
Eight gm of synthetic zeolite W (Si02/A1203 molar ratio of 3.66) was slurried in 100 ml of 1;1 molar NH4Cl solution at reflux for one hour and filtered. The exchange was repeated twice more, the third and final exchange being carried out over 16 hours. The product was then washed with hot distilled water until tests of the wash water showed neRative for chloride.
From the NH4W product, 5.0 gm (anhydrous weight) was slurried in 100 ml distilled water heated at 95~C.
A second solution of 50 ml containing 2.21 gm (NH4)2SiF6 1~7~33~
wad added to the slurry in 2 ml increments at a rate of 2 ml every five minutes. During the course of the fluoro-silicate addition the slurry temperature was maintained at 95C. The stoichiometric ratio of moles of Si added as [(NH4)2SiF~7 to the moles of Al present in the zeolite was 0.49. Following addition of the fluorosilicate solution, the slurry was digested for three hours at 95C then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions.
The chemical analyses for the starting NH4W and the product of the fluorosilicate treatment are shown in Table 14A, below:
Starting NH4W Trested NH
K20, wt.% 0.81 0.57 (NH4)20, wt.% 11.37 4.19 A1203, wt.~/o 25.99 11.88 SiO2, wt.% 59.40 81.67 F2, wt.% - 0.62 SiO2/A1203 3.88 11.67 K /A1 0.03 0-05 NH4~/Al 0.86 0.69 Cat$on Equivalent, M /Al 0.89 0.79 A comparison of the properties of the treated zeolite with the starting material is shown in Table 14B, below:
_ ~ _ 1~7~&~37 TABLE l~B
Startinq NH4W Treated NH4W
Chemica~ SiO2/A12~3 3.88 11.67 Chemical Ml/Al 0.89 0.79 X-~ay Crystallinity ~) By Peak Intensity 100 ~7 ~ By Peak A*ea 100 3S
Unit Cell ~a~) in A 20.2~6 20.145 Crystal Collapse ~emp., ~C (DTA) 1031 1025 Framework ~nfrared Asymmetric Stretch, cm 1 1020 lOB4 Symmetric Stretch, cm~l 780 ~88 Hydroxyl Infrared Abso'ute Absorbance at 3710 cm 1 o.o75 0.310 The framework mole fractions are set forth in Table 14C
below for the starting NH4W and the product zeolite.
a) Mole fraction of framework oxides (T02);
NH4W - (Alo 32gSio~639 0~032)2 Product(A10 127sio~74l 0.131)2 b) Mole fraction of sluminum removed; N - 0.202 c) % of framework aluminum removed; N/a x lO0 - 61 d) Change in defect structure factor; ~z - 0.099 e) Moles of silicon substituted per mole of alumin~n removed;(N-~z)/N - 0.51 The tata establishes the feasibility of substituting silicon for framework aluminum in zeolite W using the process of the present invention. The X-ray crystallinity tata couplet with some preliminary sdsorption tata, however, inticate that an undue amount of crystal tegradation occurred using the specifiet reaction conditions, with the consequent protuct$on of a zeolite which toes not qualify as preferred LZ-216.
Evidence for silicon substitution is established by the shift of framework infrared absorption bands to higher wavenumbers ~7~837 and the relative size of the broad absorption band in the hydroxyl .egion of the infrared spectrum which does not correlate well with the high level of dealumination.
Chemical analysis data of both the solid and the liquid phases of the reaction showed that silicon was indeed incorporated into the zeolite. With no increased absor-bance at 3745 cm 1 of the infrared spectrum indicative of amorphous SiOH species as additional evidence, it must be concluded that siliccr.was incorporated into the zeolite framework during the treatment.
The cause of the structure degradation is believed to be the extensive dealumination of the framework without adequate silicon substitution. Accordin~ly the reactiD~ shoul~, in order to produce LZ-216, be carried out in the presence of a buffer solution such as ammonium acetate. As a general proposition the higher the aluminum content of the starting zeolite, the greater the need for buffering.
When this is tone, preferred LZ-216 results as the product.
Exam~le 15 Fluorosilicate Treatment of Zeolite Rho.
A sample of NH4Rho zeolite which contained a sparingly soluble chloride salt was extracted for a period of ei~ht days in a Soxhlet extraction apparatus. From the washed NH4 Rho zeolite 25.0 gm (anhydrous weight) was slurried in 200 ml distilled water heated at 75C. A second solution of 100 ml containing 8.5 gm (NH4)2SiF6 was added to the slurry in 3 ml increments at a rate of 3 ml every five minutes. During the course of the fluorosilicate addition the slurry temperature was maintained at 75C. The stoichiometric ratio of moles of Si added as [!~H4)~LF5] to ~7~837 the moles of Al present in the zeolite was 0.50. Following addition of th fluorosilicate solution, the slurry was disqested for 24 hours at 75C then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions. The chemical analyses for the starting NHg Rho and the product of the fluoro-silicate treatment are shown in Table 15A, below:
Starting NH4-Rho Treated NH4-Rho Cs20, wt. ~ 3.02 2.07 ~NH4)20, wt t 9.53 4.48 A123' t- ~ 19.30 11.03 SiO2, wt. ~ 6~.33 80.34 F2, wt. t - 0.06 Si2/A1203 5.92 12.36 Cs/Al 0.06 0.07 NH4~/A1 0.81 0.80 Cation Equivalent, Ml/A1 0.ô7 0.86 A compari~on ot the properties of the treated zeolite with tne startlng NH4 Rho is ~hown ln Table 158, below.
TA~LE 150 Starting NH4-Rho Tre~ted NH4-Rno Chemlcal 6iO2/A12035.92 12.36 Chemlcal ~/Al O.ô7 0.86 X-Ray Cryst~llinity ~I~ By Peak Intensity100 70 (II) By Peak Area 100 70 Unit Cell (aO) in A14.99114.927 Cry6tal Collapse Temp., C ~DTA) 975975, 1165 Framework Infrared ~ymmetrlc Stretch, cm 11049 1100, 1055 6ymmetrlc Stretch, cm 1~01 800 NydroKyl Int'r~red Absolute Adsorb~nce at 3710 cm 10.0750.0340 ~71837 12346-1-C
The framework tetrahedral mole, fractions are set forth in Table 15C below for both the starting NH4 ~ho and the product zeolite.
Table 15C
~) MOle fr~cti~n of fr~ework oxides (T02~;
NH4Rh~ - (Alo.245Sl~.7? ~0.~31) ~
Pr~uct- (Alo ll~SIo.73 ~ .144)2 b) Mole fr~cti~n o~ ~luminum re~oved, N: - 0.126 c) Percent of fr~mework aluminum remo~ed, N/a x 100 - 51 d) Change in deect ~tructure factor, ~z - 0.113 e) Moles ~f ~ilicon substituted yer mole of luminu~ rem wed, ~N- ~z)~N - 0.10 From the calculated unit cell compositions it appears that a relatively small amount of silicon was incorporated into the zeolite Rho framework during the treatment. This is consistent with the very large shift of the asymmetric stretch absorption band of the framework infrared region and the lack of shift for the symmetric stretch band. The efficiency of dealumination is high but under the conditions employed, the ef~iciency of silicon substitution is low. A LZ-214 product within the scope o~ the preferred novel compositions of this invention and having the characteristic crystal structure of zeolite Rho is produced by digesting at a higher temperature and employing additional buffering agents to protect the zeolite from acid attack.
Example 16 Preparation of LZ-210.
Ten gm. (anhydrous weight) of ammonium zeolite Y
(SiO2/A1203 molar ratio - 4.93) were slurried in 100 ml of 3.4 molar ammonium acetate solution at 75C. A 50 ml solution of water containing 4.63 gm Li2SiE6 2~20 was ~C
~L3l718~7 added to the zeolite slurry in 1 ml incremenes at an addi-tion rate of 1 ml. every 5 minutes. Followin~ addition o~
the Li2SiF6 solution, the reaction mixture was dip,ested 17 hours at 75C, with stirring. After the di~estion period the reaction mixture was filtered and the filter cake thorou~hly washed with distilled H20 until tests of the wash water proved negative for both fluoride and aluminum ion.s. The product was dried two hours at 110C
in air. The chemical and other analyses for the starting NH4Y zeolite and the LZ-210 product zeolite are set forth below.
NH4YLZ-210 Product Na20-wt.% 2.5 0.6 (NH4)20-wt./o 9.5 3.7 Li20-wt.~/o - 0.4 A123 wt.% 22.2 9.7 SiO2-wt.% 64.4 85.0 SiO2/A1203(molar) 4-93 14.80 Na /Al 0.19 0.10 NH4+1A1 0.84 0.74 Li /Al - 0.13 Cation Equivalent (M /Al) 1.03 0.98 X-Ray Crystallinity:
(I) By Peak Intensity 100 83 Unit Cell Dimension(aO) 24.712 24.393 Framework Infrared:
Asymmetric Stretch, cm-l 1015 1061 Symmetric Stretch, cm 1 787 818 Hydroxyl Infrared:
Absolute Absorbance at 3710 cm 1 _ 0.160 Defect Structure Factor,z0.000 0.068 _ R7 -1~718~7 12346-l The framework mole fractions of tetrahedra are set forth below for ~he startin~ NH4Y and the LZ-210 product.
a) Mole fraction of framewor~ oxides (T02);
NH4Y (Alo 2g9SiO.711 0)~2 LZ-210 (Alo lllSio.821 0.068)2 b) Mole fraction of aluminum removed; N - 0.178 c) % framework aluminum removed; N/a x lO0 - 62 d) Change in defect structure factor; ~z - 0.068 e) Moles of silicon substituted per mole of aluminum removed; (N-~z)/N - O.62 In addition to the above described properties, the crystal collapse temperature of the LZ-210 product as measured by the standard DTA procedure was at 1128C.
The untreated NH4Y crystal collapse temperature measured by the same DTA technique was at 890C.
Example 17 Preparation of LZ-210.
Ten g~. (anhydrous weight) of ar,~or.ium zeolite Y
(SiO2/A1203 ~olar ratio - 4.93) were slurried in 100 ml of 3.4 molar am~onium acetate solution at 75C. Reagent grate K2SiF6 (5.32 gm) crystals were added directly to the slurry. The reaction mixture was digested at 75C
with stirring for two days, after which it was filtered and the filter cake thoroughly washed with hot distilled water until tests of the wash water proved negative for both fluoride and aluminum ions. The X-ray powder pattern obtained on the dried product did not show any extraneous peaks indicative of impurities, precipitated in the zeolite matrix. The chemical and other analyses for the starting NH4Y zeolite and the LZ-210 product zeolite are set forth below.
~71837 12346-~
NH4Y LZ-210 Pr~duct Na20-wt.% 2.5 1.2 (NH4)20-wt. D/~ 9.5 1.6 K20-wt.% _ 5.6 A1203-wt . ~/o 22 . 2 11. 4 SiO2-wt.% 64.4 78.7 SiO2/A1203(molar) 4.93 11.72 Na /Al 0.19 0.18 NH +/Al 0.84 0.27 K /Al ~ 0 53 Cation Equivalent(M /Al) 1.03 0.98 X-Ray Crystallinity:
By Peak Intensity lO0 44 Unit Cell Dimension (aO) 24.712 24.514 Framework Infrared:
Asymmetric Stretch, cm 1 1015 1047 Symmetric Stretch, cm 1 787 799 Hytroxyl Infrared:
Absolute Absorbance at 3710 cm 1 _ 0. 210 Defect Structure Factor, z 0.000 0.089 The framework mole fractions of tetrahedra are set forth below for the starting NH4Y and the LZ-210 product.
a) Mole fraction of framework oxites (T02);
NH4Y - (Alo.289sio.7ll 0) 2 LZ-210 - (Al~ 133Sio.773 0~o89)o2 b) Mole fraction of aluminum removed; N - 0.156 c) V/o framework aluminum removed; N/a x 100 - 54 d) Change in defect structure factor; ~z - 0. 089 e) Moles of silicon substituted per mole of aluminum removed; (N-az)/N - O.43 ~7~37 12346-1 In addition to the above described properties, the crystal collapse temperature of the LZ-210 product as measured by the standard DTA procedure was at 1072C.
The untreated NH4Y crystal collapse temperature measured by the same DTA technique was at 890C.
Example 18 Ten gm. (anhydrous weight) of ammonium zeolite Y
(SiO2/A1203 ratio = 4.93) were slurried in 100 ml of 3.5 molar ammonium acetate solution at 75C. A 50 ml solution of water containing 6.63 gm MgSiF6-6H20 was added to the slurry in increments of 1 ml, at a rate of 1 ml every 5 minutes. Following addition of the MgSiF6 solution the reaction mixture was digested 17 hours at 75C, with stirring. After the digestion period, the reaction mixture was filteret and the filter cake thoroughly washed with tistillet water until tests of the wash water proved negative for both fluoride and aluminum ions. The X-ray powder pattern obtained on the product showed the presence of a substantial amount of (NH4)M~AlF6 in the product. The fluoride containing product was Soxhlet extracte~ w'th wa~e~
for 60 hours with the result that a negligible amount of NH4MgAlF6 was removed from the product. Wet chemical analyses and X-ray powder tiffraction both indicated that the protuct was a mixture of ~5% zeolite and 15% NH4MgAlF6.
The chemical ant other analyses for the starting NH4Y zeolite ant the LZ-210 protuct zeolite are set forth below:
~ 837 12346-1 As Prepared:
NH4Y LZ-210 Product Na20, wt.% 2.5 0.6 (NH4)20, wt.% 9.5 3.2 MgO, wt.% - 6.9 A1203, wt.% 22.2 15.2 SiO2, wt.% 64.4 65.6 SiO2/A1203(molar) 4.93 7.30 F2 ~ Wt . % none 9.2 __ _ _ Corrected for 15 wt./, NH4MgAlF6:
SiO2/A1203 4.93 9.93 Cation Equivalent(M /Al)1.03 1.12 X-ray Crystallinity intensity 100 100 Unit Cell Dimension(aO)24.712 24.454 Framework Infrared:
Asymmetric Stretch, cm 1 1015 1045 Symmetric Stretch, cm 1787 811 Hydroxyl Infrared:
Absolute absorbance @3710cm 1 _ 0 077 Defect Structure Factor, z 0,000 0 033 The framework mole fractions of tetrahedra are set forth below for the starting NH4Y and the LZ-210 product which has been corrected for the presence of 15 wt.% NH4MgAlF6.
a) Mole fraction of framework oxides(T02);
NH4Y - (A10.289SiO 711 0.000 2 LZ-210 - (Alo,l61Sio,806 0.033 2 b) Mole fraction of aluminum removed; N - 0.128 c) % framework aluminum removed; N/a x 100 - 44 d) Change in defect structure factor; ~z - 0.033 e) Moles of silicon substituted per mole of aluminum removed; (N-az)/N _ 0 74 ,., . ql ~7~837 12346-l Exam~le 19 Fluorosilicate Treatment of NH4~-Omega Zeolite to Produce LZ-213.
(a) A 5.0 gm. sample of Na,TMA-Omega, which had been calcined to remove the tetramethylammonlum catlon~ ar.~ t~lDr ~n-exchanged with ammonium cations, was slurried in 100 ml.
distilled water heated to 95~C. A second solution of 50 ml containing 1.48 gm (NH4)2SiF6 was added to the slurry in 2 ml increments at a rate of 2 ml every 5 minutes.
During the course of the fluorosilicate addition, the slurry temperature was maintained at 95C. The stoichiometric ratio of moles of Si added as [(~H4)2SiF6~ to the moles of Al present in the zeolite was 0~55. Following addition of the fluorosilicate solution, the slurry was digested 3 hours at 95C, then filtered and thoroughly washed until tests of the wash water proved negative for both aluminum and fluoride ions.
The resulting product was only 30~ crystalline indicating that the described treatment conditions were too rigorous for the omega structure. No further charac-terization was obtained with this sample.
tb) A second sample of ammonium-exchanged-calcined TMA
Omega zeolite, weighing 1.5 gm, was slurried in 200 ml of 3.4 molar ammonium acetate solution and heated to 75C.
A second solution of 50 ml containing 0.36 gm (NH4)2SiF6 in water was added in one ml increments at a rate of one m~ every minute. During the course of the fluorosilicate addition, the slurry temperature was maintained at 75~C.
The stoichiometric ratio of moles of silicon added as [(NH4)2SiF6] to the moles of aluminum present in the zeolite _ 92 -~ ~'73~83,7 was 0.5. Followin~ addition of the fluorosilicate, th~
slurry was digested for 3 hours at 75~C, then filter~d and thoroughly washed until tests of the wash water proved negative for both aluminum an~ fltloride lons.
The chemical analyses for the starLin~ ~H4-Omega and th~
product of the fluorosilicate treatment are shown in Table 16A, below:
Starting NH4+-Omega LZ-213 Product ~a20, wt.-~ -- 0.16 (NH4)20, wt.-% 8.26 7.93 A1203, wt.-~ 19.56 18.35 SiO2, wt.-% 71.48 72.30 F2, wt.-Z -- 0.18 SiO2/A1203(molar) 6.20 6.67 Na+/Al -- 0.01 NH4 /Al 0.83 0.85 Cation Equivalent, M+/Al0.83 0.86 The comparison of the properties of the treated zeolite with the starting material is shown in Table 16B, below:
Starting NH4+-Omega LZ-213 Product X-Ray Crystallinity (I/Io) 100 109 Framework Infrared Asymmetric stretch, cmIl 1040 1045 Symmetric stretch, cm 810 812 Hydroxyl Infrared Absolute Absorbance at 3710 cm-l 0.039 0.061 Defect Structure Factor, z 0.017 0.026 _ 9~ _ ~'7~ ~ 37 The framework mole fractions are set forth below for the starting NH4 -Omega and the LZ-213 product.
a) Mole Fraction of-Oxides(To2) NH4 -Omega (Alo 239Sio.744 0.017) 2 (Alo 225Sio.749 0.026)o2 b) Mole fraction of aluminum removed, N - 0.014 c) Percent of framework alumimlm r~moved, (~/a) x 100 - 6 d) Change in Defect Structure Factor, ~z - 0.009 e) Moles of silicon substituted per mole of aluminum removed, (~-~z)/N - 0.36 This example is Sllustrative of a zeolite sample that has been both treated too harshly (high temperature and pH, concentrations) causing excessive crystal degradation,and too mildly such that the dealu~.ination was too slow and silicon substitution could not occur to a substantial level even though the efficiency of silicon substitution was nearly 40%.
The novel zeolite compositions of the present invention are useful in all adsorption, ion-exchange and catalytic processes in which their less siliceous precursors have heretofore been suitably employed. In general, because they are more highly siliceous than their precursors they are not only more thermally and hydrothermally stable than those prior known materials but also have increased resistance to~;ard acidic agents such as mineral and organic acids, S02, S03,~Cx and the like. These new zeolites are thus highly useful as selective adsorbents for these materials from, for example, gas streams containing same in contact sulfuric acid plants. Also since their crystal structures are notably 1~ in defect structure and the g ~
~7~1837 zeolitic cations are ion-exchangeahle for other cation species, both metallic and non-metallic, these zeolite compositions are readily tailored by known methods to suit the requirements of a broad spectrum of catalyst com?osi-tions, particularly hydrocarbon conversion catalysts.
The non-metallic cation sites can also be thermally deca-tionized in the known manner to produce the highly acidic zeolite forms favored in most hydrocarbon conversion reactions.
The novel zeolites of this invention can be compounded into a porous inorganic matrix such as silica-alumina, silica-magnesia, silica-zirconia, silica-aluminia-thoria, silica-alumina-magnesia and the like. The relative propor-tions of finely divided zeolite and inorganic matrix can vary widely with the zeolite content ranging from about 1 to 90 percent by weight, preferably from about 2 to about 50 percent by weight.
Amo~g the hydrocarbon conversion reactions catalyzed by these new compositions are cracking, hydrocracking, alkylation of both the aromatic and isoparaffin types, isomerization including xylene isomerization, polymerization, reforming, hydrogenation, dehydrogenation, transalkylation and dealkylation, and catalytic dewaxing.
Using these zeolite catalyst compositions which contain a hydrogenation promoter such as platinum or palladium, heavy petroleum residual stocks, cyclic stocks and other hydrocrackable charge stocks can be hydrocracked at temperatures in the range of 400F to 825F using molar ratios of hydrogen to hydrocarbon in the range of between 2 and 80, pressures between 10 and 3500 p.s.i.g., and a liquid hourly space velocity (LHSV) of from 0.1 to 20, preferably 1.0 to 10.
oc _ 1~7~837 The catalyst compositions employed in hydrocrackin~
are also suitable for use in reforming processes in which the hydrocarbon feedstocks contact the catalyst at tempera-tures of from about 700F to 1000F, hydrogen pressures of from 100 to 500 p.s.i.g., LHSV values in the ran~e of 0.1 to 10 and hydrogen to hydrocarbon molar ratios in the range of 1 to 20, preferably between 4 and 12.
These same catalysts, i.e. those containing hydro-genation promoters, are also useful in hydroisomerization processes in which feedstocks such as normal paraffins are converted to saturated branched chain isomers. Hydroiso-merization is carried out at a temperature of from about 200F to 600F, preferably 300F to 550F with an LHSV
value of from about 0.2 to 1Ø Hydrogen is supplied to the reactor in ad~.ixture with the hydrocarbon feedstoc~
in molar proportions (H/Hc) of between 1 and 5.
At somewhat hi~her temperatures, i.e. from about 650F
to 1000F, preferably 850F to 950F and usually at some-what lower pressures within the range of about 15 to 50 p,s,i.g,, the same catalyst compositions are used to hdyro-isomerize normal paraffins, Preferably the paraffin feed-stock comprises normal paraffins having a carbon number range of C7-C20, Contact time between the feedstock and the catalyst is generally relatively short to avoid unde-sireable side reactions such as olefin polymerization and paraffin cracking, ~HSV values in the range of 0,1 to 10, preferably 1,0 to 6,0 are suitable.
The $ncrease in the molar SiO2/Al203 ratios of the present zeolite compositions favor their use as catalysts in the conversion of alkylaromatic compounds, particularly the catalytic disproportionation of toluene, ethylene, 7~337 trimethyl benzenes, tetramethylbenæenes and the like. In the disporportionation process isomerization and trans-alkylation can also occur. Advantageously the catalyst form employed contains less than 1.0 weight percent sodi~m as Na20 and is principally in the so-called hydrogen cation or decationized form. Group VIII noble metal adjuvents alone or in conjunction with Group VI-B metals such as tungstem, molybdenum and chromium are preferably included in the catalyst composition in amounts of from about 3 to 15 weight-% of the overall composition. Extraneous hydro-gen can, but need not be present in the reaction zone which is maintained at a temperature of from about 400 to 750F, pressures in the range of 100 to 2000 p.s.i.g. and LHSV values in the range of 0.1 to 15.
Catalytic cracking processes are preferablv carried out using those zeolites of this invention which have SiO2/
A1203 molar ratios of 8 to 12, less than 1.0 weight-%
Na20 and feedstocks such as gas oils, heavy naphthas, deasphalted crude oil residua etc. with gasoline being the principal desired product. The decationized form of the zeolite and/or polyvalent metal cationic form are advantageously employed. Temperature conditions of 850 to 1100F, LHSV values of 0.5 to 10 and pressure conditions of from about 0 to 50 p.s.i.g. are suitable.
Dehydrocyclization reactions employing paraffinic hydrocarbon feedstocks, preferably normal paraffins having more than 6 carbon atoms, to form benzene, xylenes, toluene and the like are carried out using essentially the same reaction conditions as for catalytic cracking. The preferred form of the zeolite employed as the catalyst is ~ 7~37 12346-l that in which the cations are principally metals of ~,roup II-A and/or II-B such as calcium, strontium, ma~nesium.
Group VIII non-noble metal cation can also be employed such as cobalt and nickel.
In catalytic dealkylation wherein it is desired to cleave paraffinic side chains from aromatic nuclei without substantially hydrogenating the ring structure, relatively high temperatures in the range of about 800-1000F are employed at moderate hydrogen pressures of about 300-lO00 p.s.i.g , other conditions being similar to those described above for catalytic hydrocracking. Preferred catalysts are of the relatively non-acidic type described above in connection with catalytic dehydrocyclization. Particularly desirable dealkylation reactions contemplated herein include the conversionof methylnaphthalene to naphthalene and toluene and/or xylenes to benzene.
In catalytic hydrofining, the primary ob;ective is to promote the selective hydrodecomposition of organic sulfur and/or nitrogen compounds in the feed, without substantially affecting hydrocarbon molecules therein. For this purpose it is preferred to employ the same general conditions described above for catalytic hydrocracking, and catalysts of the same ~eneral nature described in connection with dehydrocyclization operations. Feedstocks include gasoline fractions, kerosenes, jet fuel fractions, diesel fractions, light and heavy gas oils, deasphalted crude oil residua and the like any of which may contain up to about 5 weight-percent of sulfur and up to about 3 weight-percent of nitrogen.
Similar conditions can be employed to effect hydro-fining, i.e., denitrogenation and desulfuriæation, of ~ 3 ~ 12346-1 hvdrocarbon feeds containing substantial proportions of organonitrogen and organosulfur compounds. As observed by D.A. Young in ~.S.P. 3,783,123, it is generally recog-nized that the presence of substantial amounts of such constituents markedly inhibits the activity of catalysts for hydrocracking. Consequently, it is necessary to operat~
at more extreme conditions when it is desired to obtain the same degree of hydrocracking conversion per pass on a relatively nitrogenous feed than are required with a feed containing less organonitrogen compou~.ds. Conseque..~
the conditions under which denitrogenation, desulfuriza~ion and/or hydrocracking can be most expeditiously accomplished in any given situation are necessarily determined in view of the characteristics of the feedstocks in particular the concentration of organonitrogen compounds in the feed-stock. As a result of the effect of organonitrogen compounds on the hytrocracking activity of these compositions it is not at all unlikely that the conditions most suitable for denitrogenation of a given feedstock having a relatively high organonitrogen content with minimal hydrocracking, e.g., less than 20 volume percent of fresh feed per pass, might be the same as those preferred for hydrocracking another feedstock having a lower concentration of hydro-cracking inhibiting constituents e.g., organonitrogen compounds. Consequently, it has become the practice in this art to establish the conditions under which a certain feed i8 to be contacted on the basis of preliminary screen-ing tests with the specific catalyst and feedstocks.
Isomerization reactions are carried out under conditions similar to those described above for reforming, using some-what more acidic catalysts. Olefins are preferably _ 99 _ ~ 7~337 l2346 l isomerized at temperatures of 500-900F, while paraffins, naphthenes and alkyl aromatics are isomerized at tempera-tures of 700-1000F. Particularly desirable isomerization reactions contemplated herein include the conversion of n-heptane and/or n-octane to isoheptanes, iso-octanes, butane to iso-butane, methylcyclopentane to cyclohexane, meta-xylene and/or ortho-xylene to paraxylene, l-butene to 2-butene and/or isobutene, n-hexene to isohexene, cyclo-hexene to methyl-cyclopentene etc. The preferred cation form of the zeolite catalyst is that in which the ion-exchange capacity is about 50-60 percent occupied by polyvalent metals such as Group II-A, Group II-B and rare earth metals, and 5 to 30 percent of the cation sites are either decationized or occupied by hydrogen cations.
For alkylation and dealkylation processes the polyvalent metal cation form of the zeolite catalyst is preferred with less than 10 equivalent percent of the cations being alkali metal. When employed for dealkylation of alkyl aromatics, the temperature is usually at least 350F and ranges up to a temperature at which substantial cracking of the feedstock or con~ersion products occurs, generally up to about 700F, The temperature is preferably at least 450F and not greater than the critical tempera-ture of the compound undergoing dealkylation. Pressure contitions are applied to retain at least the aromatic feed in the liquid state. For alkylation the temperature can be as low as 250F but is preferably at least 350F. In alkylating benzene, toluene and xylene, the preferred alkylating agents are olefins such as ethylene and propy-lene.
- lOo -~ 71 ~ 3 ~ 12346-1 The hydrothermal stability of many of the zeolite compositions of this invention can be enhanced by ccnven-tional steaming procedures. In general the ammonium or hydrogen cation forms of the zeolite are contacted with steam at a water vapor pressure of at least about 0.1 psla, preferably at least 0.2 psia up to several atmospheres.
Preferably steam at one atmosphere is employed. The steaming temperatures range from 100C up to the crystal destruc-tion temperature of the zeolite, but are preferably in the range of 600C to 850C. Steaming periods of a few minutes, e.g. 10 minutes, up to several hours can be employed depend-ing upon the specific temperature conditions. The steaming also produces changes in the selectivity of the catalyst in many cases.
In the above-described catalytic conversion processes the preferred zeolite catalysts are those in which the zeolite constituent has pores of sufficient dlameter to adsorb benzene. Such zeolites include LZ-210, LZ-211, LZ-212, LZ-217 and LZ-213 Example 20 In order to evaluate the catalytic activity of LZ-210 in the catalytic cracking of a gas oil feedstock, a sample of the catalyst was prepared as follows: 990 g. (NH4)2SiF6 were dissolved with stirring $nto 3.8 liters of distilled water at 50C. The solution was put into a dropping funnel fitted on a three-necked round-bottom flask, A solution of 1500 grams of ammonium acetate in 10 liters of water was then added to the flask. Ammonium zeolite Y in the amount of 2500 grams (anhydrous weight, molar SiO2/A1203 =
4.87) was slurried up in the ammonium acetate solution at 75C. A mechanical stirred was fitted to the center hole 337 l2346-l of the flask, which was als~ fitted with the necessary thermo-couples and temperature controllers. Addition of the 3.~ liters of (NH4)2SiF6 solution in lO0 ml. incre-ments begun with a 5-minute interval between each sddition.
The initiàl pH of the slurry was measured at 5.74 and after all of the (NH4)2SiF6 solution was added to the pH
of the slurry was 5.38. The mixture was heated at 95C
with stirring for an additional 18 hours, the dropping funnel ha~ing been replaced with a condenser. The stoichio-metry of the reaction was of the order of one Si added as (NH4)2SiF6 for every two Al atoms present in the zeoli~e.
At the conclusion of the reaction the pH of the slurry was 5.62. The reaction mixture was then filtered and the solids washed with about 25 liters of hot tistilled water, until quantitative tests indicated absence of NH3 and aluminum in the effluent wash water. It was then dried 2 hours at 110C.
The product had a unit cell dimension (aO) of 24.41 A, a cation equivalence of 0,94, and the following compositional mole ratios:
Na20/A1203 e 0~ 076 (NH4)20/A1203 e 0, 862 SiO2/A1203 - 9. 87 The powdered LZ-210 was admixed with 1.5 times its weight of alumina and formed by means of extrusion into 1/16"
pellets. The pellets were calcined at 500C for 6 hours.
The resulting extrudates were sized to 60-lO0 mesh and evaluated for cracking actiivty using a gas oil feedstock, (Amoco FHC-893), in accordance with the procedure of AS~I
test No. D 032,04. The following results were obtained:
~t7~7 12346-1 AST~ Conversion 86.0 G l 35.0 Gasoline2 28.5 Coke3 8.89 H2 0.14 Cl 0.38 C2 + C2 = 1.3 C3 2.6 i-C4 6.5 n-c4 3.2 c4 = 10.8 C5 5.1 (1) weight % feed converted to gas ~2~ Gasoline - wt. product (180F-421F)/Total product (3) Weight % feed converted to coke (gravimetric) ExamPle21 A sample of LZ-210 having a SiO2/A1203 molar ratio of 9.6 and containing 0,7 weight % Na20 was loaded with 0.53 weight percent palladium and composited with sufficient alumina to form an 80% Pd/LZ-210 - 20% A1203 catalyst composition having an average bulk density of 0.48 cc./g.
This catalyst composition was tested for gasoline hydro-cracking performance using the following test conditions:
Feedstock - Gas Oil, API - 39.0, BP.R = 316-789F.
Pressure - 1450 psig.
H2/Oil c 8000 SCF/BBL.
To determine the second stage hydrogenation activity of the catalyst, the feed was doped with 5000 p?m sulfur as throphene. The activity in this regard was, in terms of the temperature required to obtain a 49.0 API product after 100 hours in stream, 498F. To determine the first stage (cracking) activity, the feed was doped with 5000 ppm sulfur as thiophene and 2000 ppm nitrogen as 5-butyla~ine.
The activity in this regard, in terms of the temperature required to obtain a 47.0 API product after 100 hours on stream, was 692F.
_ 1 nL _
Claims (65)
1. Method for inserting silicon atoms as SiO4 tetrahedra into the crystal lattice of an aluminosilicate zeolite which comprises contacting a crystalline zeolitic aluminosilicate having a SiO2/Al2O3 molar ratio of at least 3 and pore diameters of at least 3 Angstroms with a fluoro-silicate salt in an amount of at least 0.0075 moles per 100 grams of the zeolitic aluminosilicate on an anhydrous basis, said fluorosilicate salt being in the form of an aqueous solution having a pH value within the range of 3 to about 7 and brought into contact with the zeolitic aluminosilicate at a rate sufficiently slow to preserve at least 60 percent of the crystallinity of the starting zeolitic aluminosilcate.
2. Method according to claim 1 wherein the starting crystalline zeolitic aluminosilicate is at least partially in the ammonium cationic form.
3. Method according to claim 2 wherein the fluoro-cilicate salt is ammonium fluorosilicate.
4. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite Y.
5. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of mordenite.
6. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite omega.
7. Method according to claim 2 wherein the starting zeolite aluminosilicate has the essential crystal structure of zeolite Rho.
8. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite L.
9. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of zeolite W.
10. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal struc-ture of zeolite N-A.
11. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal struc-ture of offretite.
12. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal structure of clinoptilolite.
13. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal struc-ture of chabazite.
14. Method according to claim 2 wherein the starting zeolitic aluminosilicate has the essential crystal struc-ture of erionite.
15. Method according to claim 1 wherein the starting zeolitic aluminosilicate is zeolite Y having a SiO2/Al2O3 molar ratio of from 3 to 7, the reaction is carried out at a temperature of from 20 to 95°C. and the fluorosili-cate salt is employed in an amount at least as great as determined from the equation AFS = 1.395a - 0.275 wherein AFS is the minimum number of moles of fluorosili-cate salt per 100 grams of zeolite starting material on an anhydrous basis and "a" is the mole fraction of framework aluminum tetrahedra of the starting zeolite Y as represented by the expression (AlaSib?z)02 wherein Al represents frame-work aluminum tetrahedra, Si represents framework silicon tetrahedra and ? represents defect sites, "b" is the mole fraction of silicon tetrahedra and "z" is the mole fraction of framework defect sites.
16. A crystalline aluminosilicate having at least some of its original framework aluminum atoms replaced by extraneous silicon atoms and having the chemical composition [A1(a-N)Sib+(N- .DELTA.z) ?z]02 wherein Al(a-N) represents the mole fraction of aluminum tetrahedra in the product zeolite; "a" represents the mole fraction of aluminum tetrahedra in the original zeolite;
"N" represents the mole fraction of aluminum tetrahedra removed from the original zeolite, and has a value of at least 0.3a; Sib+(N-.DELTA.z) represents the mole fraction of silicon tetrahedra in the product zeolite; "b" represents the mole fraction of silicon tetrahedra in the original zeolite; (N- .DELTA.z) represents the mole fraction of silicon tetrahedra resulting from the substitution of extraneous silicon into the crystal lattice; " ? " represents frame-work defect sites; "z" represents the mole fraction of framework defect sites; " .DELTA.z" represents the difference between the mole fraction of framework defect sites of the original zeolite and the zeolite containing the extraneous silicon atoms and has a value of less than 0.08; (N- .DELTA.z)/N has a value at least as great as 0.5;
and [b+(N- .DELTA.z)]/(a-N) has a value of at least 4Ø
"N" represents the mole fraction of aluminum tetrahedra removed from the original zeolite, and has a value of at least 0.3a; Sib+(N-.DELTA.z) represents the mole fraction of silicon tetrahedra in the product zeolite; "b" represents the mole fraction of silicon tetrahedra in the original zeolite; (N- .DELTA.z) represents the mole fraction of silicon tetrahedra resulting from the substitution of extraneous silicon into the crystal lattice; " ? " represents frame-work defect sites; "z" represents the mole fraction of framework defect sites; " .DELTA.z" represents the difference between the mole fraction of framework defect sites of the original zeolite and the zeolite containing the extraneous silicon atoms and has a value of less than 0.08; (N- .DELTA.z)/N has a value at least as great as 0.5;
and [b+(N- .DELTA.z)]/(a-N) has a value of at least 4Ø
17. Composition according to claim 16 wherein the value of .DELTA.z is less than 0.05.
18. Composition according to claim 16 wherein said zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al of from 0.85 to 1.1 and having an X-ray powder diffraction pattern containing at least the d-spacings set forth in Table A.
19. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table C, and wherein the value of is at least 7.5.
20. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table D, and wherein the value of is at least 4.
21. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, and wherein the value of is at least 4.
22. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed is a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table F, and wherein the value of is at least 4,
23. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table G, and wherein the value of is at least 4.
24. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table H, and wherein the value of is at least 4.
25. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation psecies, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table 1, and wherein the value of is at least 4.
26. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table J, and wherein the value 0 is at least 5.5.
27. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table K, and wherein the value of is at least 4.
28. Composition according to claim 16 wherein the zeolitic aluminosilicate has a cation equivalent expressed as a monovalent cation species, M+/Al, of 0.9 ? 0.1 and an X-ray powder diffraction pattern having at least the d-spacings set forth in Table L, and wherein the value of is greater than 10.
29. Zeolitic aluminosilicate having a cubic crystalline structure and which in the dehydrated state composition expressed in terms of mole ratios of oxides (0.85 - 1.1)M2/n0 : Al2O3 : x SiO2 wherein M is a cation having a valence of "n" and "x"
has a value greater than 8, having an X-ray powder diffraction pattern having at least the d-spacings of Table A and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
has a value greater than 8, having an X-ray powder diffraction pattern having at least the d-spacings of Table A and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
30. Composition according to claim 29 wherein "x"
has a value of from 9 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10.000A3.
has a value of from 9 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10.000A3.
31. Zeolitic aluminosilicate having in the dehydrated state a chemical composition expressed in terms of mole ratios of oxides (0.9 ? 0.1) M2/nO : Al2O3 : x SiO2 wherein "M" is an inorganic cation having the valence "n", x is a value greater than 15, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table B, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
32. Composition according to claim 31 wherein "x"
has a value of from 17 to 120 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
has a value of from 17 to 120 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
33. Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein "M" is a cation having the valence "n" and "x"
is a value greater than 7, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table D, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
is a value greater than 7, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table D, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
34. Composition according to claim 33 wherein "x"
has a value of from 8-120 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
has a value of from 8-120 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
35. Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 ? 0.1 M2/nO : Al2O3 : X SiO2 wherein "M" is a cation having the valence "n" and "x"
is a value greater than 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
is a value greater than 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table E, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
36. Composition according to claim 36 wherein the value of "x" is from 8 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000 A3.
37. Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 ? 0.1 M2/nO : A12O3 : x SiO2 wherein "M" is a cation having the valence "n" and "x" is a value greater than 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table F, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
38. Composition according to claim 37 wherein "x"
has a value of from 10 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000 A3.
has a value of from 10 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000 A3.
39. Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 ? 0.1 M2/nO : Al2O3 : X SiO2 wherein "M" is a cation having the valence "n" and "x"
is a value greater than 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table G, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
is a value greater than 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table G, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
40. Composition according to claim 39 wherein "x"
has a value of from 8 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000 A3.
has a value of from 8 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000 A3.
41. Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides:
0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x"
has a value of at least 8 an X-ray powder diffraction pattern having at least the d-spacings set forth in Table H, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x"
has a value of at least 8 an X-ray powder diffraction pattern having at least the d-spacings set forth in Table H, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
42. Composition according to claim 41 wherein the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000 A3.
43. Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides:
0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x" has a value of greater than 8 an X-ray powder diffraction pattern having at least the d-spacings set forth in Table I, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x" has a value of greater than 8 an X-ray powder diffraction pattern having at least the d-spacings set forth in Table I, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
44. Composition according to claim 43 wherein "x"
has a value of from 8 to 20 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
has a value of from 8 to 20 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
45. Zeolitic aluminosilicate composition having in the dehydrated state a chemical composition expressed in terms of mole ratios of oxides:
0.9 ? 0.1 M2/nO: Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x" has a value of greater than 11 an X-ray powder diffraction pattern having at least the d-spacings set forth in Table J, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
0.9 ? 0.1 M2/nO: Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x" has a value of greater than 11 an X-ray powder diffraction pattern having at least the d-spacings set forth in Table J, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
46. Composition according to claim 45 wherein "x" has a value of from 12-20 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
47. Zeolitic aluminosilicate composition having in the dehydrated state a chemical composition expressed in terms of mole ratios of oxides:
0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x"
has a value of at least 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table K, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein M is a cation having the valence "n" and "x"
has a value of at least 8, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table K, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
48. Composition according to claim 47 wherein "x" has a value of from 8 to 20 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
49. Zeolitic aluminosilicate composition having in the dehydrated state, a chemical composition expressed in terms of mole ratios of oxides 0.9 ? 0.1 M2/nO : Al2O3 : x SiO2 wherein M is a cation having a valence "n" and "x" is a value greater than 20, an X-ray powder diffraction pattern having at least the d-spacings set forth in Table L, below, and having extraneous silicon atoms in its crystal lattice in the form of framework SiO4 tetrahedra.
50. Composition according to claim 49 wherein "x" has a value of from 22 to 60 and the extraneous silicon atoms are present in an amount of at least 1.0 per 10,000A3.
51. Process for hydrocarbon conversion which comprises contacting a hydrocarbon under converting conditions with a crystalline zeolitic aluminosilicate of claim 16.
52. Process according to claim 51 wherein the hydro-carbon conversion process is catalytic cracking.
53. Process according to claim 51 wherein the hydro-carbon conversion process is hydrocarcking.
54. Process according to claim 51 wherein the hydro-carbon conversion process is alkylation.
55. Process according to claim 51 wherein the hydro-carbon conversion process is isomerization.
56. Process according to claim 51 wherein the hydrocarbon conversion process is hydrofining.
57. Process according to claim 51 wherein the hydro-carbon conversion process is reforming.
58. Process for hydrocarbon conversion which comprises contacting a hydrocarbon under converting conditions with a crystalline zeolitic aluminosilicate of claim 29.
59. Process for hydrocarbon conversion which comprises contacting a hydrocarbon under converting conditions with a crystalline zeolitic aluminosilicate of claim 31.
60. Process for hydrocarbon conversion which comprises contacting a hydrocarbon under converting conditions with a crystalline zeolitic aluminosilicate of claim 41.
61. Process according to claim 60 wherein the hydro-carbon conversion process is hydrocracking.
62. Process according to claim 60 wherein the hydro-carbon conversion process is catalytic cracking.
63. Process according to claim 60 wherein the hydro-carbon conversion process is alkylation.
64. Process according to claim 60 wherein the hydro-carbon conversion process is catalytic dewaxing.
65. Process according to claim 60 wherein the hydro-carbon conversion process is xylene isomerization.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000392137A CA1171837A (en) | 1981-12-11 | 1981-12-11 | Silicon substituted zeolite compositions and process for preparing same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000392137A CA1171837A (en) | 1981-12-11 | 1981-12-11 | Silicon substituted zeolite compositions and process for preparing same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1171837A true CA1171837A (en) | 1984-07-31 |
Family
ID=4121610
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000392137A Expired CA1171837A (en) | 1981-12-11 | 1981-12-11 | Silicon substituted zeolite compositions and process for preparing same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1171837A (en) |
-
1981
- 1981-12-11 CA CA000392137A patent/CA1171837A/en not_active Expired
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