FR2531875A1 - CATALYTIC COMPOSITION AND PROCESS FOR PREPARING THE SAME - Google Patents

Abstract

THE INVENTION RELATES TO A CATALYTIC COMPOSITION WHICH INCLUDES A METAKAOLIN HAVING REACTED WITH ACID. ACCORDING TO THE INVENTION, THE COMPOSITION IS OBTAINED BY HEATING KAOLIN AT A TEMPERATURE OF 700 TO 910C FOR MORE THAN A QUARTER OF AN HOUR TO OBTAIN METAKAOLIN, AND SUBSEQUENTLY THE METAKAOLIN IS REACTED WITH SUFFICIENT ACID SELECTED IN THE GROUP CONSISTING OF HYDROCHLORIC AND NITRIC ACIDS, THEIR SALTS AND THEIR MIXTURES TO REACT WITH UP TO ABOUT 25 MOLES OF THE ALUMINA PRESENT IN METAKAOLIN. THE INVENTION APPLIES IN PARTICULAR TO FLUID CATALYTIC CRACKING.

Description

The present invention relates to the preparation of compositions

  catalysts, and more particularly to the preparation of dense, hard and particulate hydrocarbon conversion catalysts which comprises metakaolin reacted with the acid. Hydrocarbon conversion catalysts such as fluid catalytic cracking (FCC) catalysts are typically manufactured by spray-drying aqueous slurries of catalytically active zeolites and matrix-forming components such as inorganic oxide gels and / or clays. Catalysts resultants include small particles (microspheres) where the zeolite crystals are dispersed throughout a matrix of a gel binder or relatively catalytically

inactive and clay.

  It has been found that clay, especially kaolin, because of its reasonable cost and availability, is a particularly suitable FCC catalyst component. The prior art discloses the preparation of clay-based hydrocarbon conversion catalysts which have been thermally and / or chemically treated for

  obtain the desired characteristics.

  U.S. Patent No. 2,485,626 describes the preparation of a clay cracking catalyst where kaolin clay is heat treated and reacted with an acid to remove alumina from the structure of the clay. clay Acid-reacted clay is washed to rid it of soluble components and is formed

in catalyst particles.

  U.S. Patent No. 3,406,124 discloses a process for preparing catalysts which contain crystalline aluminosilicate zeolites dispersed in an inorganic oxide matrix. The matrix contains a clay component which is leached with the acid to remove a portion of the crystalline aluminosilicate zeolites. alumina from the structure of clay in the form of soluble salts of aluminum Soluble salts of aluminum

  precipitate as aluminum hydroxide.

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  While the prior art describes the preparation of hydrocarbon conversion catalysts which can

  understand or contain clays thermally / chemically

  In addition to being treated as calcined / acid leached kaolin, the refining industry is constantly seeking low cost catalysts with an acceptable level of activity and selectivity in combination with substantial physical resistance and attrition resistance. . The present invention therefore has as its object

  improved catalytic compositions.

  Another subject of the present invention is conversion catalysts for hydrocarbons which are hard,

  dense and relatively inexpensive to manufacture.

  The object of the present invention is to produce

  very active FCC catalysts and a cost-effective price that-

  chemically / thermally modified kaolin which can be used in the catalytic cracking of a

  wide variety of hydrocarbon feedstocks.

  Another object of the present invention is to provide inexpensive clay-based FCC catalysts which can be blended with more expensive FCC catalysts containing zeolite and which are used for the treatment of high feedstocks.

  contaminated with metals, sulfur and / or nitrogen compounds.

  These and other objects of the present invention will become more apparent upon reading the

  following description as well as examples.

  In general, the present invention relates to improved catalyst compositions (including catalysts and catalyst supports) which contain an acid-treated metakaolin obtained by heating (calcining) kaolin and reacting the resulting metakaolin with sufficient of acid to react up to about 25 mole% of the alumina (A 1203) present

in kaolin.

  More particularly, we found that we could

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  prepare dense, hard and attrition resistant catalyst compositions from acid-treated metakaolin obtained by heating (calcining) kaolin to a temperature of about 700 to 910 C, and reacting the resulting metakaolin with sufficient acid to react with less than about 25 mole%, and preferably about 5 to 15% of the structural alumina present in the metakaolin. The compositions are formed into particles that can then be heat treated (calcined) at a temperature of about 300-800 C to obtain hard and resistant catalysts

  attrition or catalyst supports.

  The acid-treated metakaolin catalysts described herein have significantly higher activity than

  acid-leached clays described in the literature.

  This acid-treated, low-cost, acid-treated metakaolin forms a substantial portion of the total catalyst cracking activity. Catalysts having substantial matrix cracking activity are highly desirable for cracking feedstocks. with high boiling point, and for the production of gasoline

with high octane number.

  While the process is particularly useful for the manufacture of ECC catalysts which can be used for the catalytic cracking of a wide variety of hydrocarbon feedstocks, the present invention also contemplates the preparation of catalyst feedstocks which In Catalonia, hydrotreating catalysts are used as catalysts.

  hydrocracking, hydrodesulphurisation and hydrotreating

  demetallization. The reaction metakaolin is obtained by thermally treating kaolin at a temperature of the order of 700 to 910 C and preferably from 800 to 900 ° C, for more than about a quarter of an hour and preferably between a quarter of an hour. hour and 8 hours, and better between half an hour and 2 hours The heat treatment, or step of

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  calcination, which can be undertaken in the presence of air, converts raw kaolin into a reactive form which is

  characterized as metakaolin.

  The reactive metakaolin is then reacted with an acid, such as hydrochloric or nitric acid or its acid salt solution such as aluminum chloride, aluminum nitrate, sodium chloride, and the like.

zirconyl and others.

  The amount of the acid reacting with the meta-

  kaolin is sufficient to react with about 2 to 25 and preferably 5 to 15 mole% of the alumina (M 1203) present in the metakaolin. The reaction in the case of hydrochloric acid typically occurs according to the following general reaction. the metakaolin has the formula 2 Si 02 o A 1203 Si OM O 3 i (1) 2 Si O 2 A 1203 + 1 H Cl 2 Si 2 (A 1203) 0.9 H 0.63 + 0.2 Al C 13 + 0.4 HCl To obtain the desired level of acid treatment, the amount of acid used is equal to or less than about 1.5 moles of acid per mole of alumina present in the It has been found that as little as 0.25 moles of acid per mole of alumina is sufficient to produce the metakaolin reacted with the desired acid in less than about 24 hours. acid is in the range of 0.50 to

  1.0 mole of acid per mole of alumina in metakaolin.

  The desired amount of acid is combined with sufficient water to produce about 2.0 to 20 parts by weight of acidic solution per part by weight of metakaolin. The reaction with the acid is conducted at a temperature of

  in the range of 60 to 100 C for about 1 to 24 hours.

  The resulting acid / metakaolin reaction product contains about 5 to 50% by weight of solid clay in admixture with a liquid phase which comprises an aqueous solution of an acid / aluminum complex reaction product having a pH of 2.0 to 4.0 This acid solution of the alumina reaction product with the acid-leached solid metakaolin forms the binder or intermediate which is used for the preparation of the catalysts and catalyst supports contemplated herein. the ratio of the acid-leached solid clay to the complex of the acidic aluminum in solution is of the order of 8/1 to 9.8 / 1 and preferably

from 9/1 to 9.5 / 1 parts by weight.

  To obtain a cracking catalyst which contains the acid-metakaolin reaction product described above, the acid-metakaolin reaction mixture is spray-dried or otherwise formed into particles of a desired shape and size. It is also contemplated that the reacted metakaolin reaction product can be reacted with the acid with sufficient base to raise the pH of the reaction mixture to a level of about 5.0 to 9.0 to precipitate the aluminum component In addition, the alumina components can be self-precipitated by maintaining the reaction mixture for more than about 3 hours at a temperature of 60 to 1000 ° C. using

high levels of solid clay.

  To prepare fluid cracking catalysts (FCC), the acid reacted metakaolin is mixed with water to provide a spray dryer feed slurry which contains about 20 to 60% by weight solids. The slurry is then spray-dried using conventional techniques to obtain microspheroidal particles of an FCC catalyst which is then calcined either before or during use at a temperature of about 300 to 8000 C. These calcined particles can then be exchanged The FCC catalysts of the present invention have a surface area of about 200 to 600 m 2 / g, a density of about 0.50 to 0.80 g, and / or are washed to remove undesirable soluble salts. / cc and a microactivity of about 80% by volume of conversion after stoving at 7320 C

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  with 10% / o steam for 8 hours (ASTM D 3907 method).

  Moreover, the catalysts have a high degree of resistance to attrition as determined by the

  methods disclosed in US Patent No. 4,247,420.

  The FCC catalysts according to the invention are of particular interest for the catalytic cracking of hydrocracking residual feedstocks which contain high levels of contaminating metals (Ni and V), sulfur and / or nitrogen. Catalysts can be blended with a standard zeolite-activated cracking catalyst of the type disclosed in US Pat. Nos. 3,867,308 and 3,957,689. Physical mixtures which contain about 20 to 80% by weight of mixed zeolite FCC are believed to be present. with the FCC catalyst according to the invention will be effective for the treatment of residual feedstocks which cause rapid deactivation of conventional catalysts by contamination

metals.

  In the case where the acid-treated metakaolin contemplated herein is used to prepare supports, such as those used for the preparation of hydrotreatment catalysts, the metakaolin acid reaction mixture described above is mixed with minor amounts of water and is formed into extrudates, pills or granules an

  using conventional shaping techniques.

  It is also contemplated that acid reacted metakaolin can be reacted with a base to precipitate alumina prior to formation of the catalyst supports. The resulting formed particles are then

  calcined either before or during use

  The resulting calcined particles can then be combined with catalytically active metals such as those selected from group VI and from group VIII of the Periodic Table to obtain hard particles and resistant to attrition. obtain catalysts useful for hydrocracking and hydrodesulfurization, demetallization

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  and so on In particular, it is believed that one can impregnate or place on the catalyst supports envisaged here, using conventional techniques, of the order of 1 to 20% by weight of non-noble metals such as cobalt, In addition, it is contemplated that about 0.1 to 2% by weight of noble metals such as platinum, palladium and rhodium can be combined with the supports to obtain products.

useful and catalytically active.

  Having described the basic aspects of the present invention, the following examples are given to illustrate the specific embodiments thereof.

  catalytic, expressed as a percentage by volume of conver-

  of the cracking catalysts described in

  examples was determined using the process of.

the American standard ASTM-D 3907 o

EXAMPLE 1

  This example describes the preparation of an acid reacted metakaolin catalytic cracking catalyst according to the invention. 67.5 ml of 37.0% HCl were diluted to a total volume of about 600 ml. metakaolin, which was prepared by calcining kaolin for about 50 minutes at 840 ° C. in a rotary calciner, was added. The resulting slurry was refluxed for 8 hours. The product was filtered, washed to remove Cl, dried in a draft oven

  This sample had a superficially

  284 m 2 / g, an aluminine content of 38.8% and a catalytic microactivity of 40.7 after deactivation at 100% steam for 8 hours at 732 ° C.

EXAMPLE 2

  In this example, the same level and the same concentration of HCl and the same metakaolin as in Example 1 are used and it demonstrates that a catalyst with a high surface area is produced when the reaction time with the acid is After 60 hours, 13.5 ml of HCl was diluted to 37.0%, 120 ml, 40 g of the metakaolin described in Example 1 were added and the resulting slurry was examined at 1070 C in a The slurry was then filtered, washed to separate it from Cl and oven dried at 12 ° C. The resulting product had a surface area of 436 m 2 / g, an alumina content of 36.6% and a microactivity of 39.9

after steam deactivation.

EXAMPLE 3

  This example indicates that higher acid levels than those used in Examples 1 and 2

  also gave a catalyst with a high surface area.

  59.0 ml of 37.0% HCl were diluted to 300 ml, and the same metakaolin was added as in Example 1. The resulting slurry was refluxed for about 8 hours, filtered. washed to remove Cl and oven dried This sample had a surface area of 277 m 2 / g, an alumina content of 43.8% and an activity

  catalytic 37.8% after steam deactivation.

EXAMPLE 4

  This example and Examples 5-7 illustrate that too high levels of HCl reduce the alumina content of the product catalyst and reduce its activity. 202.5 ml of 37.0% HCl diluted to 750 ml and 200 ml were added. From the same metakaolin as in Example 1 A portion of the resulting slurry was removed after half an hour at reflux, filtered, washed to remove Cl and oven dried. This sample had a surface area of 157 m 2 / g, an alumina content of 33.3% and a

  activity of 10.7 after steam deactivation.

EXAMPLE 5

  This sample was prepared by the same process

  than in Example 4, but using 270 ml of 37% HCl.

  The resulting product catalyst had a surface area of 232 m 2 / g, an alumina content of 23.66% and an activity of

  13.4 after steam deactivation.

EXAMPLE 6

  This sample was prepared by the same process as in Example 4, but using 337.5 ml of 37.0% HCl. This product had a surface area of 337 m 2 / g, an alumina content of 14.1% and an activity of 7.5%

  after steam deactivation -

EXAMPLE 7

  This sample was prepared by the same procedure as in Example 4, except that 405 ml of HCl at 37.0% was used. This product had a surface area of 488 m 2 / g, an alumina content of 6.18% and a

  activity of 7.0% after steam deactivation.

  Table I below summarizes the results of the

Examples 1-7.

TABLE I

  Microactivity of a metakaolin cracking catalyst reacted with acid depending on the level of acid

Example N

  % stoichiometry Reflux time H Cl (-h) 1/2 1/2 1/2 1/2

Superficial area

sky (m 2 / g) A 1203 in clay

lessivée-

  38.8 36.6 43.8 33.3 23.6 14.1 6.18 1 Microactivity test according to ASTM D 3907 after deactivation at 100% steam, 8 hours, 732 ° C (percentage conversion) ) w -y

Microphone-

  activity 1, 7 39.9 34.8, 7 13.4 7.5 7.0 o

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EXAMPLE 8

  This example shows that the temperature used for the calcination of clay to obtain metakaolin

  affects the rate of formation of the surface area.

  100 g of a calcined kaolin clay prepared by heating kaolin clay for about 50 minutes at 732 C were added to separate solutions of 37.1 ml of 37.0% HC 2 O, diluted to 330 ml. The resulting mixtures were visualized for 16, 44 or 51 hours. The results summarized in Table II

  indicate that while this metakaolin responds more slowly

  Although the metakaolin (840 C) used in Examples 1-7, products with a high surface area are obtained.

  when long acid reaction times are used.

TABLE II

  Superficial area of metakaolin reacted with HCl at 17% stoichiometry (50 min at 732 C) Time at 100 C Surface area (m 2 / g)

16,128

44,296

51,303

EXAMPLE 9

  This example shows the effect of the volume of the solution

  acid / concentration on the development of the super-

  Using the metakaolin of Example 1, 33.5 ml of 37% HCl (representing 17 mole% of the acid required for reaction with the alumina present in the metakaolin) were diluted with water to obtain solutions with a volume between 125 and 300 ml Table III gives the results for six samples Although all the products have a high surface area indicating a good catalytic activity, the third or fourth sample seems to represent

  optimal levels of concentration.

TABLE III

  Effect of concentration of acid on the surface area of the product

of reacted clay 1.

exchanged

  Sample No. 33.5 ml 37% HCl diluted with 11 ml (composition) 300 ml + 100 g metakaolin (as

example 1

  Ml / ml ml + ml + ml + ml + T + 1 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 1 stoichiometric with aging

  60 hours at 100 C in Teflon bottles.

ru J t w Co 1 A ll Ir "T Il I"

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EXAMPLE 10

  This example shows that nitric acid can be used for the preparation of the products of the present invention. 19.3 ml of concentrated HN0 3 were diluted to 225 ml, and 75 g of metakaolin (calcined for 50 minutes) were prepared. at 871 ° C) Three samples of the mixture were reacted in separate teflon bottles for 4.6 and 8 hours at 100 ° C. The results, shown in Table IV, show that the product with a high surface area

  after about 6 hours (samples 2 and 3).

TABLE IV

  Reaction of metakaolin with diluted HNO

  Sample N Aging time Supercritical area

hot (h) cielleamn 2

1 4 118

2 6,236

3 8 314

O EXAMPLE 11

  This example shows that selected calcination conditions reduce the reaction time required to obtain high surface area products. Separate samples of kaolin were placed in a hot oven at temperatures between 650 and 927 C for 1 hour. 50 g of each of the above calcined clays were slurried in ml of H containing 16.9 ml of concentrated HCl. The 50 g samples were divided into three separate samples and reacted in bottles. Teflon during

  4.8 or 16 hours The results, given in Table V, -

  indicate that the most effective temperature of calcination

  is 850 to 875 C Clays calcined at 927 ° C

  had a much lower reactivity.

TABLE V

  Surface area of the product as a function of the calcination temperature and the duration of the reaction. Calcination temperature (OC). Duration of the reaction, 4 hrs.

87 31

18

24 47

  1 All calcined kaolin 1 hour at the indicated temperature.

ro% A w Co n- 899, 9 a 7 -

EXAMPLE 12

  This example shows that low levels of acid can be used to obtain the product of the invention. 225 g of calcined kaolin (calcined for half an hour at 899 ° C., 1 hour at 87 ° C. or 1 hour) were slurried. to 8430 C) in a 675 ml solution containing 19.2 ml concentrated HCl. The resulting slurries were boiled at 16 hours under reflux. Each slurry sample was filtered, washed to remove Cl and oven dried. , given in Table IV, indicate a significant increase in surface area

  even at this relatively low level of acid.

The use of

TABLE VI

  HCl stoichiometric at 1:24 on various metakaolins Clay calcination conditions Reaction time (h) Superficial area (m / g) 1/2 h at 8990 C il i il i h i h h at 843 WC il il ili he i, I h to 8710 C i, t, he f I If fi a 'wc' '

EXAMPLE 13

  This example shows that a salt which can produce H + by hydrolysis can be used in place of the mineral acids. Portions of 75 g of metakaolin (calcined for half an hour at 90,000 C) were added to 900 ml solutions containing The slurries were refluxed, pH adjusted to 7.0 with 14% NH 4 OH, filtered, washed to remove Cl and oven dried. , given in Table VII, clearly show the development of materials with a very high surface area even at low levels of AM Cl 3 * 6H 20

TABLE VII

  Effect of Al C 13 6 H 20 level on surface growth rate g Al C 13 6 H 20/75 g metakaolin Reflux time (h) 1/2, 3 37.7 37.7, 1, 1 18.9 18.9 12.6 12.6 Surface area (m / g) 2 OC w oe -4% A

EXAMPLE 14

  This example shows that the ammoniation of the clay slurry having reacted with the acid just before filtration improves the activity. A reacted clay slurry was prepared and reacted as in Example 1 at except that after reaction, the p H of the slurry has

  was adjusted to 6.0 with 14% NH 40 H before filtration.

  The surface area was 326 m 2 / g and the activity was 49.2, which is significantly larger than the value

  of 40.7 observed for the product obtained in Example 1.

EXAMPLE 15

  This example shows that a better activity can be obtained by precipitation of the alumina in the presence of metakaolin reacted with the acid. It was diluted 5 400 ml concentrated HC 1 to about 48 1 with water and added 16,000 metakaolin (calcined for 1 hour at 732 ° C.) The resulting mixture was reacted under reflux for 48 hours, filtered, washed twice with 37.85 liters of H 2 O 2.

  hot This product had a surface area of 283 m / g.

  50 g (dry basis, 104.2 g as such Y) of this filter cake were dispersed in 1/2 l of H 2 O containing 26.3 g of Al C 13 6 H 20. The pH was adjusted to 6 E With 14% NH 4 H to precipitate the alumina and the product was filtered, washed twice with 1/2 L HG, deanda and dried at 120 ° C. The alumina-treated sample would have an activity 48.6 to 36.1 for the sample, treated no.

EXAMPLE 16

  This example shows the preparation of a gelled acid-treated metakaolin according to the invention. 150 g of calcined kaolin clay were added for half an hour at 900 ° C., to 1.0 liter of a solution containing, 7 ml of HCl at 37% Half of the slurry boiled under reflux for 4 hours and the other half was boiled for 8 hours Both samples were rapidly cooled, the pH adjusted to 6.0 with NH 4 OH at 14% to gel the alumina components, the slurry was filtered and washed twice with half a liter of hot, deionized H 2 and oven dried The surface areas of the samples refluxed for 4 and 8 hours were 295 and 402-m 2 / g The catalytic activity of the samples refluxed for 4 and 8 hours was 46.4 and 50.5 respectively following

  the process of the American standard ASTM D 3907.

EXAMPLE 17

  This example shows that a significant improvement in activity is observed by addition of boehmite to the acid-treated and gelled metakaolin of the present invention. 200 g of calcined kaolin clay were added for half an hour at 9000 C, To 2.0 liters of a solution containing 67.9 ml of 37% HCl and boiled under reflux for 24 hours to four cooled samples separated from the above slurry, varying amounts of boehmite were added. and the pH was adjusted to 7.0 with 14% NH 4 H, the slurry was filtered and the filter cake was washed twice with half a liter of hot, deionized H 2. The samples were dried and the catalytic cracking activity of each sample was determined The activity data, summarized in Table VII, show that the addition of boehmite to the gelled acid-treated metakaolin results in

  significant improvement in activity.

TABLE VIII

  Effect of addition of boehmite on metakaolin catalysts reacted with gelled acid% boehmite added% conversion to volume, 0 (typical), 0 59.9 17.5, 0 22.5, 0 D 59.0 59.3 1 ASTM-D 3907% volume conversion measured at 499 ° C, space velocity by weight, 16.3 C / 0 at the end of a 100% steam treatment, 8 hours, 7320 C w I

O 22

EXAMPLE 18

  Samples of a hydrothermally acid-treated metakaolin were prepared by adding 25 g of kaolin (calcined for one half hour at 900 ° C) to 125 ml of H containing 8.5 ml of 37% HCl and heated to the time / temperature shown in Table IX in teflon-coated high-pressure reactors The slurries were cooled, diluted with water to produce a stirrable slurry, the pH was adjusted to 7.0 with 14% NH 40 H, filtered, washed twice with half a liter of hot H.sub.2 and dried in the oven at 120 ° C. The activity of the hydrothermally acid-treated metakaolin is considerably increased compared to the sample.

refluxed at 100 C.

TABLE IX

  Effect of acid treatment at high temperature Reaction temperature Reaction time Surface area Activity 2 (C) (h) (m 2 / g) (% agreed volume) (typical) 4-24 400 50 (typical)

1 '40 6 413 57.9

88,526 59.2

6,392,58.0

  1 Surface area measured after a one-hour heat treatment at 593 C 2 ASTM-D 3907, percentage conversion measured after treatment, at 100% steam, 8 hours, 732 ° C. examples above clearly indicate that valuable catalytic compositions can be obtained using the teachings

of the present invention.

o

Claims (17)

R E V E N D I C A T IO N S   A catalytic composition comprising a metakaolin reacted with the acid, characterized in that it is obtained by heating kaolin at a temperature of 700 to 910 C for a time greater than about a quarter of an hour to obtain metakaolin, and subsequently reacting said metakaolin with sufficient aide-selected from the group consisting of hydrochloric, nitric, salts and mixtures thereof to react with up to about 25 mole percent of the alumina present in said metakaolin.   2. Composition according to claim 19 characterized   in that the acid is reacted with from 5 to 15 mole% alumina in the metakaolin.   Composition according to Claim 1,   characterized in that the reacted alumina is precipitated.   4. Composition according to any one of   Claims 1 or 2, characterized in that it is washed   and spray dried to obtain a catalyst of fluid catalytic cracking.   5. Composition according to claim 4, characterized in that it is mixed with a catalyst   fluid cracking composition containing a zeolite.   6. Composition according to claim 5, characterized in that the zeolite-containing catalyst comprises a zeolite selected from the group consisting of zeolite of type X, Y and ZSM in dispersion.   in a matrix of an inorganic oxide.   7. Composition according to claim 5, characterized in that the zeolite catalyst forms 10   at 90% by weight of said composition.   8. Composition according to claim 1, characterized in that it contains particulate alumina. 9 Composition according to Claim 3, characterized in that the abovementioned alumina is precipitated 4 by the addition of a base.   10. Composition according to claim 9,   characterized in that the aforesaid base is ammonia.   11 Process for preparing the catalytic composition   according to one of claims 1 to 10, characterized   what it consists of: (a) calcining kaolin at a temperature of 700 to 910 WC for more than about a quarter of an hour to obtain metakaolin; (b) reacting said metakaolin with sufficient acid to react with up to 25 mole percent of the alumina present; and   (c) forming the mixture into catalyst particles.   12. Process according to claim 11, characterized in that the product obtained in step (b) is reacted with a base to precipitate the soluble components of alumina before step (c). Process according to claim 11 or 12, characterized in that the aforementioned acid is selected from the group consisting of   hydrochloric and nitric acids and their salts.   Process according to claim 11, characterized in that the above mixture is formed by spray drying   extrusion, pellet shaping or granulation.   15. The method of claim 11, characterized in that the aforementioned particles of the catalyst are heated to 300 to 800 WC.   16. Process according to claim 11, characterized in that the aforementioned Kaolin is calcined in step (a) for approximately a quarter of an hour at 8 o'clock.   17. A method of cracking-hydrocarbons, characterized in that it consists in reacting a hydrocarbon feedstock with the catalyst according to any one of   Claims 4, 5, 6 or 7 under catalytic cracking conditions.