DK144873B - PROCEDURE FOR THE PREPARATION OF A CARBON HYDRADE CRACKING CATALYST CONTAINING A CLAY-SOILED SYNTHETIC SILICON OXIDE / MAGNESIUM OXIDE - Google Patents

Description

(19) DENMARK \ | ^)

^ (12) PUBLICATION WRITE OR U4873B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. 3980/73 (51) lnt.CI.3 B 01 J 21/16 (22) Filing date 18 Jul. 1973 (24) Race day 18 Jul. 1973 (41) Aim. available Jan 20 1974 (44) Submitted 28 Jun. 1982 (86) International application # - (86) International filing day (85) Continuation day - (62) Master application no -

(30) Priority 19 Jul. 1972, 273147, US

(71) Applicant W.R. GRACE & CO., New York, US.

(72) Inventor Richard William Baker, US.

(74) Associate Engineering Company Budde, Schou & Co.

(54) Process for preparing a hydrocarbon cracking catalyst comprising a clay = soil containing synthetic silica = oxide / magnesium oxide.

The present invention relates to a process for preparing catalysts for use in cracking hydrocarbons and in particular to semi-synthetic cracking catalysts based on silica / magnesium oxide and having both a high efficiency and a desirable low equilibrium surface area. q Silica / magnesium oxide and silica / magnesium oxide / - ^ fluoride materials can be used as catalysts in cracking ^ + hydrocarbons, exhibiting high cracking activity, good C, ben-0 ^ z zine selectivity and, in addition, providing exceptionally high yields of light + _ circulating oils.

Although conventional catalysts based on silica / magnesium oxide exhibit several desirable properties, these catalysts are generally made with a high equilibrium surface area, usually about 300-400 m / g. As a rule, a large surface area is desirable because it is associated with high activity. However, a large surface area makes it difficult to liberate the hydrocarbon catalyst after a cracking cycle, and consequently large amounts of hydrocarbon are passed into the regeneration or coke firing stage, resulting in unusually high temperatures in the regenerator. Until now, the only practicable method of limiting the temperatures during the regeneration of a typical silica / magnesium oxide catalyst has been the use of quenching with spray water. On the other hand, it is often found that the use of water cooling during regeneration interferes with the coke burning operation.

Thus, it is an object of the present invention to provide silica / magnesium oxide cracking catalysts (including silicon / magnesium oxide / fluoride-based catalysts) which are likely to have high activity but which can be more easily regenerated in conventional equipment. for the treatment of hydrocarbon.

These two properties can be obtained with a hydrocarbon conversion catalyst comprising a silica / magnesium oxide (or silica / magnesium oxide / fluoride) material and a crystalline aluminum silicate zeolite prepared as described below.

Namely, it has been found that a highly active low surface area catalyst containing silica / magnesium oxide or silica / magnesium oxide / fluoride can be prepared by combining from ca. 20 to 50% by weight of clay soil with a silica / magnesium oxide or silica / magnesium oxide / fluoride material, which in turn contains approx. 60 to 92% silica, 8-40% magnesium oxide and 0 to 6% fluoride. The catalyst material may contain from ca. 0.1 to 20% by weight of a crystalline aluminum silicate zeolite, such as synthetic faujasite, and the catalyst is obtained with an initial surface area ie. in freshly prepared and yet unused condition (after heating to 538 ° C for 3 hours) of 2 from approx. 300 to 600 m / g and an equilibrium surface (after treatment with water vapor at 566 ° C for 24 hours using a vapor pressure of 4.2 ato (ie, 5.2 ata) followed by heating to 843 ° C for 2 3 hours ) of approx. 125 to 300 m / g. The pore volume 3 of the catalyst is in the range of 0.4 to 0.8 cm / g, which indicates an increase in the number of macropores and should facilitate the removal of coke.

144873

The catalyst is prepared according to the present invention by first combining an aqueous slurry of clay soil and optionally zeolite with an aqueous solution of alkali metal silicate, preferably sodium silicate, and then gelling the silicate. Suitable gelling agents which can be added to the slurry of clay soil and silicate include mineral acids and carbon dioxide. After gelation of the silicate / clay soil mixture, magnesium oxide is incorporated in the form of a hydrated slurry and fluoride is added, optionally in the form of e.g. hydrogen fluoride. The material is then filtered, washed, spray dried and washed again before final drying.

Accordingly, the invention relates specifically to a process for preparing a hydrocarbon cracking catalyst comprising a synthetic silica / magnesium oxide or silica / magnesium oxide / fluoride containing from 12 to 35% magnesium oxide and up to 4% fluoride, from about 20 to approx. 40% by weight of clay soil, and optionally a crystalline aluminum silicate zeolite, to form a catalyst with an initial surface area of about 2%. 300 to 600 m / g and an equilibrium surface area of approx. 125 to approx. 300 m / g obtained after heating to approx. 566 ° C for 24 hours under water vapor at 4.2 ato followed by heating to 843 ° C for 3 hours, which is characterized by adding clay soil to an aqueous alkali metal silicate solution to form a slurry which is acidified to gel the alkali metal silicate, and then a slurry of hydrated magnesium oxide and water is added to the gelled product and optionally hydrogen fluoride is added to the prepared mixture to produce a fluoride-containing catalyst, filtering, washing and drying, preferably adding 0.1-20 by weight of a crystalline aluminum silicate zeolite before drying.

Preferably, the process according to the invention is carried out such that the drying is carried out by spray drying.

German Patent Specification No. 1,767,754 discloses a catalyst containing a SiC 2 -MgO component, a clay soil component and optionally also a zeolitic component; but in the method known from this German disclosure another technique is used, using as starting material a silica sol to which clay soil is added and then hydrated magnesium oxide which is mixed with the clay soil / sol mixture, forming granules from the three component mixture by gelation. a water immiscible medium.

In contrast, the process of the invention is based on a sodium silicate solution to which the clay soil is added directly to form a slurry which is then gelled by acidification and then hydrated magnesium oxide is added to the gelled product.

Thus, there are three clear differences between the respective processes, namely: i) The starting material of the process according to the invention is a sodium silicate solution and not a silica sol.

ii) The gelation is carried out before and not after the addition of magnesium oxide.

(iii) The gelation is carried out by acidification and not by mixing with a water-immiscible solvent.

Thus, it is seen that the stated difference in the order of steps of the assembly of the components must depend on the particular technical effect of the invention, the provision of a catalyst material having a lower surface area than the conventional hydrocarbon cracking catalysts based on silica / magnesium oxide. This has certain advantages in connection with the use of the catalyst and in particular regeneration, as further explained below.

However, as will be apparent from the outset, the prior art silica / magnesium oxide-based catalysts suffer from significant disadvantages in that their large surface area tends to render them difficult to free from hydrocarbon after a cracking cycle. As a result, large amounts of hydrocarbon are fed or entrained via the catalyst into the regeneration cycle, where they then lead to excessively high temperatures in the regenerator. It is this problem that is solved by the present invention, where particular emphasis has now been given to providing silica / magnesium oxide-based catalysts which have the same high activity as the known silica / magnesium oxide-based catalysts, but which can be more easily regenerated in conventional carbohydrate reprocessing equipment.

These catalysts are specially prepared as above, by adding clay soil to an alkali metal silicate solution which is then gelled by acidification. As pointed out above, this process differs in essential respects from the prior art. This provides a new technical effect with respect to obtaining an equally active catalyst composition, which is, however, easier to regenerate at lower regeneration temperatures, allowing the use of conventional equipment to avoid the costly high temperature regeneration system.

In addition, there are particular advantages with respect to the preferred catalyst composition, which contains a certain amount of crystalline zeolite whose presence increases the activity of the catalyst. This is shown by comparing Example 5 (71% conversion) with Example 1 (61.5% conversion). In addition, the selectivity for providing the highly desired and valuable gasoline fraction, which is 63% compared to 55%, is increased in the examples in question.

These differences in manufacturing technique obviously have a technical advantage that could not be achieved with the known catalyst, which although contains similar components, but which is made by another technique. The German publication does not contain any indications which make this variation in the technique obvious.

The clay soil used in the process of the present invention is preferably kaolin with an average particle size of from 0.5 to 2.0 µ. In addition to kaolin, other clay soils such as bentonite, halloysite, montmorillite and attapulgite can also be used, as well as thermally or chemically treated or activated derivatives thereof. As indicated above, the clay soil component is used in the catalyst preparation of the invention in amounts ranging from approx. 20 to approx. 50% by weight based on the finished catalyst material.

The crystalline aluminum silicate zeolites, which can be incorporated into the catalyst by the process of the invention, can usually be defined as stable zeolites with pore openings of approx. 5 to 15 Angstroms. Preferred zeolites are synthetic faujasites and modified forms of synthetic faujasites with a silica / alumina ratio of approx. 2.5: 1 to 6: 1 and having thermal stability in the range of 815 ° C to 927 ° C.

Typical zeolites which may be used are calcined and exchanged with rare earth type X and type Y prepared as disclosed in U.S. Patent No. 3,420,996. Hydrogen-exchanged faujasite, which has been further treated to increase stability, such as U.S. Patent No. 3,393,192, can be used advantageously. Furthermore, faujasite exchanged with a combination of hydrogen and / or polyvalent metal ions from group III to group VIII of the periodic system can be used in the catalyst material of the process of the invention.

The silicate component of the present catalyst is generally sodium silicate, which is used in the form of a dilute aqueous solution containing from ca. 3 to approx. 6% by weight of silicate (SiO2). While the present description generally refers to the use of sodium silicate, it should be noted that other alkali metal silicates such as potassium silicate may also be used.

Usually, so much silicate is used so as to provide from ca. 40 to approx. 75% by weight SiO2 in the final catalyst composition.

The magnesium oxide (MgO) used in the preparation of the catalyst by the process of the invention is usually obtained in the calcined form. The calcined magnesium oxide is combined with water in the presence of a small amount of mineral acid, usually sulfuric acid, and thereby converted into a hydrated form. As a rule, a magnesium oxide slurry in water containing from ca. 5 to approx. 30% by weight of MgO, which is hydrated in the presence of from approx. 10 to approx. 50% by weight of sulfuric acid, suitable for preparing the catalyst by the process of the invention.

As indicated above, the catalyst may optionally contain fluoride. If fluoride is used, it is usually preferable to add the fluoride in the form of hydrogen fluoride to the gelled silica and magnesium oxide components. However, hydrogen fluoride can be added to the slurried magnesium oxide hydrate; before adding to the gelled silicate. When hydrogen fluoride is added to the magnesium oxide slurry, precipitated magnesium fluoride will usually form. Generally, it can be said that when fluoride is used in the formation of the present materials, so much fluoride is added that it is from 1.0 to approx. 0, weight percent F calculated on the weight of the finished catalyst.

It is generally preferred to carry out the gelation of the silicate component by the addition of carbon dioxide, but it should be noted that mineral acids such as sulfuric acid and hydrochloric acid may also be used to gel the alkali metal silicate if desired. When 7 U4873 CO 3.0. Preferably, the CO 2 released from the reaction mass is collected and reused in a subsequent gelling process.

Although it is generally preferred to add the clay soil and zeolite to the alkali metal silicate solution, however, the clay soil and any zeolite can also be added to the material together with the magnesium oxide component. As a rule, however, the most uniform dispersion of the clay soil in the catalyst will be obtained when the clay soil is added to the alkali metal silicate prior to its gelation.

In a typical embodiment of the process of the present invention, an aqueous slurry of clay soil is added to an aqueous sodium silicate solution and mixed thoroughly with it.

The clay soil / silicate slurry is then mixed with carbon dioxide which causes gelling of the silicate component. The gelled mixture is then preferably aged for a period of approx. 15 to approx. 120 minutes at a temperature of approx. 38 to approx. 49 ° C. After aging, the mixture is then acidified by the addition of sulfuric acid, during which stage the pH of the gel mixture is adjusted to approx. 3 to 4.

During the addition of sulfuric acid, carbon dioxide is released and preferably collected and recycled to the initial gelling step.

A magnesium oxide slurry comprising magnesium oxide dispersed in dilute mineral acid is then prepared. This magnesium oxide slurry comprises hydrated magnesium oxide and water and is then mixed with the gelled clay / silicate slurry. This joint mixture is then aged for a period of approx. 1 to approx. 3 hours at a temperature of approx. 52 ° C to approx. 74 ° C. At this point, if desired, the fluoride component is added in the form of hydrogen fluoride. After the addition of hydrogen fluoride (HF), the excess water filtration composition is filtered and then resuspended with water and spray dried. The spray-dried product, which will then exhibit a particle size of the order of 10 to 100 µ, is then collected, resuspended with water and aged from ca. 1 to approx. 4 hours at a temperature of approx. 63 to approx.

85 ° C. The aged, spray-dried catalyst is then resuspended in (NH 1 SO 2 solution) and washed and finally dried.

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It is shown in the Examples below that the catalyst prepared by the process of the invention has a high degree of hydrocrack cracking activity and additionally exhibits good thermostability and wear resistance when subjected to hydrocarbon cracking conditions.

Example 1

A silica / magnesium oxide / fluoride catalyst containing 30% by weight of clay soil is prepared by the following procedure.

7220 g of kaolin is added to 170 liters of sodium silicate solution containing 18.5 g of Na 2 liter and 6l, 2 g SiOg per liter. liter. The slurry is kept at a temperature of 52 ° C and pumped at a rate of 3.8 liters per minute. per minute through a reaction coil through which carbon dioxide is sent under pressure. The CO 2 stream is fed at such a rate that the stream leaving the reaction zone is gelled within 15 seconds at a reaction temperature of 52 ° C.

The resulting silica gel / clay slurry is then aged for approx. 1 hour at 52 ° C. Then, the slurry is combined with 4600 ml of 39 $ sulfuric acid, which lowers its pH to 3.0.

A slurry of dehydrated magnesium oxide is prepared by combining 2340 g of calcined MgO and 3 liters of water at 57 ° C. Then add another 4 liters of water along with 1350 ml of 39 $ sulfuric acid. This slurry is then combined with the above-mentioned silica gel slurry, whereupon the pH of the mixture is found to be 8.7 °.

1.5 hours at 71 ° C. This magnetic gel is then rapidly cooled to room temperature and 520 g of 48 $ hydrogen fluoride solution (HF) is added. At this point, the pH of the mixture is 7 * 8. The entire portion is then filtered and the filter cake resuspended with water, homogenized and spray-dried then dried. The screen size of the spray-spray-dried product is primarily in the range of 200 mesh (US sieve series). The spray-dried product is then washed with water, heated to 82 ° C for approx. 3 to approx. 4 hours and then washed 4 times with ammonium sulfate solution at a temperature of 43 ° C.

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The dried finished catalyst contains the following components: MgO = 19 * 65% by weight, Al2O2 = 15.10% by weight, SO2 = 0.10% by weight and F = 1.85% by weight, the remainder being SiO2 ·

Example 2 (Comparative Experiment)

For the preparation of a catalyst sample for comparison purposes, the procedure of Example 1 is repeated, however, the kaolin component is omitted. The analysis of the resulting catalyst is found to be as follows: MgO = 28.14 wt%, SO 2 = 0.11 wt%, F = 2.72 wt% and the residue SiO 2 ·

Example 5

The catalysts of Examples 1 and 2 are then subjected to a thermal treatment which involves heating at a pressure of 4.2 ato (corresponding to 5.2 ata) in water vapor at 538 ° C for 24 hours in a fluidized bed followed by heating to 84 ° C. C for 5 hours. The surface area and total pore volume of the products are determined after each individual thermal treatment. The results are given in the table below:

Table I

Catalyst_Example 1_Example 2 2 2

Initial surface area 442 m / g 665 m / g o p

Equilibrium surface area 256 no / g 296 m / g

Pore size 0.58 cm 2 / g 0.59 cirn / g 0.51 * 0.69 *

Davison wear index 26.8 l6.8 sH20 pore volume.

The above data indicates that the catalyst prepared according to the invention in Example 1 has lower surface area and pore volume than the control catalyst (prepared according to Example 2). It should also be noted that the thermostability of the product of the process of the invention and its abrasion resistance are acceptable sizes, although the product contains 30% by weight of kaolin. The percent reduction in surface area induced by the heat treatment is less for the catalyst composition prepared according to Example 1 than for the catalyst of Example 2.

Example 4 A) Hydrated calcined magnesium oxide (MgO) is prepared by combining 1670 g of MgO (4 # HgO) with 5025 ml of water of 66 ° C.

After 1.5 hours, 950 ml of 39% HgSO 4 solution is added.

B) A clay / silica gel slurry is prepared by combining 5060 g of kaolin (14.1 # H 2 O) with 170 liters of sodium ciliate solution containing 13.0 g of Na 2 O and. 43 g S liter. This slurry is pumped at a rate of 3.8 liters per minute. per minute through a heated reaction coil into which CO 2 gas is pumped at such a rate that the silicate is gelled at 52 ° C over 5 minutes. The gelled slurry is aged for 1 hour at 52 ° C. Next, 3305 ml of 39 $ HgSO 4 solution is added to give a clay soil / silica gel slurry * having a pH of 2.9.

C) The hydrated magnesium oxide slurry prepared under point A above is added to the clay soil / silica gel slurry from above point B. The temperature of the mixture is maintained at 66 ° C for approx. 2 hours. The pH of this mixture is 8.35.

D) The reaction mixture from above point G is stirred and 187 g of 48 # HF solution is added. 15 minutes after the addition of the HF solution is complete, 868 g of calcined zeolite exchange exchange rare earth is added to a slurry containing 33.5 µm solids. The resulting slurry is stirred for 1 hour and then filtered. A 42 kg filter cake is obtained which is suspended with water and spray dried. The spray-dried product is aged at 74 ° C for 1 hour. This product is then washed four times with dilute ammonium sulfate solution of 43 ° C.

The washed product is dried at 204 ° C. The final product analysis is as follows: u 144873 A1203 14.0¾¾

Na20 0.04 #

MgO 17.721 F 1.22%

Si02 balance

Surface area (after 3 b at 538 ° C). - 407 m 2 / g 2

Equilibrium surface area - 174 m / g

Pore volume - 0.58 cm 2 / g (HgO)

Davison's wear index 31.2.

Example 5

The properties of cracking catalyst in the compositions of Examples 1, 2, and 4 are determined by first subjecting them to an activation treatment of Example 3 and then subjecting the thus-produced catalysts to cracking conditions using a heavy gas oil from West Texas at a temperature of 483 ° C. . The test results thus obtained are shown in the table below, which illustrates the cracking properties of all the catalyst compositions.

Table II

Catalyst_Example 1 Example 2 Example 4

Conversion at a room rate of 10 weight units per hour 61.5 vol. # 60.0 vol. # 71.0 vol. # H2 0.051 weight # 0.047 weight # 0.033 weight # 0χ and C2 1.8 weight # 1.7 weight # 1.7 weight # 6.8 weight # 5.9 weight # 8.6 weight #

CJJ. 8.1 weight # 7.1 weight # 8.5 weight #

CPU and petrol 55.0 weight # 54.5 weight # 63.5 weight #

Light circulating oil 16.5 weight # 16.7 weight # 13.5 weight #

Coke 3.8 weight # 3.6 weight # 3.4 weight #

The data given above clearly shows that the catalyst prepared according to the invention in Examples 1 and 4 has excellent activity, although significant amounts of clay soil are present.

In addition, in both cases the catalyst exhibits excellent selectivity in light circulating oil.