CA1046480A - Fluid catalyst compositions - Google Patents

Abstract

FLUID CATALYST COMPOSITIONS
Abstract of the Invention Fluid catalyst particles are mixed with an inorganic colloid to improve the density and attrition resistance thereof. Typically, a fluid cracking catalyst composition containing silica-alumina hydrogel, clay and/or crystalline alumino silicates (zeolites) is mixed with an inorganic sol of silica, alumina or silica-alumina having particles of less than about 0.05 micron.

Description

-- ~L04648~

For many years commercial hydrocarbon conversion catalysts have been prepared by combining a silica-alumina hydrogel with varying amounts of clay and/or crystalline alumino silicate zeolites. In particular, large quantities of commerical cracking catalyst have been prepared in fluidized form which possess a particle size range on the order ' of 50 to 200 microns.
These fluidized catalysts are used in commercial cat cracking units wherein a high molecular weight hydrocarbon feedstock is contacted with the catalyst under conditions of high temperature and extreme attrition. During use it is ;~ found that certain quantities of commercial fluid catalysts i tend to break up and are subsequently removed from the unit during regeneration procedures. While the majority ' of the fine sized particles are removed from the stack gases .~ by the recovery systems associated with the unit, certain ~' quantities of extremely finely divided catalysts escape to !.' the atmosphere.
j~ To avoid excessive atmospheric pollution it is the `~ 20 objective of fluid catalyst manufacturers and users to increase both the attrition resistance and density of fluid , catalyst compositions and thereby decrease the amount of ;
; catalyst fines which escape recovery systems employed in `! commercial catalytic units.
It is therefore an object of the present invention to provide an improved fluid catalyst composition.
~, It is a further object to provide a fluid hydrocarbon ; conversion catalyst which possesses increased density and attrition resistance.
It is another object to provide a dense attrition , . .

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~046480 resistant commercial cracking catalyst which contains silica-alumina hydrogel and a large proportion of crystalline alumino silicates and/or clay.
These and still further objects of the present invention will become readily apparent to one skilled in the art from the following detailed description and specific examples.
Broadly, our invention involves an improved fluid catalyst composition wherein a particulate catalyst of fluidizable size is combined with an inorganic colloid of silica, alumina or silica-alumina having a particle size of less than about 0.05 micron.
More particularly, we have made the surprising dis-covery that if up to about 30% by weight of an inorganic sol of silica, alumina or silica-alumina having a particle size of less than 0.05 micron is absorbed by or into a preformed catalyst particle of fluidizable size (about 50 to 200 microns), a fluid catalyst composition is obtained after normal washing ;
and drying procedures which possesses a significant increase -in both density and attrition resistance.
Catalysts which may be advantageously prepared in accordance with our invention are hydrocarbon-conversion catalysts and particularly fluid petroleum cracking catalysts which contain silica-alumina hydrogel in combination with i large proportions of crystalline alumino silicates and/or clay.
Typical catalysts comprise or contain silica-alumina hydrogels which contain from about 10 to 40% by weight alumina. These hydrogels are formed by any one of numerous prior art proce-dures which involve the gellation of an alkali metal silicate with an inorganic acid or an acid aluminum salt. It is also contemplated that silica alumina hydrogels prepared by the . -: .

10~6~il0 combination of silicate and sodium aluminate under appropriate conditions may be employed. In addition to silica-alumina hydrogel, the present catalyst compositions may contain a substantial quantity of clay such as kaolin. In general, it is found that the overall catalyst compositions may advantageously contain clay in amounts ranging from 20 to 50% by weight of the finished catalyst. In addition to clay, the catalyst may also contain a crystalline alumino silicate zeolite such as synthetic faujasite. Synthetic faujasites which possess a silica to alumina ratio ranging from about

2 to about 6 are readily available in the form of commercial products such as zeolite X or zeolite Y. Preferred zeolites are stabilized by chemical and/or thermal treatment wherein alkali metal ions are removed and replaced by hydrogen or polyvalent metal ions such as rare earth ions. Zeolites or stabilized zeolites identified as Z-14US in U.S. Patent

3,293,192, as well as zeolites identified as CREX and CREY
in U.S. Patent 3,402,996 are readily adapted for use in the present invention. It is also contemplated that the zeolites j 20 may be incorporated in the catalyst compositions in the form of alkali metal zeolites, and during subsequent processing of the catalysts the alkali metal zeolites are converted to a more stable polyvalent metal or hydrogen exchanged form.
A typical catalyst which may be treated in accordance with our invention is prepared by combining an alkali metal silicate with clay such as kaolin and subsequently gelling the silicate by the addition of a mineral acid or carbon dioxide. The gelled clay-silicate mixture is then combined with a desired amount of aluminum salt such as alum or possibly a sodium aluminate to form a silica, alumina clay ~,, , .

~0~6480 ,- .
composite wherein the clay is thoroughly dispersed throughout the mixture. It is also contemplated that crystalline zeol~tes may be combined with the composite in amounts . . . .
, ranging from about 5 to 50% by weight. Subsequent to forma-, tion, the silica alumina clay/crystalline alumino silicate ' composite is formed into discrete particles, preferably by ', spray drying. Spray drying produces a finely divided product ' whic'n in its fluidized form possesses particles on the order ; of 20 to 200 microns. The spray dried product may then be utilized in accordance with the teachings of the present invention set forth in detail subsequently herein.
- The inorganic colloid which is absorbéd by or into the , flui'd catalyst particles preferably comprises a sol of silica, alumina or silica-alumina. This sol contains extremely - finely divided particles of inorganic gel which are less -' than 0.05 micron in size. The sol is typically prepared by ', combining an alkali metal salt of silica, alumina or silica-alumina with water in amounts which produces a sol which , ' cont~ins from about 10 to 50% by weight inorganic colloidal particles. A particularly preferred colloid,is prepared by ~,' mixing 'sodium aluminate (1 to 2 Na2O.A12O3) with sufficient water to produce a soI which contains 20 to 30~ by weight'A12O3. Other preferred sols include a silica ~ol which is prepared by mixing sodium silicate (.2 to 1 Na2O.SiO2) with sufficient water to produce a sol which contains 20 to 40% by weight - -, SiO2. Another preferred sol is a commercially available soi ... .
,, of SiO2 essentially free of alkali metal ions such as "Ludox"

', manufactured by the DuPont Corporation. ' In addition to preparing a sol from synthetic ingredients, , 30 it is found that certain naturally occurring clays, such as *Trademark _5_ . , .. `~'' ' ' ' . , .
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kaolin, which consist at least in part of finely divided silica-alumina particles less than 0.05 microns in size are suitable for the practice of the invention. These ~inely - divided clays are slurried with about 50 to 90% by weight water and are mixed with the catalyst particles in the same manner as the synthetic sol or in combination therewith.
The inorganic colloid is combined with the formed catalyst particles in amounts which impart from about 5 to 30% by weight of the colloid solids on the finished catalyst composition. The inorganic colloid may be conveniently added to the catalyst particles during manufacture of the - catalyst composition subsequent to formation of the particle.
Furthermore, it is contemplated that a catalyst which is I substantially complete, i.e. washed and dried, may be combined with the inorganic colloid and subsequently washed to remove and/or neutralize excess alkali metal, if present, and dried to a desired extent.
; Typical proceaures employed in the practice o~ the invention contemplate combining a spray dried catalyst ` 20 product such as that described above with the desired amount of inorganic colloid. This product is subsequently washed, and exchanged with stabilizing metal ions if desired and finally dried to a desired volatile content. :~
Furthermore, it is contemplated that a commercial ... .
~ catalyst composition which has been spray dried, exchanged, washed i and finally dried may be advantageously treated with the inor-ganic colloids described above. When such a procedure is utilized, the commercial catalyst is combined with the inorganic colloid, and subsequently washed if necessary to remove the excess alkali metal salts and dried to a level of about 5 to 20% total volatiles. In general, the amount of colloid combined 1 , .

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1~9L6480 with the catalyst particles will range from about 5 to 30%
by weight of the finished catalyst. More specifically it is found that colloid can be added to the catalyst to the level of incipient wetness. In other words, colloid is added to the catalyst particle so as to fill the pores of the catalyst but not to coat the catalyst composition with excessive li~uid. It is generally found that the point of incipient wetness is reached when sufficient colloid is added to fill the available pore volume of the catalyst, i.e. those pores having a size of greater than about 4 and less than 10,000 Angstroms, to a level of 70 to 110%.
After combining the colloid with the catalyst particles, the product is subsequently washed or ion exchanged to reduce the alkali metal content to a level of less than about 1%
and preferably less than 0.5% by weight Na2O. As explained above, the colloid may be added to a catalyst which is in the course of preparation or it may be added to a typical .i,, .
prior art catalyst of commerce which has essentially been completed. It is generally found that the completed catalyst t' ' 20 is dried to a level of less than 20% by weight total volatiles `, by drying at a temperature on the order of 200 to 300F.

' The catalysts produced by way of the present invention possess activity and selectivity characteristics substantially , .
the same as or better than those possessed by a catalyst which has not been-treated with the inorganic colloids disclosed herein. This result is particularly surprising in view o~ the fact the inorganic colloid normally is not expected to impart significant catalytic activity, and in fact is considered a diluent by workers skilled in the art. Accordingly, it would be ,.. :!
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., '~'' ., ''' ,:, , -. .,: , o expected that the addition of the diluent colloid would ,' reduce the overall activity of the catalyst composition.
The addition of the inorganic colloid serves to in-- crease the density of the catalyst from about 5 to 30%. Eurther-more, the colloid serves to increase the attrition resistance of - the catalyst which is evidenced by an increase of the so-called - Davison Index and ~ersey Index which are standard methods for testing or evaluating the resistance of a catalyst to -attrition. It is found that the present procedure will - 10 increase the attrition resistance of a typical standard fluid cracking catalyst from a level of about 35 DI to a level of , about 20. This increase in attrition resistance coupled with the increase in density greatly reduces the tendency of the catalyst to escape the recovery systems employed in -~
typical cat-cracking units.
Having described the basic aspects of the present invention, the following examples are given to illustrate ' specific embodiments thereof.
'~, 'E'xamp'le'I
2~ a) A solution of sodium aluminate was prepared by dissolving 450 g of sodium aluminate (~a2O-A12O3-3H2O) in 450 ml of water. This solution was heated to a temperature of 90C.
for 1/2 hour to obtain a colloidal solution of sodium aluminate having a particle size of about 0.01 micron. ,, b) A 450 g sample of commercial cracking catalyst (CBZ-l) which comprised fluidizable (50 to 250 micron) particles of a composite of about 10% rare earth exchanged type Y zeolite, ; about 50% silica alumina hydrogel, and about 40% kaolin clay was thoroughly mixed with 450 g of the aqueous A12O3 colloid obtained in a) above. The mixture was then washed .

~ - 8 -10~ 0 twice with dilute ammonium sulfate solution to lower the Na2O co~tent of the composition to below about 0.85% by weight. The sample was washed free of SO4 ion with water and ~;~ then dried at 400F. for 16 hours.
c) The catalys-t sample obtained in b) above was subjected to chemical and physical analysis to obtain the following data:
`` TABLE I
ANALYSIS DESCRIPTION SAMPLE AND DESCRIPTION

Untreated Treated CB~-l CBZ-l wt. of added A12O3 on catalyst (% Dry Basis~ 0 24 Peak ~eight (x-ray) (mm)87 43.5 Density (g/cc) 0.603 0.688 Water Pore Volume (cc/g) 0.67 0.46 Nitrogen Pore Volume (cc/g3 0.52 0.45 Microactitity (Vol. ~)74.9 68.8 ~ Surface Area (m /g)370.8 329.9 -~ Davison Attrition Index33.6 17.1 Jersey Attrition Index3.8 1.5 .~ The microactlvity values were obtained after heating the catalyst sample to 1050F. using the procedure described by ~i Ciapetta et al, Oil and Gas Journal, October 16, 1967. The Davison and Jersey attrition indexes were obtained as follows:
h, A 7 gram sample is screened to remove particles in the 0 to 20 micron size range. The 20+ micron sample is then sub-!1 jected to a 5 hour test in a standard Roller Particle Size Analyzer using a 0.07 inch jet and 1 inch I. D. U-tube as supplied by the American Instrument Co. of Silver Spring, Maryland. An air flow rate of 21 liters per minute is used.

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Davison Index =
wt. of 0-20 micron material formed during 5 hrs. of testing x 100 wt. of originaI~~-20+ micron fraction Jersey Index =
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wt. of 0-20 micron material formed during 2nd-5th hrs. of test

4 x wt. of original 20+ micron fraction Inspection of the above data reveals that a sample ; treated in accordance withthe teachings of the present inven-tion, possesses both increased density and attrition resistance as compared to the control sample. Furthermore, it is seen ` 10 that the treatment sample retains good cracking activity even though it contains 24% added amorphous alumina which is ordinarily considered to be relatively inactive when compared to crystalline zeolite.
EXAMPLE II
a) A sodium aluminate solution was prepared by mixing 100 g of sodium aluminate with 100 g of water. The solution was heated to about 90C. for about 1/2 hour to obtain an aqueous alumina sol having a particle size on the order of 0.01 microns~
`~ b) A sodium silicate solution was prepared by com-', 20 bining 195 g of sodium silicate solution which contained 8.7%
Na2O and 28% SiO2 with 25 g H2O. The mixture was heated to about 60C. to obtain an aqueous silica sol which contained particles of SiO2 having a size on the order of 0.01 microns.
~, c) Samples of a commercial fluid cracking catalyst (DZ-5) which comprised about 10~ CREY (calcined rare earth ex-changed type Y zeolite) and 90% clay and amorphous silica alumina hydrogel were combined with the inorganic sols prepared in a) and b) above as follows:
1. A 200 g sample of DZ-5 was combined with 200 g of the alumina sol prepared in a) above. The mixture was .'. .

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;~ e,:changed ~rith dilute ammonium sulfate solution and then washed with water to remove SO~ ion.
- 2. A 200 g sample of DZ-5 was combined with 220 g of the silica sol prepared in b) above. The mixture was exchanged with dilute ammonium sulfate solution to ~- remove Na20 and washed with water to remove SO4 ion.
The samples were dried at 1000Fo ~ analyzed, and tested as ~escribed in Example L. The results of the analysis are set forth in Table II below:

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10~80 The above data clearly indicates that the cataiysts of ' samples 2 and 3 which contain the added inorganic sols possess superior attrition resistance when compared to the original catalyst sample' 1. Furthermore, samples 2 and 3 retain an extremely high degree of activity even though these samples contain a large percentage of ordinarily inert amorphous silica or alumina.
' EXAMPLE III
a) A sol of finely divided clay was prepared by combining 30 g of kaolin clay with 70 g of water. The kaolin clay was a fraction of the commercially available grade "Hydrite UF'~
marketed by the Georgia Kaolin Company. The fraction used contained a wide dlstribution of particle sizes with a substan-~ tial portion below 0.05 microns. -;; b) A 50 g sample of the CBZ-l (denslty 0.603) catalyst ' ~ described in Example I was combined with 30 g of the sol described in a) above. The mixture was thoroughly mixed and dried at a temperature of 1000F. Clay particles that were too large to enter the catalyst-pores are remoyed by elutriation.
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The density of the product was found to be 0.64 indicating that about '35% of the clay particles combined with the catalyst resulting in a density increase of about 7%. ,-,, ExAMæLE IV
a) A commercial silica so-~ (Ludox~ was obtained which contained 30% SiO2 ànd a particie size of about .01 microns.
b) A 47 g sample of CBZ-l described in Example I was combined with 23.5 g of Ludox described in a) above. The mixture was dried at 1000F. and the density and attrition ',' resistance wer~determined. The density of the original 30 CBZ-l sample increased from an original,value of 0.603 g/cc ,. . . .

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to 0.710 g/cc.
EXAMPLE V
Samples of CBZ-l catalyst described in Example I were treated with the colloid solution of sodium aluminate described in Example I as follows:
a) Sample 1 was untreated CsZ-l which was used as a control sample for purpose of comparison.
b) Sample 2 was prepared by impregnating a sample of -the finished (washed, rare earth exchanged) CBZ-l catalyst by the procedure set forth in Example I, paragraph b).
c) Sample 3 was prepared by impregnating in process a spray dried sample of CBZ-l, which was not washed or rare earth exchanged, with the sodium aluminate solution~ The impregnated sample was then washed with ammonium sulfate ~' solution and water to remove sodium and sulfate ions. The sample was finally exchanged with a solution of rare-earth chloride. -Samples 1, 2, and 3 prepared above were then subjected ' ,~ to analytical and pilot unit testing. The date obtained is set forth in Table III below.
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SAMPLE NO. 1 2 3 CHEMICAL ANALYSIS:
RE2O3:wt.% 3.8 3.903.77 A123 Wt % 28.9 36.937.8 Na2O:Wt.~ 0.76 0.440.49 SO4:Wt.% 0.60 0.351.88 PHYSICAL ANALYSIS:
Density:gm/cc0.58 0.720.61 DI:gm/cc 32 13 21 JI:gm/cc 2.0 1.82.7 THERMAL ANALYSIS:
3 Hrs. Q 1000F.
SA : m /gm 283 278 311 N2PV : cc/gm0.27 0.270.35 Peak Ht. : mm/BK 81 54 75 3 Hrs.@ 1650 F:
~; SA : m /gm 130 201 217 N2PV :cc/gm0.14 0.210.26 - 20 Peak Ht. :mm/BK 55 52 55 PILOT UNIT DATA ~ 920F,4 C/,40 WHSV
Conversion : V% 70.0 76.5 63.0 H2 : W% 0.02 0.0250.C3 i:, ` C + C : W% 1.1 0.80 0.74 Total C3 : V% 7.3 7.1 6.0 C3 : V% 5.2 5.65.1 Total C4 : V%~ 10.9 11.4 10.7 C4 : V% 3.3 4.04.8 iC4 : V% 6.4 6.35.0 C5+ gasoline : V% 58.5 66.0 53.5 , .
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1046~80 TABLE III (Cont.) .. . . .
SAMPLE NO. 1 2 3 ~ _ _ .
`~ Gaso./Conv. Ratio 0.84 0.86 0.85 Coke : W~ FF 4.7 4.5 3.4 EXAMPLE VI
Samples o the DZ-5 catalyst described in Example II
were treatea with the sodium aluminate sol prepared in Example II, paragraph a) as follows:
a) Sample 1 was an untreated control sample of the DZ-5 catalyst.
b) Sample 2 was prepared by impregnating an in process - sample of DZ-5 which had been spray dried, but which had not . . .
been washed with ammonium sulfate and water to remove sodium and sulfate ions. The impregnation with sodium aluminate was -conducted as set forth in Example II, paragraph c), sub-paragraph ~. 1. . .. :
c) Sample 3 was prepared using a sample ~f finished (washed) DZ-5 catalyst as described in Example II, paragraph c), sub-paragraph 1.
Samples 1, 2, and 3 as prepared above were subjected to ' analytical and pilot plant catalytic cracking testing. The -.
data obtained is summarized in Table IV below.
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10~6480 - TABLE IV
SAMæLE NO 1 2 3 CHEMICAL ANALYSIS:
.
RE2O3 : Wt.% 2.66 1.992.00 A123 : Wt.% 30.1 42.6 Na2O : Wt.% 0.16 0.07 SO4 : Wt.% 0.18 0.91 PHYSICAL ANALYSIS:
Density: gm/cc 0.46 0.59 0.60 DI : gm/cc 38 7 10 JI : gm/cc 4.0 1.21.4 THERMAL ANALYSIS:
3 Hrs. ~ 1000F:
SA m2/gm 331 360 340 N2PV :cc/gm 0.61 0.42 0.37 Peak Ht.:mm/BK 63 49 49 3 Hrs. ~ 1650F:
`.
SA :m /gm 208 273 234 i N2PV :cc/gm 0.38 0.36 0.30 Peak Ht.:mm/BK 42 41 33 - PILOT UNTT DATA @ 920F, 4 c/o 40 r~ SV
Conversion : V%72.0 82.077.0 H2 : W% 0.05 0.045 0.05 '' Cl + C2 : W% 1.38 1.80 1.28 Total C3 : V% 7.8 10.6 8.3 :
;, C3- : V% 5.7 8.06.4 Total C4 : V% 11.4 9.7 11.6 C4 : V% 4.0 3.24.6 iC4 : V% 6.1 5.36.1 C5+ gasGline:V%61.0 70.065.0 ` Gaso./Conv. Ratio 0.85 0.85 0.84 - Coke : W% FF 5.7 6.46.1 ., :

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Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for increasing the density and attrition resistance of a fluidizable hydrocarbon cracking catalyst composition which comprises:
(a) preparing a composite selected from the group consisting of silica-alumina hydrogel, clay, crystalline aluminosilicate zeolites and mixtures thereof, (b) spray drying the composite, (c) combining the spray dried composite with from about 5 to 30% by weight of an inorganic colloid composed of particles less than about 0.05 microns in size selected from the group consisting of silica, alumina, silica-alumina, clay and mixtures thereof, and (d) washing, drying and recovering the catalyst.

2. The method of claim 1 wherein said colloid is alumina derived from sodium aluminate having the formula 1 to 2 Na2O.Al2O3 in aqueous medium.

3. The method of claim 1 wherein said colloid is derived from a mixture of clay and aqueous sodium silicate solution.

4. The method of claim 1 wherein said colloid is derived from silica in an aqueous medium.

5. The method of claim 1 wherein said catalyst is dried to a level of less than about 20% by weight total volatiles.