DE3215841A1 - CRYSTALLINE SILICATE PARTICLES, METHOD FOR THEIR PRODUCTION AND THEIR USE - Google Patents

Description

- 5 description

The invention relates to crystalline silicate zeolites, their synthesis and hydrocarbon conversion processes using these materials. In particular, the invention is concerned with synthesis and uses of crystalline silicates with an outer shell that contains aluminum, but this shell the same X-ray diffraction pattern and crystal structure as the core of the crystalline silicate exhibits.

Some of these materials and their synthesis are known. In US-RE 29 948 organosilicates are with ZSM-5 structure described. U.S. Patent 4,061,724 describes silicalite. Bibby et al. is described in "Nature", Volume 28 on pages 664 - 665 (23 August 1979) "Silicalite-2" described. The aluminosilicate zeolites ZSM-5 and ZSM-11 are described in U.S. Patents 3,702,886 and 3,709,979.

Due to their ordered porous structure, which creates interconnected cavities, the crystalline silicates and the ZSM zeolites are selective towards certain molecules. This means, that the pores are able to adsorb molecules of certain dimensions, while those with larger dimensions be repelled. It was not previously known to increase the selectivity by significantly increasing the surface area of crystalline Silxkatkrxstallxsatoren with an outer isocrystalline layer of an aluminum-containing > Zeolite is activated. There are some references which explain the inactivation of the surface

of aluminosilicates in such a way that an isocrystalline outer shell of an aluminum-free material is applied (see US Pat. Nos. 4,088,605, 4,148,713 and 4,203,869).
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The invention provides particles made up of an inner section and an outer Section, which is provided as a shell around the inner section, exist, the outer section the has the same crystal structure as the inner portion and the inner portion is made of a crystalline Silicate with a medium pore size, which is essentially free of aluminum, while the outer Has section aluminum oxide.

The invention also relates to a hydrocarbon conversion process, which consists of a hydrocarbonaceous feedstock with particles from an inner section and an outer section, which is arranged as a shell around the inner section, wherein the outer portion has the same crystal structure as the inner portion and the inner portion consists of a crystalline silicate with a medium pore size that is essentially free of aluminum is to be contacted under hydrocarbon conversion conditions while the outer portion contains alumina.

The crystalline silicates suitable according to the invention are essentially aluminum-free materials with medium pore size and can use the silicic acid analogues of medium pore size zeolites such as ZSM-5 and ZSM-11. Despite their low aluminum content the crystalline silicates are suitable for cracking and

Hydrocracking and are particularly valuable for carrying out catalytic high pressure dewaxing processes for the recovery of olefins, also for carrying out olefin polymerization reactions and for carrying out
other petroleum refining processes.

Although they have unusually low aluminum contents, ie, show high silica: alumina ratios, they are very active even when the silica: alumina ratio exceeds 1000: 1. The activity is surprising because the catalytic activity is generally the network of aluminum atoms and cations associated with these aluminum atoms
are assigned. These materials keep theirs

Crystallinity for long periods of time even in the presence of water vapor at high temperature, ie conditions that cause irreversible breakdown of the
Induce lattices of many zeolites, for example des
X and A types. Carbonaceous deposits can

be removed by burning at temperatures higher than those normally used to restore activity. In many
These crystalline silicates show a very strong environment
low tendency to form coke, a property that makes these materials suitable for very long periods of operation between burn-off regeneration cycles.

The term "mean pore size" is to be understood as meaning an effective pore opening between approximately 5.0 and 6.5 Å when the crystalline silicate is in the Η form. Silicates with pore openings within this area
tend to have unique molecular sieve properties. in the
In contrast to small-pore zeolites such as erionite,

they allow the entry of hydrocarbons with certain Branches into the zeolite voids. In contrast to large-pore zeolites, such as the faujasites, are capable they between n-alkanes and slightly branched alkanes on the one hand and larger branched alkanes with for example to distinguish quaternary carbon atoms.

The effective pore size can be determined using standard adsorption techniques as well as hydrocarbon-containing compounds with known minimum kinetic diameters be measured. In this context, reference is made to Breck "Zeolite Molecular Sieves", 1974 (in particular Chapter 8) and Anderson et al. See "J. Catalysis" 58, 114 (1979).

Crystalline silicates with medium pore sizes in the Η-shape typically allow the access of Molecules with kinetic diameters of 5 to 6 Ä 0 with little hindrance. Examples of such Compounds (and their kinetic diameters in Ä) are as follows: n-hexane (4,3), 3-methylpentane (5,5), Benzene (5.85) and toluene (5.8). Compounds with kinetic diameters of approximately 6 to 6.5 Å can get into the pores depending on the respective silicate, but do not enter as quickly and are effectively excluded in some cases. Connections with kinetic diameters in that The ranges from 6 to 6.5 Å are as follows: cyclohexane (6.0), 2,3-dimethylbutane (6.1), 2,2-dimethylbutane (6.2), n-xylene (6.1) and 1,2,3,4-tetramethylbenzene (6.4). in the In general, compounds with kinetic diameters of more than approximately 6.5 Å cannot enter the pore openings penetrate and therefore cannot get inside

of the crystalline silicate are adsorbed. Examples of such larger compounds are o-xylene (6.8), hexamethylbenzene (7.1), 1,3,5-trimethylbenzene (7.5) and tributylamine (8.1).
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The preferred effective pore size range is between about 5.3 and about 6.2 A. Silicalite falls for example in this area. The preferred crystalline silicates show the X-ray diffraction patterns of ZSM-5 or ZSM-11 or either of these two materials.

Standard methods are used to carry out adsorption measurements to determine the pore size. It is expedient to consider a particular molecule to be excluded if it does not reach at least 95% of its equilibrium adsorption value on the zeolite in less than approximately 10 min (p / po = 0.5; 25 ^° C.).

The mentioned ratio silicon dioxide: aluminum oxide can be determined using conventional analysis methods. This ratio represents as broadly as possible the ratio (on a molar basis) of silica to alumina in the rigid anionic Lattice of the silicate crystal, with aluminum in the binder or in a cationic or other form within the channels is excluded. Albeit crystalline silicates with a silicon dioxide: aluminum oxide ratio of at least 200: 1 are suitable, it is nevertheless preferable to use crystalline silicates with higher Use ratios of at least about 500: 1 and in particular 1000: 1. Achieve such materials after activation an intracrystalline sorption capacity for normal hexane, which at low

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relative pressures is greater than for water.

As mentioned above, crystalline silicates which are used to carry out the process according to the invention are mentioned in various literature references. "SiIikalit" (US Pat. No. 4,061,724) has, in synthesized form, a specific weight at 25 ° C. of 1.99 ± 0.05 g / cm ³ , measured by displacement of water. In calcined form (600 ⁰ C in air for 1 h) has silicalite has a specific gravity of 1.70 + _ 0.05 g / cm ^3. The average refractive indices of silicalite crystals, obtained by measuring the synthesized and the calcined form (600 ⁰ C in air for 1 h) are 1.48 + 0.01 and 1.39 _ + _ 0.01,

The Rontgenpulvermuster of silicalite (600 ⁰ C calcination in air for 1 hour) has as its six strongest lines (ie, interplanar spacings) those which are summarized in Table A ( "S" = strong and "VS" = very strong) .

there 0. 2 Table A. intensity ± 0. 2 Pelative VS 11.1 + 0. 07 VS 10.0 ± 0. 07 VS 3.85 + 0. 05 S. 3.82 ± 0. 05 S. 3.76 + S. 3.72

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■ 321584T

The following Table B lists the values which show the X-ray powder diffraction pattern of a typical silicalite composition containing 51.9 moles of SiO ₂ per mole of (TPA) ₂ O, prepared according to the method of US Pat. No. 4,061,724 and calcined in air 600 ^° C. for 1 h.

Tabel B. there Relative intensity there Relative intensity 4.35 5 11.1 100 4.25 7th 10.02 • 64 4.08 3 9.73 16 4.00 3 8.99 1 3.85 59 8.04 0.5 3.82 32 7.42 1 3.74 24 7.06 0.5 3.71 27 6.68 5 3.64 12th 6.35 9 3.59 0.5 5.98 14th 3.48 3 5.70 • 7 3.44 5 5.57 8th 3.34 11th 5.36 2 3.30 7th 5.11 2 3.25 3 5.01 4th 3.17 0.5 4.98 5 3.13 0.5 4.86 0.5 3.05 5 4.60 3 2.9C 10 4.44 0.5

Silicalite crystals in both the synthesized and the in the calcined form are orthorhombic and have the following unit parameters: a = 20.05 A, b = 19.86 A, b = 13.36 A with an accuracy of + 0.1 A. with each de.r values.

The pore diameter of silicalite is approximately 6 units and the pore volume 0.18 g / cm ³ , determined by absorption. Silicalite adsorbs neopentane (kinetic diameter 6.2 A) slowly at ambient temperature. The uniform pore structure gives the mass size-selective molecular sieve properties, the pore size allowing the separation of p-xylene from o-xylene and ethylbenzene and the separation of compounds with quaternary carbon atoms from those with carbon-carbon bonds of lesser value.

The crystalline silicates of US-RE 2 9 948 are with the following composition given in an anhydrous state:

0.9 + _ 0.2 / ScR ₂ O + (1-x) M _{2 / n} q /: <0.005 Al ₃ O ₃ :> 1SiO ₂

where M is a metal with the exception of a metal from groups HIA, η denotes the valence of the metal, R represents exnene-alkylammonium radical, χ is a number which is greater than O but does not exceed 1, the organosilicate being characterized by the X-ray diffraction pattern from Table C. is.
25th

5841

- 13 Table C Interplanar distance d (A) Relative intensity

11.1 p

10.0 S.

7.4 W.

7.1 W

6.3 W

6.4,
5.97)

5.56 W 5.01 '- W.

4.60 W

4.25 W

3.85 VS

3.71 S

3.04 W.

2.99 W

2.94 W.

The crystalline silicate polymorph of US Pat. No. 4,073 is given with a specific gravity of 1/70 ± 0.05 g / cm ³ and an average refractive index of 1.39 ± 0.01 after calcination in air at 600 ^° C. , this material being made by a hydrothermal process, when carried out, fluoride anions are added to the reaction mixture. The crystals, which can be up to 200 microns in size, show essentially no infrared adsorption in the hydroxyl stretching region and are organophilic. They show the X-ray diffraction pattern from Table D.

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Table D. intensity there) 91 11.14 100 10.01 · 17th 9.75 1 8.99 0.5 8.04 0.5 7.44 0.2 7.08 4th 6.69 6th 6.36 10 5.99 5 5.71 5 5.57 1 5.37 1 5.33 0.3 5.21 1.5 5.12 3 5.02 6th 4.97 0.6 4.92 0.5 4.72 2 4.62 0.6 4.47 3 4.36 4th 4.25 0.5 4.13 1.5 4.08 3 4.00 44 3.8 5 25th 3.82 21 3.71 5 3.65 5 3.62

- ic «,

Table D (continued) d (A) Intensity

3.59 1

3.48 ι, 5

3.45-3

3.44 3

3.35 3

3.31 x 5

3.25 1.5

3.23 p, 8

'3.22 0.5

The literature describes the following method for the production of crystalline silicate, namely "Silicalite-2" (Nature, August 1979) as follows:

The Silicalite-2 precursor is made using only tetra-n-butylammonium hydroxide, although addition of ammonium hydroxide or hydrazine hydrate as a source of extra hydroxyl ions increases the rate of the reaction considerably. A successful fabrication technique is to mix 8.5 mol SiO- as silica (74% SIO ₂₎ 1.0 mol of tetra-n-butylammonium hydroxide, 3.0 moles of NH ₄ OH and 100 moles of water in a steel bomb at 170 and ⁰ C to be heated for 3 days.

The production of crystalline silicates generally consists of hydrothermal crystallization a reaction mixture of water, a silicon dioxide source and an organic "template compound" (templating compound) at a pH of 10 to 14. Representative template components are quaternary cations,

such as XR ₄ / where X is phosphorus or nitrogen, while R is an alkyl radical containing 2 to 6 carbon atoms, for example tetrapropylammonium hydroxide or halide.
5

When the organic stencil compound is added to the system in the hydroxide form in an amount appropriate to it suffices to set a basicity equivalent for a pH of 10 to 14, then the reaction mixture needs contain only water and a reactive form of silica as additional ingredients. In the cases in which the pH must be increased to about 10, ammonium hydroxide or alkali metal hydroxides can be used suitably used for this purpose, in particular the hydroxides come from lithium, sodium. or potassium in question. It has been found that no more than 6.5 moles of alkali metal oxide per mole of alkylonium compound is necessary for this purpose, even if none of the alkylonium compounds are in the form of theirs 0 hydroxide is present.

The specific crystalline silicates described are catalytically inactive when manufactured in the presence of organic cations, possibly as a result of the intracrystalline free space being taken up by organic cations from the manufacturing solution. However, the silicates can be activated (1000 ⁰ F) in air by heating in an inert atmosphere at 540 ⁰ C (1000 ⁰ F) for 1 h and subsequent base exchange with ammonium salts, as well as a further calcination bei54O ⁰ C.

The silicates can either be in the alkali metal form, for example in the sodium form, the ammonium form, the hydrogen form or in another single equivalent or

multiple equivalent cationic form can be used. Preferably one or the other of the latter two forms is used. They can also be used in intimate combination with a hydrogenation component, such as tungsten, vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese or a noble metal such as platinum or palladium, can be used when a hydrogenation-dehydrogenation function is to be performed. Such a one Component can be intimately incorporated into the mass by exchange, by impregnation or by physical Mixing are introduced. Such a component can be in or on the present catalyst as such are impregnated, for example in the case of platinum by treating the zeolite with a platinum metal-containing Ion. Suitable platinum compounds are chloroplatinic acid, platinum (II) chloride and various Compounds containing the platinum-amine complex.

The compounds of suitable platinum or other metals can be divided into compounds in which the metal is present in the cation of the compound as well as compounds in which it is present in the anion of the compound. Either type containing the metal in the ionic state can be used. A solution in which platinum metals are present in the form of a cation or a cationic complex, for example Pt (NH ₃ ) gCl-, is particularly suitable. For some hydrocarbon conversion processes, this noble metal form of the catalyst is unnecessary, for example for isomerizing o-xylene in the liquid phase at a low temperature.

«* Β α

• ΚΙ to tf

^: * Τ ' ^: .Λ ::. 32: ί5841

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Regardless of whether it is used as an adsorbent or as a catalyst in one of the processes mentioned above, the catalyst should be at least partially dehydrated. This can by heating to a temperature between 200 and 600 ⁰ C in an atmosphere such as air, nitrogen, etc., and h take place at atmospheric pressure or sub-atmospheric pressure during äiner time between 1 to 48th Dehydration can also be carried out at lower temperatures merely in such a way that the catalyst is placed in a vacuum, but a longer time is required in order to achieve a sufficient degree of dehydration.

In accordance with a preferred feature of the invention, the catalysts are selected such that they have a crystal lattice density ^{in the dry hydrogen form of not substantially below about 1.6 g per cm 3.} The dry density for known structures can be calculated from the number of silicon plus aluminum atoms per 1000 cubic A, for example using the method given on page 19 of the article relating to the zeolite structure by WM Meir. This work is published in full in Proceedings of the Conference on Molecular Sieves, London, April 1967, published by the Society of Chemical Industry, London, 1968. If the crystal structure is unknown, the crystal lattice density can be determined using classic pycnometer methods. For example, it can be determined by immersing the dry hydrogen form of the zeolite in an organic solvent that is not sorbed by the crystal. It is possible that the unusually long-lasting activity and stability of this class of zeolites with their high anionic properties

Crystal lattice density of not less than about 1.6 g / cm ³ . This high density must of course be combined with a relatively small amount of free space within the crystal, which should result in the more stable structures. However, this free space is important as a site for catalytic activity.

After completion of the synthesis of the crystalline silicate it is essential for the purposes of the invention to reduce the nucleation of the new silicate crystals or eliminate while at the same time keeping crystal growth high. To the outer aluminum-containing To produce a shell, it is also essential that a reactive aluminum is added to the reaction mixture will.

It is therefore necessary to further process the silicate and add mixture a enthaltonde Aluminlum-to crystallization of SiO ₉ to effect and Al ₉ O-, on the surface of the silicate, the ₂₂₃ mixture has the same crystal structure as the core silicate. This can be done by completely replacing the reaction mixture or by adding an aluminum-containing solution to the original reaction mixture.

Typical reaction conditions provide for the mixture to be heated to a temperature of approximately 80 to approximately 200 ^° C. for a period of approximately 4 hours to approximately 30 days. As in the case of the general ATuminosilicate synthesis, the digestion of the gel particles is carried out until the crystalline aluminosilicate layer is completely as an outer shell on the critical

has formed stable particles. The product crystals are then separated, for example by cooling and filtering, gewaöchen with water and in about 80 to about 15O ⁰ C dried. 5

The most effective production method consists in the formation of the crystalline silicate, followed by the crystalline Silicate particles are used as inoculants in the reaction mixtures that are normally used for preparation of medium pore size zeolites can be used. Either the pH of the reaction mixture or the temperature can be used to control and minimize the nucleation of discrete zeolite particles will. Lower pH values, for example from 9 to 10, reduce the silica solubility, whereby decreases the number of nucleation sites and causes aluminosilicate deposition on the nucleators will. Lower temperatures slow down the rate of crystal formation and nucleation, 0 so that an aluminosilicate deposition is effected on the nucleating agents or the seed material. At deeper pH values of for example 9 to 10 can be a normal temperature range for hydrothermal crystallization be respected. Preferably the temperature is between about 100 and 120 ° C and the pH set to about 10-12. Under these conditions the nucleation of the zeolite is kept to a minimum while the aluminosilicate layer is removed forms on the exterior of the silicate nucleation materials. The vaccination methods as described in U.S. Patent 4,175 and a mixture of alcohol and ammonium hydroxide instead of tetrapropylammonium cations can also be used. Using these methods, it is preferable to

adjust the pH to 1O to 14 and the temperature to about 120 to 160 ⁰ C. In general are. the organic cation / SiO molar ratio and the hydroxide content of the mixture from which the crystalline silicate is produced are higher than in the mixture in which the isostructural aluminum oxide-containing layer is crystallized on the silicate.

The original cations used in the invention Materials present can be replaced with a variety of other cations according to known methods will. Typical substitute cations are hydrogen, ammonium and metal cations, mixtures also being possible come. Of the substitute metal catalysts, the cations of metals such as the rare earth metals, Manganese and cadmium, as well as the metals of Group II of the Periodic Table of the Elements, such as Zinc, and metals from Group VIII of the Periodic Table of the Elements, such as nickel, are preferred. Typical ion exchange methods are contacting members of the zeolite family with a salt of the desired replacement cation or cations. Albeit a wide variety of salts are used can be, the chlorides, nitrates and sulfates are nevertheless preferred.

Representative ion exchange methods are taught, for example, in U.S. Patents 3,140,249, 3,140,251, and 3,140,253 described.

Following contact with the salt solution of the desired replacing cation, the materials are preferably washed with water and dried at a temperature of between 65 and about 320 ⁰ C (150 to 600 ⁰ P) and then in air or other inert gas

calcined at temperatures between about 260 ⁰ C and about 650 ⁰ C (500 and 1200 ⁰ F) for periods of 1 to 48 hours or more.

Regardless of the cations that replace the sodium in the synthesized form, the catalyst remains the spatial arrangement of the aluminum, silicon and oxygen atoms that make up the basic crystal lattice in one given zeolite form according to the present invention, essentially by the described replacement of the Sodium or another alkali metal unchanged, as shown by an X-ray powder diffraction pattern of the ion-exchanged material results. For example, the silicate / aluminosilicate structure of FIG ZSM-5 has the same X-ray diffraction pattern as shown in Table C above is.

The materials according to the invention become masses with Manufactured in a variety of shapes and sizes. In general, the particles can be in the form of a powder, a granulate or a shaped product are present, for example in the form of an extrudate with a Particle size sufficient to pass through a two-mesh sieve (Tyler) Mnd on a 400 mesh sieve (Tyler) lagging behind. In those cases where the catalyst is shaped, for example by Extrusion, the crystalline silicate / aluminosilicate can be extruded or dried or partially before drying dried and then extruded.

In the case of many zeolites, it is advantageous to use the crystalline silicates / aluminosilicates

to add other materials that are against the temperatures and conditions are stable, as they are observed in organic conversion processes. Such materials are active as well as inactive materials as well as synthetic or naturally occurring materials Zeolites, for example inorganic materials such as clays, aluminum oxide, silicon dioxide and / or metal oxides. The latter can either occur naturally or in the form of gelatinous precipitates or Gels are present and consist, for example, of mixtures of silicon dioxide and metal oxides. The usage of a material in connection with the invention Catalysts cause an improvement in the conversion and / or the selectivity of the catalyst in carrying out certain organic conversion processes. Inactive materials serve in appropriate Way as a diluent to control sales in a given process, making products more economical Manner can be obtained without using other methods of controlling the reaction rate must be applied. Usually zeolite materials were found in naturally occurring Clays, such as bentonite or kaolin, to: improve the crush resistance of the catalyst among the technical Confined working conditions. These materials, i.e. H. Clays, oxides, etc., serve as binders for the Catalyst. It is useful to have a catalyst with good crush resistance because the catalyst in an oil refinery is often one is subjected to raw handling by which the catalyst is crushed into a powder-like material which can pose processing problems. These clay binders were used to improve the crush strength of the catalyst.

Naturally occurring clays that can be mixed with the crystalline silicate / aluminosilicate are for example, clays of the montmorillonite and kaolin families, these families including sub-bentonites. In addition, the kaolins conventionally called Dixie McNamee-Georgia and Floridatone come into question are known, as well as other clays in which the main mineral component of halloysite, kaolinite, Consists of dickite, nacrite or anauxite. Such clays can be obtained in the raw state as originally obtained have been used, they can also first of a calcination, an acid treatment or be subjected to chemical modification.

In addition to the materials specified above, the materials of the invention can with a porous matrix material, such as silicon dioxide / aluminum oxide, silicon dioxide / magnesium oxide, silicon dioxide / Zirconium oxide, silicon dioxide / thorium oxide, silicon dioxide / Beryllium oxide, silicon dioxide / titanium oxide and with ternary masses, such as silicon dioxide / aluminum oxide / thorium oxide, Silica / alumina / zirconia, silica / alumina / magnesia or silicon dioxide / magnesium oxide / zirconium oxide. The matrix can be in the form of a cogel. The relative Amounts of the finely divided crystalline aluminosilicate, which the aluminum-rich outer shell and the inorganic oxide gel matrix contains, can significantly with the content of crystalline aluminosilicate vary, the content can vary from about 1 to about 90 wt .-%. Especially if that If mixed material is produced in the form of spheres, the content can be between about 2 and about 50% by weight, based on the mixed material, vary.

For the most catalytic! Purposes it is preferable that the crystalline silicate is free of basic materials that neutralize its active Bodies tend. The common basic materials found in zeolites are alkali metals, especially sodium used in the hydrothermal reaction mixture. For most of the known ones Applications which are carried out using acidic zeolites, the alkali metal content is preferably below 0.1% by weight and in particular below 0.03 and very particularly preferably below about 0.01 wt%. For a few unusual non-acidic processes, for example for education of benzene from C ~ alkanes, for which a zeolite is required that is essentially free of acidity, the alkali metal content is preferably high.

Using a catalyst of the invention containing a Hydrierungskomponeiite, heavy petroleum stocks, cycle stocks, and other hydrocrackbare materials at temperatures between 200 and 450 ⁰ C can be hydrocracked (400 and 850 ⁰ F) molar in compliance ratios of hydrogen to hydrocarbon feedstock between 2 and 80 . The pressure varies between 0.7 and 175 bar (10 to 2500 psig) while the liquid space velocity varies between 0.1 and 10.

The crystalline silicate / aluminosilicates of the present invention can be used for catalytic dewaxing can be used either in the presence or absence of hydrogen and at high or low pressures . Catalytic particles containing these materials can also be used to stabilize hydrocracked Schmiejrölen versus photolytisehen

Oxidation can be used.

Using the catalyst of the invention for a catalytic cracking hydrocarbon cracking feedstocks can be cracked at contact times of 0.1 to 10 S / a temperature between about 290 and 700 ° C (550 and 1300 ⁰ F) and at a pressure between about atmospheric pressure and 100 atmospheres.

Using a catalytically active form of a zeolite according to the invention which contains a hydrogenation component, reforming starting materials can be reformed while maintaining a temperature between 370 and 540 ^° C. (700 and 1000 ^° F). The pressure can be between 7 and 70 bar, but preferably fluctuates between 14 and 49 bar. The liquid space velocity is generally between 0.1 and 10 and preferably between 0.5 and 4 and the hydrogen: hydrocarbon molar ratio is generally between 1 and 20 and preferably between 4 and 12.

The catalyst can also be used for the hydroisomerization of normal paraffins if it is provided with a hydrogenation component such as platinum. The hydroisomerization is carried out at a temperature between 90 and 370 ⁰ C and preferably 150 and 290 ⁰ C at a liquid space velocity between 0.1 and 2 and preferably between 0.25 and 0.50 and using hydrogen in such an amount that the hydrogen: hydrocarbon molar ratio is between 1: 1 and 5: 1. Further, the catalyst can be used for Olefinxsomerisationsverfahren, temperatures 1-260 ⁰ C are observed.

The catalysts of the invention are particularly suitable for carrying out olefin polymerization reactions, in which the crystalline core silicate has lower alkyl olefins / such as propene and butene, for longer, polymerized straight-chain or slightly branched olefins, while the outer and more active aluminosilicate shell the further polymerization of the lower alkyl olefins with the longer chains caused by the Core can be generated, can catalyze. The result is larger and multi-branched long chain olefins. Due to the controllable depth of the outer shell, both long and branched chain can be used Olefins are polymerized without them being completely in the pore structure to achieve the catalytic Bodies fit. Furthermore, the aluminosilicates produced are relatively large and easy to manufacture and filter. Since most of the acidic spots are near the outer surface, zeolites accelerate Reactions that are limited by diffusion, such as the polymerization of large olefins.

example

A crystalline silicate according to the present invention is produced by the following method: 2.3 g of NaNO _{3 are dissolved} in 10 ml of H ₂ O. Then 100 g of a 25% strength tetrapropylammonium hydroxide solution are placed in a polyethylene beaker and the NaNO ^ solution is added with rapid stirring. 40 g of Ludox AS-30 (30% strength silicon dioxide) are added with stirring. Then 60 g of crystalline silicate seed material, prepared according to US Pat. No. 4,061,724, are added, followed by the addition of a solution of 2.1 g of Al (NO ₃ ) ₃ .9H ₂ O in 10 ml of water. The pH is increased to 12.0 with

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concentrated HCl adjusted. The Reaktionsmischüng is poured into a Teflon bottle and placed in a stainless steel autoclave, whereupon the autoclave is maintained for 10 days at 100 ⁰ C. The autoclave is cooled and the bottle is removed. The product is filtered and washed with water and ^{dried overnight in a vacuum oven at 120 °} C. under a nitrogen pressure of 250 mm. It is then ^{calcined at 450 °} C. for 8 hours. The product particles have a crystalline silicate core with a silica: alumina molar ratio of more than 200: 1 / which is surrounded by an alumina-containing outer shell with a silica: alumina molar ratio of less than 100: 1. The crystal lattice structure of the particles is uniform.

Claims (18)

MÜLLER-BOIl £ 'mVfElV S CHÖK. HERTEl3 215841 PATENTANWiME ETXHOPBAN PATENT ATTOHNEYS DR. WOLFGANG MÜLLER-BORE (PATENT AGENT FROM 1927 - 1975) DR. PAUL DEUFEL. DIPL.-CHEM. DR. ALFRED SCHÖN. DIPL.-CHEM. WERNER HERTEL. DIPL.-PHVS. C 3356 S / sm Chevron Research Company, 525 Market Street, San Francisco, Calif. 94105 USA Crystalline silicate particles, process for their preparation and their use claims 1. Particles of an inner section and an outer section, which is arranged as a shell around the inner section, wherein the outer section has the same crystal structure as the inner section and
the inner section made of a crystalline silicate
with medium pore size, which is essentially
is free of aluminum, and the outer section
Contains aluminum oxide.
> ■ 2. Particle according to claim 1, characterized in that it has the X-ray diffraction pattern of ZSM-5. 3. Particles according to claim 1, characterized in that it has the X-ray diffraction pattern of ZSM-11. 4. A method for producing particles according to claim 1, characterized in that (1) Crystallization in a crystallization medium that is essentially free of aluminum is initiated to obtain a crystalline silicate with a medium pore size, (2) a source of aluminum is added to the crystallization medium and (3) The isostructural outer section of aluminum oxide crystallizes onto the crystalline silicate will. 5. The method according to claim 4, characterized in that the reaction mixture used sources for contains organic cations, silicon dioxide and hydroxide ions. 6. The method according to claim 5, characterized in that that the source of hydroxide ions used consists of sodium hydroxide. 7. The method according to claim 5, characterized in that in step (2) the molar ratio of organic ions to SiO ₂ compared to that in step (1) is reduced. * m · ψ 8. The method according to claim 6, characterized / that when carrying out stage (2) the hydroxide content is set lower than in stage (1). 9. The method according to claim 4, characterized in that the step (2) at a temperature of approximately 100 to 120 ⁰ C and at a pH of 10 to 12 is carried out. 10. The method of claim A _t characterized in that the crystalline silicate is a silicate having a silica: alumina molar ratio greater than about 200: 1 and the isostructural outer portion has a silica: alumina molar ratio less than about 100: 1 . 11. A method for producing particles according to claim 1, characterized in that (1) the crystalline silicate, with medium pore size is crystallized from a first reaction medium which is essentially free of aluminum, (2) removing the crystalline silicate from the first reaction medium, and (3) the crystalline silicate is added to a second reaction medium containing a source of aluminum will and (4) the isostructural alumina-containing outer layer crystallizes onto the crystalline silicate will. 12. The method according to claim 11, characterized in that the first and the second reaction mixture sources for organic cations, silicon dioxide and hydroxide ions. 13. The method according to claim 12, characterized / that the source of hydroxide ions is sodium hydroxide consists. 14. The method according to claim 12, characterized / that to carry out step (3) the molar ratio of organic ions to SiO compared to that of the study 2
fe (1) is decreased. 15. The method according to claim 13, characterized in that that a lower hydroxide content is maintained for carrying out step (3) than when carrying out the process level (1). 1.6. Process according to Claim 11, characterized in that step (3) is carried out at a temperature of approximately 100 to 120 ^° C and at a pH of 10 to 12. 17. The method according to claim 11, characterized in that the crystalline silicate used is a silicate having a silica: alumina ratio greater than about 200: 1 and is isostructural outer section a silica: alumina molar ratio less than about 100: 1. 18. Use of particles according to claims 1 to 17 for carrying out hydrocarbon conversion processes, in particular for the implementation of hydrocracking processes, catalytic cracking process, reforming process, Hydroisomerization process, olefin isomerization process, olefin polymerization process, catalytic dewaxing process as well as for the stabilization of lubricating oils.