DE1110351B - Process for the production of a microspheroidal silica-alumina fluidized bed cracking catalyst - Google Patents

Description

Process for the preparation of a microspheroidal "silica-alumina fluidized bed cracking catalyst This invention relates to a method of making a high level microspheroidal silica-alumina fluidized bed cracking catalyst.

Earlier attempts were made to get dry substances into the cracking catalysts to introduce, with the emphasis on lowering manufacturing costs and Avoidance of overheating during regeneration was put without losing any essential To seriously impair properties of the cracking catalyst.

The use of kaolin as a substitute for an alumina catalyst was already known. But it was only known that kaolin was a silicon dioxide gel and not to add to an alumina-silica gel.

There was also a method of making a similar silica-alumina catalyst by independently manufacturing a silica hydrogel and an alumina hydrosol and mixing the two ingredients and subsequent drying at about 120 ° C known, but without the addition of kaolin having played a role.

The addition of kaolin to a silicon dioxide-magnesium oxide hydrogel was also done or a silica-magnesia-aluminum hydrogel.

However, simply mixing dry substances with hydrogels results before drying to a product with an excessive amount of fines and poor frictional properties, indicating uneven shrinkage during drying is due.

It is an object of the present invention to provide a commercially useful one to produce mierospheroid flowing silica-aluminum cracking catalyst, contains substantial amounts of a cheap additive and has a good particle size distribution, in particular has the same particle shape, the additive in intimate connection with the catalytic material, thereby reducing the heat distribution during the carbon burn off is improved, which has the effect of extending the life of the catalyst.

The invention also relates to such a silica-alumina cracking catalyst manufacture in which the catalyst and the additional components do not tend to be classified as having significantly lower manufacturing costs than before and which allows more catalyst to be used, eliminating metal contamination and so the separation is improved.

The invention consists in that an inorganic additive in a proportion between 10 and 701/0, based on the total calcined solids of the final catalyst product, with an alumina-rich silica-alumina hydrogel intimately mixed and the silicon dioxide-aluminum oxide hydrogel and the finely divided one Additive can be connected to a degree equivalent to that by homogenization in a homogenization valve at a pressure between 21 and 210 atm, and that after that the Mixture of the silicon dioxide-aluminum oxide hydrogel and the additive, spray-dried is, the additional component not more than 20.1 / o before spray drying Contains particles coarser than 0.044. mm and the hydrogel component- before spray drying Contains no more than 40% of particles that are coarser are than 0.044mm.

The mixture should be carried out in such a way that the additional particles in the end product in direct contact with and enclosed by the silica-alumina gel are what can be detected microscopically. The mixture can be through several suitable means, such as B. rolling, grinding z. B. with a Fitzmühle, homogenize or a combination of these means.

Under an alumina-rich silica-alumina hydrogel, as the term is used here, one understands silica-alumina hydrogels, which is between 20 and 30% aluminum oxide, based on the dry weight of the hydrogel, contain.

"Annealed solids" is understood to mean the solids content after annealing at 1000 ° C.

These alumina-rich silica-alumina hydrogels can be prepared by several suitable methods. According to one method can hydrated silicon dioxide from a dilute solution of an alkali silicate, like the commercially available water glass, by acidification with a mineral acid, e.g. B. Sulfuric acid, to be precipitated. The precipitated, hydrated silica can then in an aqueous solution containing -an aluminum salt such as aluminum sulfate or Contains aluminum nitrate, can be suspended, and hydrated aluminum oxide can then by adding a basic compound such as ammonia to the hydrated one Silica is precipitated, creating a silica-alumina slurry forms. Details of this general procedure are in U.S. Patent 2 701793.

Another suitable method for making a silica-alumina hydrogel high alumina relies on precise control of the chemical Reaction between an alkali aluminate and alum in an aqueous suspension of a pre-precipitated hydrated silica; through such precise control hydrated aluminum oxide can be precipitated and the suspended silicon dioxide coat and thus form a composite gelatinous material from the undesirable Alkali metals and other water soluble salts easily by washing and filtering can be removed without major complications.

No matter what method of making the alumina-rich Silica-alumina material is used, the essential point is that a nearly fully hydrated gel or hydrogel instead of a xerogel or dried gels is used.

The inorganic dry additive added to the hydrogel can either be in terms of catalytic activity compared to the silica-alumina fraction of the final catalyst product, or a relatively inert material with respect to this Activity completely inert substance. Finely divided inorganic substances can be used as additives silica-based, such as silica flour, various clays, such as natural or uncalcined kaolin clay, Fuller's earth or the like, can be used. Preferably these additives are alali-free. With regard to these additives, it should be noted that silica flour is an essentially inert additive, while kaolin and Fuller's earth, catalytically speaking, have some activity.

These substances should have an average particle size of no more than 20, preferably no more than 8 microns. Usually they are commercial additives before they are intimately combined with the hydrogel, so characterized. Unless. can by homogenization or other suitable Medium such particle sizes can be obtained.

The addition is the alumina-rich silica-alumina hydrogel in quantities. between 10 and 70, preferably between 40 and 60 percent by weight of the end product of the catalyst are added in order to achieve an optimal effect.

The additive can be filtered, washed and slurried Silica-alumina hydrogel can be added. He can also be a homogenized Hydrogel can be added if the mixture is intimately connected afterwards. So can generally the addition of the additive to the hydrogel at some point in the process take place as long as the additive and the hydrogel are intimately connected during spray drying are.

It is an essential part of this invention that the additive and the silica-alumina hydrogel to provide a suitable catalyst product must be in close contact with each other.

It has been found that there is a corresponding intimate connection can be achieved by crushing the mixture of additive and hydrogel during passing through a homogenizer, such as. B. an ordinary spring-operated Homogenization valve, or by homogenizing the hydrogel and then intimate connection with the addition. In this context, it has been established that the degree of association necessary for the invention is to be defined as the amount that by homogenizing the hydrated silica-alumina and of the additive in a spring-operated homogenizing valve at a pressure between 21 and about 210 at and preferably a value between about 70 and 140 at will. It should be mentioned that homogenization as a means of achieving the desired intimate degree of association is mentioned purely by way of example and every means of achieving it of the desired intimate degree of association as completely consistent with this Invention is to be considered.

The degree of homogenization within the pressure limits defined above or similar means for attaining the required intimate association may be through wet sieving of the hydrogel component can be determined and every homogenization or a comminution method that provides a Hodrogel that is no more than 40%, preferably does not appear to contain more than 30% of particles larger than 0.044 mm in size to be suitable.

Besides using a homogenizer, homogenization can also be done can be achieved by applying a strong nozzle pressure during spray drying. If, after using the conventional homogenizer, nozzle pressures during spray drying are used, the pressure above a valve in at and the nozzle pressure in at additive, and the sum is called the degree of homogenization consider, either when using the homogenization valve or the nozzle pressure alone would be achieved.

After the additive and the silica-alumina hydrogel are intimately mixed, they are by spraying the mixture through a nozzle or a spray wheel dried in contact with hot gases. Such drying can be done with anyone suitable spray dryer such as that described in U.S. Patent 2,644,516; are executed. Although gas inlet temperatures up to 700 ° C are used are the temperatures of the drying gas going into the spray drying chamber occurs, preferably to keep within a range of 205 to 540 ° C, so that the silica-alumina hydrogel is in intimate association with the surrounding area Material converted into solid, partially dehydrated, microspheroidal gel particles will. Spray drying usually results in a moisture content that is between 7 and 1.5 "/ o of the spray-dried product lies.

The catalyst of the present invention works like other commercially available silica-alumina cracking catalysts used in fluidized bed conversion processes in which a high boiling petroleum hydrocarbon is catalytically cracked to produce high octane gasoline. In such Processes, as known to anyone skilled in the art, are located in the catalyst particles suspended in a gaseous stream of hydrocarbon and cracking is at a temperature between 370 and 590 ° C, preferably between 480 and 540 ° C.

The following examples are intended to illustrate the invention in greater detail to serve. All parts and percentages given here relate to the weight, unless otherwise noted. Example 1 An alumina-rich silica-alumina hydrogel filter cake (25 "/ o alumina on a dry weight basis) made in accordance with U.S. Patent No. 2,701,793, which contains 10% solids, was used for preparation a slurry with 7.51 / o solids content diluted with water.

Slowly became a silica-alumina flour, which is an average Has particle size less than 20 microns and by no more than 10% particles, coarser than 0.044 mm, into one of those in the slurry given solids equivalent amount. Stirring was carried out during the addition. Sufficient water was then added so that all of the solids, i.e. H. in silica-alumina hydrogel and silica flour, equaled 12.5%.

This slurry continued for an additional 15 minutes mixed and driven through a homogenization valve at a pressure of 70 at and at an inlet temperature of 345 ° C and a nozzle pressure of 49 to 70 at spray dried. This degree of homogenization is sufficient to achieve that not greater than 40% of the hydrogel particles are larger than 0.044 mm.

The end product was a microspheroidal catalyst material that 50% silicon dioxide flour and 50% silicon dioxide-aluminum oxide catalyst in intimate Containing mixing.

Example 2 An alumina-rich silica-alumina filter cup (25! 1 / o aluminum oxide, based on the dry weight) made in accordance with according to U.S. Patent 2,701,793, which contains 109% solids, was used for manufacture a 7.5% solids slurry diluted with water.

A quantity of finely divided kaolin clay suitable for papermaking, characterized by a particle size distribution in which less than 10% of the Particles coarser than 0.044 mm and an average particle size of less than 20 microns, slowly became a slurry with vigorous agitation given. Then the silica-alumina-kaolin slurry became sufficient Added water to achieve a solids content of 12.51 / o. For another 15 Minutes was continuously mixed. The slurry became thin with one pressure of 70 at and using an inlet temperature of 345'C through a homogenization valve driven and spray-dried at a nozzle pressure of 70 at. This degree of homogenization is sufficient to demonstrate that not more than 40% of the hydrogel particles are coarser than 0.044 mm are.

The end product was a microspheroidal catalyst material which contained 50 019 kaolin and 501 / o silicon dioxide-aluminum oxide catalyst intimately mixed.

Example 3 The procedure used in Example 1 was followed with the exception that the amount of silica flour added was so great that that the final catalyst is 30% silica flour and 70% silica-alumina catalyst contained in intimate mixing.

Example 4 The same procedure as in Example 1 was carried out with the exception that the amount of silica flour added was so great that the final catalyst 7011 / o silicon dioxide flour and 30 0 / o silicon dioxide-aluminum oxide catalyst contained in intimate mixing.

Although a higher spray drying temperature to achieve a shortened Production time can be used is in accordance with this invention spray drying of the intimately mixed additive and the silicon dioxide-aluminum oxide catalyst material preferable at an inlet temperature between 260 and 425 ° C; it should be noted that higher inlet temperatures, e.g. B. 650 ° C, to a breakage of the individual particles and therefore leads to an undesirable attainment of fines.

The table is provided to compare the improved catalyst of this invention with commercially available silica-alumina cracking catalysts. Example Example Example Example Catalyst Catalyst 1 2 3 4th A. B * activity F ......................... 67 73 74 45 110 120 S ...................... ... 17 20 21 13 22 29 C ......................... 50 - - - - 73 Gas factor F ......................... 1.2 1.2 1.2 1.2 1.1 1.2 S ......................... 1.2 1.3 1.1 1.2 1.1 1.2 C ......................... 1.6 - - - - 1.8 carbon F ......................... 1.4 1.4 1.5 1.7 1.2 1.4 S ........: ................ 1.4 1.4 1.3 1.2 1.2 1.4 C -......................... 2.4 - - 2.6 Carbon on fresh catalyst, 0/0 8 10 9 6 14 18 Apparent bulk density, g / ccm F ......................... 0.52 46 0.44 0.51 0.47 0.47 S ......................... 57 52 0.50 0.60 0.57 0.59 Pore volume, ecm! G. . . ... . . . . . . 0.46 0.58 0.34 0.72 0.70 0.70 Surface, m- / g ................ 260 344 350 160 570. 496 The same hydrogel as for Examples 1 to 4. »American Cyanamid Manual of Test Me- thods for Synthetic Fluid Cracking Catalog F = freshly calcined for 1 hour at 590 ° C. lysts ", 1957. S = 17 hours under steam at 750 ° C. C = After contamination with 0.10! O Ni. Catalyst A = 13% aluminum oxide, silicon dioxide-aluminum Accelerated test to determine stability. Values of the minium oxide catalyst. registered under "S" are measured after 1 hour catalyst B - 25% aluminum oxide, silicon dioxide-aluminum Operation in a cracking unit, corresponding to the miniumoxide catalyst. Gas factors, carbon factors, apparent bulk density, pore volume and surface area were determined in accordance with the aforementioned cyanamide publication.

The table above illustrates that those treated with steam Catalysts according to the present invention, which contain 50% additive, the Activity of the steam-treated, commercially used 13% aluminum oxide Silica-alumina catalysts.

In detail, the table also shows that according to the present invention produced catalysts have significantly lower proportions of carbon in the fresh Contains catalysts. The occurrence of relatively high levels of carbon in the So far produced aluminum oxide catalysts, which are in their rapid deactivation express (less constant activity), relies on stronger burnout and greater Total heat development during regeneration. In this context it should be mentioned that rapid deactivation caused by regeneration in the instantaneous commercial catalysts, in de: Mainly from the inability that produced Distributing heat stems from. In the catalyst of this invention, there is this disadvantage at least partially overcome by the fact that the additive component, either is inactive or relatively inactive, absorbs significant amounts of heat and therefore the active component is not deactivated as quickly.

Another surprising result that the table above shows., is that even when the catalysts described in Examples 1 and 2 50% additive, the activity at the beginning and after steam treatment, especially with the addition of kaolin with over 501 / o more than that of the aluminum oxide-rich silicon dioxide-aluminum oxide catalyst material amounts to.

Another unexpected aspect of this invention is that Nickel contaminated and poisoned catalysts of this invention are carbon and carbon Have gas factors that are significantly lower than the standard 251/9 Alumina-containing silica-alumina cracking catalysts. With Considering the fact that the catalyst of the present invention is on a weight basis related, only half the number of active sites of the catalyst with 25% Contains aluminum oxide, one would expect the carbon factor to be twice as great like that of an alumina-rich catalyst.

Another embodiment of the present. Procedure consists in either the commercially available silica-alumina catalyst with low Alumina content, e.g. B. with 13% aluminum oxide, to modify or simply such catalysts in place of the modified catalysts previously indicated to use. As for the first procedure, it is clear that such a change of the low alumina catalyst by a substantial degree would lead to a relatively low activity of such a catalyst, since the proportion of aluminum oxide and thus the catalytic sites it contains are slightly under can decrease a permissible value. Furthermore, a special and important one would be Benefit of this invention will be lost. This advantage is that in the Modification of an alumina-rich silica-alumina flow cracking catalyst material a final catalyst product is easily and inexpensively formed, the one Has an acceptable number of catalytically active sites.

As has been emphasized, the catalyst according to the invention has lower values Manufacturing costs than comparable silica-alumina catalysts for numerous obvious reasons. So it is for making a silica-alumina hydrogel With a high aluminum oxide content not necessary, the hydrogel to achieve a desired Alkali metal and sulfate content based on the final catalyst product, strong to wash.

While the present invention is primarily used in conjunction with silica-alumina catalysts of the high alumina type, d. H. with a content of 25 percent by weight aluminum oxide, has been described, small proportions of other catalytically active substances, such as B. titanium dioxide, magnesium oxide, boron oxide, in the catalyst composition according to the invention be present for special purposes.

Claims (5)

PATENT CLAIMS: 1. Process for the production of a microspheriodal silicon dioxide-aluminum oxide fluidized-bed cracking catalyst, characterized in that an inorganic additive in a proportion between 10 and 7004, based on the total calcined solids of the end catalyst product, with an aluminum oxide-rich silicon dioxide-aluminum Hydrogel intimately mixed and the silicon dioxide-aluminum oxide hydrogel and the finely divided additive are combined to a degree that corresponds to that obtained by homogenization in a homogenization valve at a pressure between 21 and 210 at, and that then the mixture of the silicon dioxide-aluminum oxide Hydrogel and the additive is spray-dried, the additional component prior to spray drying not containing more than 20% of particles which are coarser than 0.044 mm and the hydrogel component prior to spray drying not containing more than 401% of particles which are coarser than 0.044 mm . 2. The method according to claim 1, characterized in that the silicon dioxide-aluminum oxide hydrogel homogenized in a homogenization valve at a pressure between 21 and 210 atm before it is intimately mixed with the additive. 3. The method according to the claims 1 and 2, characterized in that as an additive silicon dioxide flour, kaolin or Fuller's earth can be used. 4. Method according to any of the foregoing Claims, characterized in that 40 to 6019 / o of the additive, based on the Total amount of calcined solids of the final catalyst product, with the silica-alumina hydrogel be mixed. 5. The method according to any one of the preceding claims, characterized in that the homogenized material is at an inlet temperature spray-dried between 260 and 425 ° C. Considered publications: French Patent No. 1041042; British Patent No. 724 567; UNITED STATES.- Patent Nos. 2,763,622, 2,768,145.