CA1202612A - Catalyst and catalyst support compositions - Google Patents

Abstract

CATALYST AND CATALYST SUPPORT COMPOSITIONS Catalyst and catalyst support compositions which comprise an acid reacted metakaolin. The compositions may be spray dried and calcined to obtain highly active, dense, attrition resistant fluid cracking catalysts or used in the preparation of formed catalyst supports.

Description

The present invention relates to the preparation of catalytic compositions, more particularly to the preparation of dense, hard, particulate hydrocarbon conversion catalysts which comprise acid reacted metakaolin.
Hydrocarbon conversion catalysts such as fluid catalytic cracking catalysts (FCC) are typically manufactured by spray drying aqueous slurries of catalytically active zeolites and matrix forming components such as inorganic oxide gels and/or clays.
The resulting ca*alysts comprise small particles (microspherec) in which the zeolite crystals are dispersed throughout a matrix of relatively catalytically inactive gel or sol binder and clay.
It has been found that clay, particularly kaolin, due to its reasonable price and availability, constitutes a particularly suitable FCC catalyst component. The prior art describes preparation of clay based hydrocarbon conversion catalysts that have been thermally and/or chemically treated to obtain the desired characteristics.
U.S. 2,485,626 describec the preparation of clay based cracking catalyst wherein kaolin clay is heat treated and reacted with acid to remove alumina from the clay structure. The acid reacted clay is washed Pree of soluble components, and formed into catalyst particles.
U.S. 3,406,124 describes a method for preparing catalysts which contain crystalline aluminosilicate zeolites dispersed in an inorganic oxide matrix. The matrix contains a clay component which is leached with acid to remove a portion of the alumina of the clay ~ ,,' ~2~Z~;~.2 struc~ure as solub~e aluminum salts. The soluble aluminum salts are precipitated as aluminum hydroxide.
While the prior art describes the preparation of hydrocarbon conversion catalysts which may comprise or contain thermally/chemically treated clays, such as calcined/acid leached kaolin, the refining industry is constantly searching for low-cost catalysts which provide an acceptable degree of activity and selectivity combined with substantial physical strength and attrition resistance.
It is therefore an object of the present invention to provide improved catalytic compositions.
It is anothèr object to provide hydrocarbon conversion catalysts which are hard, dense and relatively ine~pensive to manufacture.
It is yet another object to provide highly active, cost effective FCC catalysts which comprise chemically/thermally modified kaolin that may be used in the catalytic cracking of a wide variety of hydrocarbon feestocks.
It is a still further object to provide inexpensive clay-based FCC catalysts which may be blended with more expensive zeolite containing FCC catalyst and used to process feedstocks that are heavily contaminated with metals, sulfur and/or nitrogen compounds.
These and still further objects of the present invention will become readily apparent to one skilled in the art ~rom the following detailed description and specific examples.
Broadly, my invention contemplates improved catalytic compositions (including catalysts and catalyst supports) which contain an acid treated metakaolin that is obtained by heating (calcininy) kaolin and reacting the resulting metakaolin with ~zc~z~

sufficient acid to react with up to about 25 mol percent of the alumina (A12O3) present in the kaolin.
More specifically I have found that dense, hard, attrition resistant catalytic compositions may be prepared from acid treated metakaolin which is obtained by heating (calcining) kaolin to a temperature of about 700 to 910C, and reacting the resulting metakaolin with sufficient acid to react with less than about 25 mol percent, and preferably from about 5 to 15 percent, of the structural alumina present in the metakaolin.
The compositions are formed into particles which may be then heat treated (calcined) at a temperature of about 300-800C to obtain hard attrition resistant catalysts or catalyst supports.
The acid treated metakaolin catalysts described herein have substantially higher activity than the acid leached clays described in the literature. This low cost, high activity acid treated metakaolin provides a significant portion of the total cracking activity of the c~talyst. Catalysts with substantial matrix cracking activity are highly desirable for the cracking o high boiling feedstocks, and for the production of high octane gasoline.
While the process is particularly useful for the manufacture of FCC catalysts which may be used to catalytically crack a wide variety of hydrocarbon feedstocks my invention also contemplates the preparation of catalyst supports which are used in the manufacture of hydroprocessing catalysts such as hydrocracking, hydrodesulfurization and hydrodemetallization catalysts.
The reaction metakaolin is obtained by thermally treating kaolin at a temperature of from about 700 to 910C, and preferably ~00 to gnoo, fv~ a period yreater than about one-quarter hour, and preferably one~quarter to 8 hours, and more preferhly from one~half to 2 hours. The thermal treatment, or calcination step, which may be conducted in the presence of air, converts the raw kaolin into a reactive form which is characterized as metakaolin.
The reactive metakaolln is then reacted with an acid, such as hydrochloric or nitric acid or an acid salt solution thereof such as aluminum chloride, aluminum nitrate, zirconyl chloride, etc~
The quantity of acid reacted with the metakaolin is sufficient to react with from about 2 to 25 and preferably from 5 to 15 mol percent of the alumina (A12O3) present in the metakaolinO The reaction in the case of hydrochloric acid typically proceeds in accordance with the followin~ overall reaction wherein metakaolin has the formula 2 Sio2.Al~O3.

2 SiO Al O + 1 HCl ~ ~2 SiO2.(A12O3)0.9Ho.~] 3 20 HCl To achieve the desired level of acid treatment, the quantity of acid used is equal to or less than about 1.5 mols oE acid per mol of alumina present in the clay. I have found that as little as 0.25 mols of acid 25 per mol of alumina is sufficient to provide the desired acLd reacted metakaolin product in less than about 24 hours. The most preEerred level of acid is about 0.50 to 1.0 mol of acid per mol alumina in the metakaolin.
The desired ~uantity of acid is combined with 30 sufficient water to provide from about 2.0 to 20 parts by weight acid solution per part by weight metakaolin.
The reaction with acid is conducted at a temperature of Erom about 60 to 100~C for a period of from about 1 to 24 hours. The resulting acid/metakaolin reaction product contains from about S to 50 percent by weight clay solids admixed with a liquid phase which comprises an aqueous solution o a complex acid/aluminum reaction product which has a pH from about 2.0 to 4Ø This acidic aluminum reaction product solution together with the acid leached metakaolin solids comprises the binder or intermediate whlch is used in the preparation of the catalysts and catalyst supports contemplated herein.
The ratio of the acid leached clay solid to complex acidic aluminum species in solution is from about 8/1 to 9.8/1, preferably 9/1 to 9.5/1 parts by weight.
To obtain a cracking catalyst which comprises the acid-metakaolin reaction product described above, the acid-metakaolin reaction mixture is spray dried or otherwise formed into particles of desired shape and size. It is also contemplated that the acid reacted metakaolin reaction product may be reaated with sufficient base to raise the pH of the reac~ion mixture to a level of about 5.0 to 9.0 in order ~o precipitate the soluble aluminum component prior to forming~
Furthermore, the aLumina components may be auto-precipitated by holding the reactlon ~ixture fa~ a period in excess of about 3 haurs at a temperature a 60 to 100C using high clay solids levels.
To prepare fluid cracking cataly~ts (FCC) the acid rected metakaolin i~ mixed with water to obtain a spray drier feed slurry which contains from about 20 to 60 percent by weight solidsO The slurry is then spray dried using conventional techniques to obtain microspheroidal FCC catalyst partlcle~ which are then calcined either prior to or during use at a temperature of ~rom about 300 to 800C. The~e calcined particles :~2(~

may then be ion exchanged and/or washed to remove undesirable soluble salts. The FCC catalysts o the present invention possess a surface area of abou~ 200 to 600 m ~g~ a denslty of about 0.50 to 0.30 g/cc, and a microactivity of about 40 to 80 volume percent conversion after steaming at 1350F with 100 percent steam for 8 hours (ASTM method D3907). Furthermore, the catalysts possess a high degree of attrition resistance as determined by the methods disclosed in U~S. 4,247,~20.
The FCC catalysts of this invention are particularly cost effective for the catalytic cracking of residual hydrocracking feedstocks which contain high levels of contaminating metals (Ni ~ V), sulfur and/or nitrogen. The catalysts may be blended with standard zeolite promoted cracking catalyst of the type described in U.S. 3,867,308 and 3,957,689. It is anticipated that physical blends which contain from about 20 to 80 weight percent zeolite FCC in admixture with the ~CC catalysts of this invention will be effective for processing residual ~eeds that cause rapld deactivation of conventional catalysts by metals contamination.
In the event the acid treate~ metakaolin contemplated herein is utilized to prepare supports, such as used in the preparation o hydroprocessing catalysts, the acid metakaolin reaction mixture described above is mixed with mlnor amounts of water and ~ormed into extrudates, pills or granules using conventional forminy techni~ues~ ~t is also conte~plated that the acid reacted metakaolin may be reacted with a base ~o precipitate alumina priox to orming the catalyst support~. The re~ultant formed partlcles are then sub~eated to aalcinati.on either ~2~Q;~

prior to or during use at a temperature of from about 300 to 800~C to obtain hard attrition resistant particles. The resulting calcined particles may then be cornbined with catalytically active metals such as selected from group VI ancl group VIII of the Periodic Table to obtain catalysts useful for hydrocracking and hydrodesulfurization, demetallization and so forth. In particular, it is anticipated that from about 1 to 20 weight percent non~-noble metals, such as cobalt, molybdenum/ chromium and nickel may be impregnated or placed upon the catalyst supports contemplated herein using conventional techniques. In addition it is contemplated that from about O.I to 2 weight percent noble metals such as platinum, palladiu~ and rhodium may be combined with the supports to obtain useful, catalytically active products.
Havlng described the basic ~spects of the present invention, the followlng examples are given to illustrate the specific embodiments thereof. The catalytic activity, expressed as volume percent conversion, of the cracking catalysts de~aribed in the examples was determined using the procedure of ASTM-D3907.

Example 1 This example describes preparation of an acid reacted metalcaolin catalytic cracking catalyst of the present invention. 67.5 ml of 37~0% ~lCl was diluted to about 600 ml total volume and 200 g of metakaolin, which had been prepared by calcining Icaolin about 50 minutes at 840C in a rotary calciner r was added. The resulting slurry ~a refluxed for 8 hours. The product was filtered, washed free of Cl , dried in a forced 1 Z~!Z~ ~

draft oven and groundO This sample had a surface area of 284 m /gl an alumina content of 38~8% and a catalytic microactivity of 40~ 7 after an 8 hour, 732C, 100~ steam deactivation.

Example 2 This example uses the same HCl level and concentration as well as the same metakaolin set Eorth in Example 1, and demonstrates that a high ~urface area catalyst is produced when the acid reaction period is extended to 60 hours. 13.5 ml 37.0% HCl was diluted ~o 12G ml, 40 9 of the metakaolin desc~ibed in Example 1 was added, and the resulting slurry was aged at 107C
in a sealed teflon bottle for 60 hours. The slurry was then filtered, washed Cl free and oven dried at 15 121~Co The resulting product had a surface area o~
436 m /g, an alumina content of 36.6% and a microactivity o 39~9 after the steam deactivation.

Example 3 This example indicate~ that higher levels of acid than used in Examples 1 and 2 also given a high su~face area catalyst. 59,0 ml of 37.0% HCl was dlluted to 300 ml, and ac~ded 100 g of the same metaka~lln as in Example 1. The resulting slurry was refluxed about 8 hours, filtered, washed Cl free and oven dried.
This sample had a surface area of 277 m /g~ an alumina content of 43.8% and a catalytic activity of 34.8% after the steam deactivation.

Example 4 This example and examples 5-7 illustrate that undesirably hi~h levels of HCl red~ce the alumin~
content of the catalyst produat and ~edua2 its _9~

~t~

activity~ 202~5 ml 37.0~ EICl diluted to 750 ml, and 200 g of the same metakaolin of Example 1 was added. A
part of the resulting slurry was removed after one-half hour a~ reflux, filtered, washed Cl free and oven dried. This sample had a surace area o~ 157 m2/g, an alumina content of 33.3~ and an activity of 10.7 after steam deactivation.

Exam~le 5 This sample was prepared by the ame procedure as Example 4, except that 270 ml 37~ HCl wa~ used. The resulting cataly6t product had a sur~ace area of 232 m /g, an alumina content of 23.64 and an activity of 13~4 after the steam deactivation.

Example 6 This ~ample was prepared by the same procedure as Example 4, except that 337.5 ml 37~a~ HCl was used, Thls product had a ~urface area 337 m2/~, an alumina content of 14.1% and an aativity ~f 7.~ a~te~ steam deactivation.

Example 7 This sample prepared by the same procedu~e a~
Example 4, except that 4Q5 ml 37.Q% HCl was used, ~bis product had a surface area of 48~ m2/9~ and alumin~
content of 6.18% and an actlv~ty ~ 7.0~ afte~ ~team deactlvation.
Table I below summarlze8 the ~sult~ a~ ~xamples 1-7.

~ln-TABLE I

Microactivity of Acid Reacted Metakaolin Cracking Catalyst as Function of Acid Level ~ Stoichiometric Time at Reflux Surface Area ~ R12O3 in 5 Example ~ ~Cl (hr5.) (m /g)Leached Clay Microactivity 1 17 8 284 38.8 40.7 2 17 60 436 36.6 3~.9

3 29 8 277 43.8 34.8

4 50 1/~ 157 33.3 ~0.7 ~1 ~7 1/2 232 23.6 13.
6 83 1/2 337 14.1 7.5 7 100 1/2 488 6.18 7.0 1. A~TM-D3907 microactivity test after an 8 hour, 732C, 100% steam deactivation (vol.
conversion).

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Example 8 This example shows that the temperature used in the calcination of the clay to obtain metakaolin affects the rate of surface area formation. 100 g of a calcined kaolin prepared by heating kaolin clay for about 50 minutes at 732C was added to separate solutions of 37.1 ml 37.0~ HCl diluted to 330 ml. The resulting mixtures were aged for 16, 44 or 51 hours.
The results summarized in Table II indicate that while this metakaolin is slower reacting than the metakaolin (840C) used in Examples 1-7, high surface area products are obtained when long acid-reaction times are used.

TABLE II

Surface Area of 17% Stoichiometric HCl Reacted Metakaolin (50 min. @ 732C) Time Q 100C Surface Area (m2/g) 4~ 296 Example 9 This example shows the effect of acid solution volume/concentration on surface area development.
Using the metakaolin of Example 1 33.5 ml quantities of 37 percent HC1 (representing 17 mol % of the acid required to react with the alumina present in the metakaolin) were diluted with water to obtain solutions which ranged from 125 to 300 ml in volume. Table III
se~s forth results for 6 samples. Although all products have high surface area indicating good catalytic activity, the third or fourth samples appear to b timum concentration levels.

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TABLE III

Effect of ~cid Concentration on Surface Area of Reacted Clay Productl Sample No. Reaction Siurry (Composition) Surface Area (m3~g) 1 . 33.5 ml 37% HCl diluted to 300 ml + 100 g metakaol~n (as per Ex~mple 1~ 386 2 n ~ 250 Ml + " n l~ 319 ~ n 200 ml + n ~ 1~ 378 4 n n 175 ml + n n i~ 404 ~ ~ n 150 ml + ~ n ~ 315 6 u .- 125 ml f n n ~ 268 1. All preparations were at 17% of stoichiometric HCl, with 60 hr. age at 100C in teflon bottles.

Examp]e 10 This example shows that nitric acid can be used in the preparation of the products of the present invention. 19.3 ml concentrated HNO3 was diluted to

5 225 ml, and 75 g metakaolin (calcined 50 minutes at 871C) was added. Three samples of the mixture were reacted in separate teflon bottles for 4, 6 and 8 hours at 100C. The results, set forth in Table IV, show that the high surface area product is formed after about about 6 hours (Samples 2 and 3).

TABLE IV

Dilute NHO3 Reacting of Metakaolin Sample No. Hot Age Time (hrs.) Surface Area (m /g) 12~

Example 11 This example shows that selected calcination conditions reduce the reaction time required to obtain hlgh surface area products. Separate samples of kaolin were put into a hot furnace at temperatures ranging from 650 to 927C for one hour. S0 g samples o each of the above calcined clays were slurried in 150 ml H2O containing 16.9 ml concentrated HCl. The 50 g samples were divided into 3 separate samples and reacted in teflon bottles for 4, 8 or 16 hours. The results, given in Table V, indicate the most effective calcination temperature is 850 to 875C. Clays calcined at 927C exhibited much lower reactivi~y.
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-lb -~ABLE V

Product Surface Area 2S a Function of Calcination Temperature and Reaction Time Calcination Temp. (C) 650 732 788 843 871 899 927 5Reaction Time, 4 hrs. 87 31 28 184 126 148 25 n n 8 hrs. 25 18 25 340 338 219 28 n 16 hrs. 24 47 36 296 457 220 36 p~

1. .~11 kaolin calcined 1 hour at the indicated ~emperature.

~z~ z Example 12 This example shows that low acid levels can be used to obtain the product of this invention. 225 9 of calcined kaolin (calcined either one-half hour at 899C, 1 hour at 871C or 1 hour at 843C) was slurried in 675 ml solution containing 19.2 ml concentrated HCl. The resulting slurries were boiled 16 hours under reflux. Each slurry sample was filtered, washed to remove CL and oven dried. The results, given in Table VI, indicate substantial surface area development even at this relatively low acid level.
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~18-TABLE VI

Use of 1/24 Stoichiometric HCl on Various Metakaolins Clay Calcination Conditions Reaction Time (~rs.) Surface Area (m /g) 1/2 hr. @ 899C 8 206 5 I~ n 12 287 D n 14 300 hr. @ 843C 8 198 n n 12 231 lC n n 14 251 ~I n 16 2 51 1hr~ ~ 871~C 8 196 n n lQ 252 u n 12 270 1~ ~ n 14 278 Example 13 This example shows that a salt which can generate H via hydrolysis can be used in place of mineral acids. 75 g portions of metakaolin (calcined 1/2 hr.
5 at 900C) were added to 900 ml solutions containing varying amounts of AlC13.6H2O. The slurries were refluxed, the pH adjusted to 7.0 with lg~ NH~OH, filtered, washed Cl free and oven dried. The results, given in Table VII, c].early show the development of very high surface area materials even at low AlC13.6H2O levelsO

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TABLE VII

Effect of Level of AlC13 6~2O on Rate of Surface Area Development g AlCl3 6E2O/75 g Metakaolin Time at Reflux (Hrs.~ Surface Area (m /9)2 75.3 5 l/2 278 37.7 8 333 37.7 16 418 25.1 8 313 25.1 16 390 18.9 8 305 lO18.9 l~ 428 12.6 8 256 12.6 16 410 ~2(~ZfJ~

Example 14 This ex~mple shows that ammoniation of the acid reacted clay slurry just prior to filtration enhances activity. A reacted clay slurry was prepared and reacted as in Example 1 except that after reacting the slurry pH was adjusted to 6.0 with 14% NH40H prior to filtration. The surface area was 326 m2/g and the activity was 49.2, which is substantially higher than the 40.7 observed for the product obtained in ~xample 1.

Example 15 This example shows that enhan_ed activity can be obtained by precipitating alumina in the presence of acid reacted metakaolin. 5,400 ml concentrated HCl was diluted to about 48 1 with water and 16,000 g metakaolin (calcined 1 hour at 732C) was added. The resulting mixture was reacted under reflux for 48 hours, filtered, washed 2 times with 10 gallons hot H2O. This product had a surface area of 2a3 m2/g.
50 g (dry basis, 104.2 g as is) of this filter cake was 20 dispeesed in 1/2 1 H2O containing 26.3 g AlC13.6H2O. The pH adjusted to 6.0 with 14%
N~140H to precipitate alumina and the product was filtered, washed 2 times with 1/2 1 hot ~12 and dried at 120C. The alumina treated sample had an activity 25 of 45.6 versus 36.1 for the untreated sample.

Example 16 This example shows the preparation of a gelled acid treated metakao]in of the present invention. 150 g of kaolin clay calcined 1/2 hour at 900C was added to 1.0 30 1 of solution containin~ 50.7 ml of 37% HCl. Half the slurry boiled under reflux for 4 hours and the other ~2~ .Z

hal~ was boiled for about 8 hours. Both samples were briefly cooled, the pH adjus~ed to 6.0 with 14% NH40H
to gel the alumina components, the slurry filtered and washed 2 times with 1/2 1 hot deionized H2O and oven dried. The surface areas of the 4 and B hour refluxed samples were 295 and 402 m /g. The catalytic activity of the 4 and 8 hour refluxed samples were 46.4 and 50.5 respectively following the procedure o ASTM-D3907.

Example l?
This examplè shows that signi~icant enhancement in activity is observed by addition of boehmite to the gelled acid treated metakaolin of the present invention. 200 g kaolin clay calcined 1/2 hour at 900C was added to 2.0 1 solution containing 67.9 ml 37% HCl and boiled under reflux for 24 hours. To four separate cooled samples of the above slurry, varying amounts of boehmite were added the p~l was adjusted to 7.0 with 14% NH40H, the slurry filtered and the ~ilter cake washed 2 times with 1/2 1 hot deionized H2O. The samples were dried and the cracking catalytic activity of each sample was determined. The activity data, summarized in Table VIII shows that boehmite addition to the gelled acid treated metakaolin results in significant activity improvement.

TABLE VIII

fect of Added Boehmite on Gelled Acid Reacted Me~akaoli~ Catalysts Added Bcehmite Yol. ~ Conversionl 50~0 t~ypical) 59.9 17.5 60.0 ~

20.0 59.0 Pa 22.5 - ~9.3 1. ASTM-D3907 Volume ~ conversion measured at 499C J 16 WHSV, 3 C/O
after an 8 hour, 732C~ 1OO~ steam treatment.

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E~ample 1~
Samples of hydrothermally acid treated metakaolin were prepared by adding 25 g kaolin (calcined l/2 hour at 900C) to 125 ml ~2 containing 8.5 ml 37~ HCl and heating for the time/temperature indicated in Table IX
in teflon lined hi.gh pressure reactors. The slurries were cooled, diluted with water to make a stirrable slurry, the pH adjusted to 7.0 with 14~ NH40H, filtered, washed 2 times with l/2 1 hot H20 and oven dried at 120C~ The activity of the hydrothermally acid treated metakaolin is significantly increased relative to the lOO~C refl~xed sampleu \

TABLE IX

Effect of ~igh Temperature Acid Treatment Reaction Temp. Reaction Time Surface Area Activity (C) (~rs.) (~2~gl~ (Vol.~ Cov.) 100 (Typical) 4-~4 400 5Q (Typical) 140 ~ 413 57.9 ~
~3 140 ~8 526 59.2 ~~

165 6 - 392 58.0 1. Surface area measured after a 1 hour at 593C thermal treatment.

2. ASTM-D3907 volume ~ conversion measured after an 8 hour, 732C, 100% steam treatment.

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The above Example~ cl.early in~icate that valuable catalyst compositions may be obtained using the teachings of my invention.

Claims (18)

I CLAIM:

1. A catalytic composition comprising an acid reacted metakaolin, said composition being obtained by heating kaolin at a temperature of 700 to 910°C for a period in excess of about one-quarter hour to obtain metakaolin, and subsequently reacting at a temperature in excess of about 60°C said metakaolin with sufficient acid selected from the group consisting of hydrochloric, nitric acids, salts and mixtures thereof to react with up to about 25 mol percent of the alumina present in said metakaolin.

2. The composition of claim 1 wherein from about 5 to 15 mol percent of the alumina in the metakaolin is reacted with acid.

3. The composition of claim 1 wherein the reacted alumina is precipitated.

4. The composition of claim 1 which is washed and spray dried to obtain a fluid catalytic cracking catalyst.

5. The composition of claim 4 admixed with a zeolite containing fluid cracking catalyst.

6. The composition of claim 5 wherein the zeolite containing catalyst comprises a zeolite selected from the group consisting of Type X, Y and ZSM zeolite dispersed in an inorganic oxide matrix.

7. The composition of claim 5 wherein the zeolite catalyst comprises from about 10 to 90 percent by weight of the composition,

8. The composition of claim 1 which contains particulate alumina.

9. The composition of claim 3 wherein said alumina is precipitated by the addition of a base.

10. The composition of claim 9 wherein said base is ammonium hydroxide.

11. A method for preparing a catalytic composition which comprises:
(a) calcining kaolin at a temperature of 700 to 910°C for a period in excess of about one-quarter hour to obtain metakaolin;
(b) reacting at a temperature in excess of about 60°C said metakaolin with sufficient acid to react with up to 25 mol percent of the alumina present; and (c) forming the mixture into catalyst particles.

12. The method of claim B wherein the product obtained in step (b) is reacted with a base to precipitate soluble alumina components prior to step (c).

13. The method of claim 8 wherein said acid is selected from the group consisting of hydrochloric, nitric acids and salts thereof.

14. The method of claim 8 wherein said mixture is formed by spray drying, extruding, pilling or granulating.

15. The method of claim 8 wherein said catalyst particles are heated to 300 to 800°C.

16. The method of claim B wherein said kaolin is calcined at step (a) for a period of about one-quarter to 8 hours.

17. A method for cracking hydrocarbons which comprises reacting a hydrocarbon feedstock with the catalyst of claim 4 or 5, under catalytic cracking conditions.

18. A method for cracking hydrocarbons which comprises reacting a hydrocarbon feedstock with the catalyst of claim 6 or 7 under catalytic cracking conditions.