DE1193484B - Process for the production of a silicon dioxide-aluminum oxide catalyst suitable for fluidized bed cracking processes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

Number:
File number:
Registration date:
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BOIj

German class: 12 g -4/01

1193 484
N16599 IV a / 12 y
April 22, 1959
May 26, 1965

The invention relates to a method for producing a catalyst for the cracking of petroleum hydrocarbons, that by coprecipitation in an aqueous medium of a hydrated silica and a siliceous inorganic additive having an average particle size of not more than 20 μ obtained with intimate connection of the two components kind, then a hydrated aluminum oxide is precipitated on the mixture obtained and the product is spray-dried will. In particular, the invention relates to the use of both synthetic silica-alumina compositions as well as naturally sourced silica-alumina compositions in the manufacture of the new, high-performance catalytic converters.

The use of such or similar synthetic silica-alumina compositions as Cracking catalysts are known per se. Certain types of clays, e.g. B. Acid activated montmorillonite have also been used as catalysts for cracking petroleum hydrocarbons.

The well-known silica-alumina catalysts leave when they are used for fluidized bed cracking processes in spite of their good catalytic effect but much to be desired due to physical and mechanical defects.

In the fluidized bed cracking process, the catalyst particles conveniently come in microscopic form small balls for use, the preferred particle size of which is between 20 and 120 μ amounts to. Since the catalyst particles are kept in a fluidized state, the through friction caused by movement poses a serious mechanical strength problem. Synthetic microscopic small spheres of silica and aluminum oxide have been used for fluidized bed cracking proved to be particularly suitable. However, they are extremely hard and about as brittle as glass, like that that these catalyst particles easily break into even smaller particles with the incessant movement that occurs during Fluidized bed process prevails, disintegrate. Extremely fine particles formed in this way often go with it lost in the exhaust gases and this loss must be replaced by adding fresh catalyst.

The catalysts derived from natural sources have an economic advantage because the Raw material is cheaper in this case. However, these natural raw materials leave in the manufacture microscopically fine beads suitable for use in fluid bed cracking to be desired. Also are their own physical processes for producing one for fluidized bed cracking processes suitable silica-alumina catalyst

Applicant:

Nalco Chemical Company, Chicago, JIl.

(V. St. A.)

Representative:

Dipl.-Ing. E. Prince and Dr. rer. nat. G. Hauser,

Patent attorneys,

Munich-Pasing, Ernsbergerstr. 19th

Named as inventor:
David Gordon Braithmaite, Chicago, JH .;
Edwin Herald McGrew, Riverside, JIL;
William Peter Hettinger Jr., Dolton, JIL;
Joseph Santi d'Amico. Westchester, JIl.
(V. St. A.)

do not always create what you want, not even for Fixed layer catalytic processes. The invention now provides a method of manufacture new fluidized-bed cracking catalysts of the type defined at the outset, which are extremely mechanically are resistant and suffer lower losses through attrition than those previously available standing synthetic silica-alumina catalysts.

The invention is characterized in that the silicic acid-containing additive material is 20 to 85 percent by weight of hexagonal kaolinite, preferably 30 to percent by weight, in particular 50 percent by weight, (based on the total solids content of the catalyst), of which at least 10 percent by weight has a size of 1 μ or less and most one Particle size between 0.1 and 20 μ and which does not _{contain more than 2% Fe (calculated as Fe 2} O ₃ ) is used.

The end products obtained according to the invention consist essentially of silica and alumina, made up of microscopic spherical particles of silica and alumina, which are both of synthetic as well as natural origin.

The kaolinitic clay used in the practice of the invention contains about 2 moles of SiO ₂ per mole

509 577/411

Al ₂ O ₃ . It has a crystalline planar and hexagonal structure. The particles are relatively thin; their thickness is usually less than a tenth of the longest dimension.

Kaolinites of this type are particularly found in Georgia and more arid parts of the United States States. The kaolinite crystals to be used according to the invention are obtained by customary methods, where z. B. mixed with water, a polyphosphate such as sodium hexametaphosphate is added to to keep the clay in suspension, then the quartz is sieved out, centrifuged, with sulfuric acid z. B. at a pH of 3.5 washed out, bleached and with small amounts of various flocculants, z. B. alum, flocculated, filtered off, dried and ground. In natural tones, e.g. B. Ilmenite are often contain iron and titanium, much of which is removed during centrifugation.

The clays used to carry out the invention suitably have a high degree of purity. The presence of iron in a catalyst promotes hydrogen formation during cracking, and when the iron content of the clay exceeds about 2 percent by weight, it is expedient to leach the clay prior to its use according to the invention with an inorganic acid.

In addition to the iron content lying within the specified limits, the clay contains at least 10 percent by weight of particles of colloidal fineness. The greater the percentage of colloidal Particle is in a particular kaolinite, the more suitable it is for making a catalyst. Finely divided clays can be fractionated using known sedimentation techniques can be obtained. Although clay with a colloidal degree of fineness is preferred, clays have also turned out to be with larger amounts of particles over 5 μ in size have been found to be suitable for carrying out the invention.

Kaolinites are usually according to particle size ranges, for. B. by centrifugation, air flotation or withdrawal methods, separately. For example, two types of kaolinite available on the market contain 10 percent by weight Particles smaller than 0.2 μ, 50 percent by weight smaller than 0.6 μ and 90 percent by weight smaller than 1.6 μ, or about 10 percent by weight of particles smaller than 0.6 μ, 50 percent by weight smaller than 5.2 μ and 90 percent by weight smaller than 20 μ and are referred to as "Premax" or "Hydrite".

The silica-aluminum oxide composition should contain 55 to 95 percent by weight of silica (SiO ₂ ) and 5 to 45 percent by weight of alumina (Al ₂ O ₃ ).

For the production of the synthetic silica-alumina composition various methods can be used. A typical procedure is that of an alkali metal silicate gelled with an inorganic acid while maintaining an alkaline pH. Then you mix with the silica hydrogel an aqueous solution of an acidic aluminum salt, so that the aluminum salt solution fills the pores of the silica hydrogel. The aluminum is then in the form of hydrous Aluminum oxide precipitated by adding an alkaline compound. Case in point of this Method is the preparation of a silica hydrogel described below:

A sodium silicate solution is added with vigorous stirring and at controlled temperature and temperature Concentration conditions with sulfuric acid or hydrochloric acid. Then you add the silica hydrogel vigorous stirring to a solution of aluminum sulfate or aluminum chloride in water, so that the Aluminum salt solution fills the pores of the gel, whereupon the gel is agitated vigorously Precipitation of aluminum in the form of hydrous aluminum oxide in the pores of the silica hydrogel mixed with aqueous ammonia, whereupon z. B. some of the water on vacuum filters

ίο separates from the gel and then dries it, and by spray drying. The dried product is then used to remove sodium and sulfate ions washed out either with water or with a very weak acid solution, whereupon the obtained Product down to a low moisture content, usually less than 25 percent by weight, z. B. from 10 to 20 percent by weight, with achievement the finished catalyst is dried.

In another procedure, the silica is made from an aqueous alkali metal silicate solution by adding an aqueous acid solution, preferably an aqueous solution of a mineral acid, ζ. Β. Sulfuric acid or hydrochloric acid precipitated, the concentration of the acid being so low that local Reactions and a greater development of heat during the addition of the aqueous acid solution avoided will. The amount of the aqueous acid added to the alkaline aqueous silicate solution is sufficient to precipitate the silica as a hydrogel and to lower the pH of the solution obtained, preferably to an alkaline value (about pH 8 to 10.5), although the pH value may also down to about 5.

The hydrogel is then treated with an aqueous solution of an alkaline aluminum salt in which the aluminum is present as an anion, e.g. B. a solution of sodium aluminate, potassium aluminate or calcium aluminate, whereby the pH is slightly increased and the aluminum is precipitated in the form of aqueous aluminum hydroxide. The gel slurry is then added to an acidic aqueous solution of an aluminum salt in which the aluminum is only present as a cation, e.g. B. a solution of aluminum chloride or preferably aluminum sulfate, whereby the pH of the slurry is preferably lowered to a value of 4.5-5. In this process stage, the silica hydrogel is impregnated with further amounts of aluminum oxide in a water-containing form. The concentration of the aqueous solution of the aluminum salt mentioned, in which aluminum is present as a cation, is expediently adjusted so that the weight ratio of water to the salt, expressed as Na ₂ Al ₂ O ₄ , is at least 7.5: 1 and preferably 15: 1 or more. The volume dilution of the sodium, potassium or calcium aluminate solution is usually at least 5: 1 and preferably about 10: 1. More dilute solutions can also be used, but do not improve the products obtained significantly, but tend to have additional problems relating to the separation of the To create water from the end product. Although catalysts obtained using a relatively concentrated aluminum salt solution are useful, it has been found in practice that alumina precipitated from a concentrated aluminum salt solution is not the same as that precipitated from more dilute aluminum salt solutions, and that using

5 6

to determine the effect obtained with dilute aluminum salt solutions. The general weight compositions as catalysts for the catalytic ratio of clay to hydrogel is preferably Process, particularly for catalytic cracking 1: 4 to 4: 1, and the optimum range is between

of petroleum hydrocarbons are more suitable. 1: 1 and 2: 1.

The hydrogel silica slurry containing the alumina in hydrous form 5 Typical Synthetic Silica-Alumina Containing compositions which were then tested for the invention to increase the total solids content are (1) a total of over 8% by weight of the composition filtered. The filtration can in some cases optionally be carried out through 13 percent by weight aluminum oxide and 87 percent by weight, but is important if you contain 10 percent silica, and (2) a small aluminum-microscopic bead with a composition rich in particles, which 25 weight size between 20 and 100 μ wants to obtain, which contains one percent Al ₂ O ₃ and 75 percent by weight SiO ₂ , particle size favorable for fluidized bed catalysts, these compositions are based on the above. The filtration also effects a largely described manner with a natural kaolinite clay cleaning the gel by removing dissolved salts combined, so both result in extremely effective catalysts, and promotes the formation of a continuous catalyst. Particularly good results were obtained when the alumina-rich composition was finally obtained microscopically on the small spherical particles. After filtration in the manner described above with the clay in approximately slurry, the filter cake is combined with a spray of equal parts by weight,
exposed to drying by first using as much water as 20

that a pumpable mixture is obtained, again Example 1
is slurried. The spray-dried product

is then washed out and applied to the above

given way finally dried. Water and 1374 kg Snowbrite clay, which is 86.0%

The foregoing contained a relatively detailed 25 solids, mixed, and slurry

Description of two methods is given, in which heating was carried out with a heating coil for 30 minutes.

Aluminum oxide in water-containing form on a silica gel 193 l was added to the heated slurry

incorporated and the gel obtained then to obtain sulfuric acid (354 kg) of 66 ⁰ Be. The added one

microscopic spheres, which corresponded to the amount of cataly- ic acid, 0.14 kg of acid per kilogram

table processes are suitable for further treatment. In 30 tones. When the acid addition was complete, the mixture became

In each case, the relative proportions should be cooked for 75 minutes, the temperature of one

Silica to aluminum oxide between 55 and starting temperature of 32.2 ⁰ C to a final

95 percent by weight silica and 4 to 45 Ge temperature of 6I ⁰ C rose,

weight percent aluminum oxide, on a dry basis.

amount, d. H. without taking into account the in the gel- 35 mung with more water and mixed the material

structure of silica and aluminum oxide thoroughly. The loading was with a

contained water. The temperature of the reaction- small amount of a coagulant added, and

Mixture is subject to fluctuations, but the clay was left to settle. The liquid became clear

Appropriately siphoned off at each of the individual process steps, and the container was again filled with water

between about 4 and 6O ⁰ C. 40 filled. This water was then also siphoned off.

A preferred method of introducing the sample of the two decanting liquids has been made

Kaolinite clay in the synthetic silica-alumina - tested for its own content. 0.005 g was found

Compositions consists in first adding iron per liter in the liquid siphoned off first

the clay in the silicate solution before the formation of the silica and 0.001 g of iron per liter in which the second time

hydrogels intimately dispersed or peptized. Another 45 siphoned liquid.

Method for combining the clay with the The washed slurry was mixed with 21771 synthetic silica-alumina hydrogel in a _{sodium silicate solution containing 28.6% SiO 2 of} an intimate mixture of the peptized clay. This solution was mixed well with the clay slurry with a preformed silica slurry, and the clay-hydrogel mixture was heated. The sodium silicate acts as a 50 to 32.2 ° C, whereupon 7651 35% admitted ig ^e r sulfuric acid peptizing agent and dispersed within the flat kaolinite in 37 minutes. Crystals 33 minutes after addition. When the silica hydrogel precipitated, the acid gelation occurred. Then these crystals were then given evenly in the approximately 14441 alum solution (7.8% Al ₂ O ₃ ) composition distributed within half 20 minutes. Since kaolinite is about the same, followed by 3791 _{atomic fractions of silicon (Si) and aluminum (Al) containing 23.6% Al 2} O ₃ , 55 sodium aluminate solution, the addition of which contains within, the ratio of silicon and aluminum is 8 Va minutes. During the same 8% of the clay content of the catalyst, about Si-Al-Si-Al grooves are diluted at a rate of, etc., and this ratio becomes 151 l per minute with water even after formation. The ultimate charge possessed of the silica and after impregnation of at 30 ⁰ C a pH of 5.3.
The silica hydrogel with the alumina hydrogel was then pumped out of the reaction vessel as electron photomicrography vessels point and on drum filters. filtered. The filter cake obtained had a

When microscopic particles produced solid content of 18.28% · He was then in one

are to be, these tend to be more generally more hot air stream spray-dried. The size of the

to be ground when the amount of clay, 65 nozzles of the spray dryer was 2.5 and 3.1 mm, respectively,

based on the weight of the total collapse and the nozzle pressure was 176 and 141 kg / cm ^2, respectively. the

settlement, exceeds 75%. Are less than 20 Ge temperature of the exiting from the spray dryer

weight percent clay is added, so is practically no solids was 88 ⁰ C. The sprayed

7 8

Dried, microscopic globules were mesh size, and on average went down

then sifted. 2% of this did not pass through a sieve, 19% of the solids passed through a 0.12 mm sieve with 0.074 mm clear mesh size through, and 66% mesh size through.

passed through a 0.12 mm mesh sieve. The spray dried microscopic cows passed through. 5 gels were then washed out with spray-dried, microscopic kills of sulfuric acid, aqueous ammonia and gels were then cleaned with sulfuric acid solution (about water. The average of three determinations of 1.4 g of H ₂ SO ₄ per liter of aqueous solution ) to remove the sodium sulfate content in the wash water from sodium ions and then with aqueous ammonia gave: Na ₂ O == 0.007%, SO ₄ ² = 0.84%.
washed to remove the sulfate ions. Then the washed microscopic beads, the solids were washed out with water. They were then dried very quickly. The temperature average of eleven determinations of the sodium or the solids sulphate content emerging from the high-speed dryer gave Na ₂ O = 0.012%, SO ₄ = 0.51%. was 121 ° C and its moisture content was 23.6%. The leached solids were then quickly dried. The aluminum content of the catalyst calculated. The temperature of the solids emerging from the fast 15 on a dry basis and expressed as Al ₂ O ₃ , drier was 149 ^° C. was 47.0%, its sodium content, expressed as The catalyst possessed, on a dry basis, a Na ₂ O 0.38% ^sem SO ₄ ² content 1.1% ^UI * d its aluminum _{content, expressed as Al 2} O ₃ , of 37.2%, iron content 0.43%. The remainder was essentially SiO ₂ . 0.043% Na, expressed as Na ₂ O, an SO ₄ ² content. The surface area of the catalyst was 261 m ² / g, from 0.4% and 0.41% iron. The remainder was essentially its pore volume 0.62 cm ³ / G and its pore permeable SiO ₂ . The surface of the catalyst was 95 Å.
234 m ² / g, the pore volume 0.59 ccm ³ / g and the. .
Pore diameter 102Ä. In its evaluation as an example 3
In another batch, the procedure was repeated according to a density of 0.43 g / cm ^s and a bulk density according to a steam treatment under a pressure of 4.2 kg / cm ^{2 with equal proportions of the ingredients} , but the amount of clay used is 0.49 g / cm *. calculated to have a 75% clay contained in the previous example containing the synthetic holding catalyst.

silica-alumina composition prepared The catalyst had, calculated on a dry basis, about 75 percent by weight SiO ₂ and 25 percent by weight, an aluminum _{content expressed as Al 2} O ₃ , percent Al ₂ O ₃ . The weight ratio of the clay to 37.7%> it contained 0.067% Na, expressed as the synthetic silica-alumina composite Na ₂ O, about 0.1% SO ₄ ² and 0.67% Fe. The rest of the settlement was about 1: 1. The spray obtained is essentially SiO ₂ . The initial bulk density of dried microscopic spheres possessed was 0.56 g / cm ³ , and the bulk density after satisfactory properties, while the clay 35 directing steam under a pressure of 4.2 kg / cm ² alone to form acceptable microscopic was 0, 58 g / cm ³ ,
small beads cannot be spray dried.

Example 2 Example 4

In a batch process, 220 kg 40 were used.

Explain "Snowbrite" clay (0.87% Fe) with a solid sator, in which the ratio of synthetic

content of 86.0% with 17601 32.2 ° C hot water table silica to synthetic aluminum oxide

offset. The mixture was then stirred to give about 87:13. 4.1kg "Nowbrite" kaolinite

a uniform slurry of clay. were suspended in 37.9 l of water. One mixed

This slurry was mixed with 34831 45 7.61 sodium silicate solution containing 28.6% SiO ₂ ,

Sodium silicate solution containing 28.6% SiO ₂ . That within 1 hour at a temperature of about

Material was mixed well and heated to 32 ° C 32 ° C with the clay. Then they gave 2.71 of a 35% strength

heated, whereupon 12261 35% sulfuric acid sulfuric acid together with 2.41 of a 7.8% Al ₂ O ₃

admitted within 50 minutes. The mixture gelled containing alum solution within 35 minutes.

after 37 minutes. 50 It mixed 0.6251 of one containing 23.6% Al ₂ O ₃

Sodium aluminate solution with a further 2.5 liters of water was added to the gel within 35 minutes.

23091 aluminum sulfate solution (7.8% Al ₂ O ₃ ) under The sodium aluminate solution was the previously prepared

simultaneous mixing. With continued mixing until a final pH

Mixing was added 7191 sodium aluminate solution value from 5.5 to 6.0 and the resulting

(23.6% Al ₂ O ₃ ) within 19 minutes. During 55 composition, as in Example 1, for

at the same time, one diluted further with water to obtain microscopic spheres.

Speed of 1511 per minute. The final treats.

Charge had a pH of 5.3 and a _D. . , <-

Temperature of 38 ° C. Example 5

The material was then filtered on a drum filter 60. The procedure was the same as in Example 2. The solids content of the filter cake was only 19.0% instead of the “Snowbrite” kaolinite clay. The filter cake was then used in a sprayed “Hydrite” clay. The catalyst contained, drier with a nozzle size of 3.1 mm spray- calculated on a dry basis, 31.1% Al ₂ O ₃ , 0.045% dried. The Versprühungsdruck ranged from Na ₂ O, less than 0.20% F ^e> calculated as Fe ₂ O _3, 13.4 and 13.7 kg / cm ^2. The outlet temperature of the 65 was less than 0.1% SO ₄ , and otherwise it consisted of dried solids was 88 ° C. On the average, essentially composed of SiO ₂ . The initial volume passed 50% of the spray dried microscopic activity was 67 and 44 after passing small beads not through a sieve with 0.074 mm steam. The initial weight activity was 58

and after passage of steam 36. The bulk density before passage of steam and 0.61 thereafter.

One method of evaluating cracking catalysts is by determining the relative "activity" of the catalyst. So z. B. for determining the activity, a Midcontinent Gas oil fraction having an API gravity of 32.3 °, an initial boiling point of 280 ⁰ C and a final boiling point of 390 ⁰ C, with a sulfur content of 0.35% at atmospheric pressure and 482 ° C passed over a solid layer of the catalyst contained in an oven at a space velocity of about 4 volumes of gas oil per volume of catalyst per hour (4 VHSV). The liquid hydrocarbon product is then fractionated, and the ^{portion boiling below 204 0} C is condensed in a suitable container and represents the gasoline fraction. A sample of a standard catalyst (volume activity 100) is at 2, 4 and 8 VHSV for conversion into gas and gasoline in Put into operation. These conversions are plotted in curves as a function of the reciprocal space velocity, so that a standard calibration curve is obtained. Each point on this curve means a volume activity of 100. All unknown samples are put into operation at 4 VHSV under the conditions described above. The volume activity of these unknown samples is one hundred times the ratio of the space velocities of the unknown sample and the standard sample required to achieve the same degrees of conversion. From the data relating to the unknown samples, the calibration curve and the bulk density, both the volume activity and the weight activity of the unknown samples can easily be calculated.

If the catalyst has not been pretreated, the activity is usually referred to as the "initial activity". The catalyst by 16 hour steam treatment at a steam pressure of 4.2 kg / cm ² was treated at 649 ⁰ C, the activity is referred to as "activity after steaming." Typically, the initial activity for any catalyst will be higher than the activity after steaming. However, the activity after steaming is of more practical importance in evaluating the catalyst. The division of the products obtained is also a factor in determining the value of the catalyst.

The catalyst of Example 1 had an initial volume activity of 63, an initial weight activity of 73, a volume activity after steaming of 44, and a weight activity after steaming 45. The bulk density of the catalyst was before steaming 0.43 and after steam treatment 0.49.

The catalyst prepared according to Example 2 had an initial volume activity of 89.5 and a Weight activity of 78. The volume activity after steaming was 45 and the weight activity after steaming was 37.1. the The bulk density of the catalyst was 0.58 before steaming and 0.61 afterwards.

The catalyst of Example 3 had an initial volume activity of 47 and a volume activity after the steaming of 45. Its weight activity before the steaming was 41 and after 30. The bulk density before steaming was 0.56 and after steaming was 0.58. The initial volume activity of the catalyst of Example 4 was 66, and the volume activity after the steam treatment was 36. Its initial weight activity was 51 and its weight activity after steaming was 28. The bulk density was 0.64 before steaming and 0.66 afterwards. These results show that all of these catalysts have been used successfully for catalytic cracking can be.

The following table shows the breakdown of from a midcontinent gas oil of those described above Art obtained products, the gas oil gas for 15 minutes at atmospheric pressure and 482 ° C, achieving various degrees of conversion, continuously in the circuit over the catalysts of Example 1 and 2 was performed.

Example I *

catalyst
Example II Example II * 31.8% 60.6% 99.2% 96.5% 25.1 117 117
2.95% 366
7.25% 8.55%
5.76% 10.4%
7.03% 26.2%
22.9%
U% 47.0%
42.5%
3.04% 509 577/411

1. Implementation

2. Total Recovered Product

3. H ₂ , feet »/ barrd of oil

4. C ₃ fraction, gas

(a) CF / bbl. oil

(b) weight basis

5. C ₄ fraction

(a) Volume base

(b) weight basis

6. Gasoline fraction

(a) Volume base

(b) weight basis

7. Coke, weight basis

37.9%
98.5%
46.3

193
4.79%

10.2%
6,857 _O

29.2%
23.47 _O

0.927ο

* Catalyst treated with steam under a pressure of 4.2 kg / cm ^2.

The conversion value results from the difference between the weight of the oil used minus the weight of the material in circulation, divided by the weight of the oil charge times 100, if the material in circulation is the fraction with a boiling point above 204 ° C. The C ₃ fraction is a fraction of gases with 3 carbon atoms and lighter gases and includes e.g. B. propane, propylene, ethane, ethylene, methane, etc. The C ₄ fraction includes the hydrocarbons with 4 carbons z. B. η-butane, isobutane, butylene, etc. and is measured on a volume basis in liquefied form. The gasoline range includes hydrocarbons with 5 carbon atoms up to hydrocarbons with boiling points up to 204 ^° C.

In the examples above, the "Snowbrite" clay was a Georgia kaolinite which, on a dry basis, contained about 37.2% Al ₂ O ₃ , 0.43% by weight Na ₂ O, 0.4% by weight SO ₄ , 0.41% by weight Fe and otherwise contained _{SiO 2.} Another particularly suitable clay has a similar chemical composition and crystal structure. Its particle size is such that 10 percent by weight less than 0.26 μ, 30 percent by weight less than 0.5 μ, 50 percent by weight less than 0.9 μ, 80 percent by weight less than 2 μ, 90 percent by weight less than 3.5 μ and 95 Weight percent are less than 4.5 μ.

In connection with the table showing the product distribution, it should be noted that different degrees of conversion are of course achieved when changing the space velocities (volume of gas oil to weight of the catalyst). So was z. B. achieved the degree of conversion of 37.9% with 150 cm ^{3 of} gas oil per 250 g of catalyst; the degree of conversion of 31.8% was achieved with 150 cm ^{s of} gas oil per 200 g of the catalyst containing 16% moisture (168 g on a dry basis); and the degree of conversion of 60.6% was achieved with 475 g of catalyst. All experiments were carried out at 482 ° C. for 15 minutes.

The catalysts obtained according to the present invention have satisfactory activities and are more economical manufactured as synthetic silica-alumina catalysts. It was impossible to predict that such large amounts of kaolinite of the synthetic silica-alumina composition while maintaining a satisfactory catalytic effect could be added. Within certain, limits given above, a kaolinite of the type indicated also improves the friction resistance of microscopic spheres from the compositions according to the invention. Furthermore, the microscopic beads can pass through Spray drying can be obtained, which is a great advantage of synthetic catalysts, that of natural Catalysts originating from sources usually do not adhere. The invention provides catalysts with very good stability.

Claims (2)

Patent claims: 1. A process for the production of a silicon dioxide-aluminum oxide catalyst suitable for fluidized bed cracking processes, in which a hydrated silicon dioxide and a silicic acid-containing, inorganic additive material with an average particle size of not more than 20 μ are intimately connected to one another, a hydrated aluminum oxide precipitated onto this mixture and the product is spray-dried, characterized in that 20 to 85 percent by weight of hexagonal kaolinite (based on the total solids content of the catalyst), of which at least 10 percent by weight has a size of 1 μ or less and most a particle size between 0 , 1 and 20 μ and which does not _{contain more than 2% Fe (calculated as Fe 2} O ₃ ) is used. 2. The method according to claim 1, characterized in that a naturally occurring kaolinite is used, which is suspended in water, freed from quartz by sieving, centrifuged, Washed out with sulfuric acid, bleached, flocculated, filtered off, dried and ground became. Considered publications: German Patent Nos. 742196, 752 698, 494, 884 189, 1023 015;
German Auslegeschrift No. 1 110 351;
French Patent No. 916 755;
British Patent Nos. 498 094, 724 567; U.S. Patent Nos. 2,763,622, 2,768,145. Legacy Patents Considered:
German Patent No. 1 144 860. 509 577/411 5.65 © Bundesdruckerei Berlin