WO1997012011A1

WO1997012011A1 - Bottoms cracking catalysts

Info

Publication number: WO1997012011A1
Application number: PCT/US1996/014973
Authority: WO
Inventors: Edward J. Demmel
Original assignee: Intercat, Inc.
Priority date: 1995-09-25
Filing date: 1996-09-18
Publication date: 1997-04-03
Also published as: AU7363596A

Abstract

This invention relates to processes for making and using bottoms cracking catalysts that are particularly characterized by the fact that they contain an aluminosilicate compound wherein a SiO2 component is chemically reacted with an alumina component before the resulting aluminosilicate compound is mixed with the other ingredients employed in a slurry formulation used to make the BCA.

Description

BOTTOMS CRACKING CATALYSTS

BACKGROUND OF THE INVENTION

1. Field of the Invention. This invention generally relates to so-called "bottoms cracking catalysts." Such catalysts are used to crack heavier fractions of petroleum (e.g., those boiling above about 800°F) . More particularly, the present invention relates to bottoms cracking catalysts employed as "additives" to those bulk catalysts (e.g., zeolite-containing catalysts) used to crack petroleum in fluid catalytic cracking ("FCC") units. Such additives are often referred to as bottoms cracking additives ("BCAs") .

2. Description of Related Art. Since the 1960's, a wide variety of petroleum cracking reactions have been carried out in FCC units using that class of small crystalline aluminosilicates known as zeolites. For example, U.S. Patent No. 3,703,886 discloses a variety of zeolites having especially high petroleum cracking activities. Zeolites of the Y-faujasite type are especially active in those catalysst used to crack bulk petroleum. Other types of zeolites have been used in various catalyst "additives" (relatively small proportions of additives are usually employed in conjunction with much larger proportions of so-called "bulk catalyst") to crack certain specific petroleum components such as paraffins and olefins in the gasoline boiling range. A well known example of this type of zeolite would be ZSM-5 catalysts.

Crystalline zeolites such as y-faujasite and ZSM-5 are, however, too catalytically active and too small in size to be used in their own right in FCC processes. Consequently, zeolites are formulated into larger particles wherein the zeolite is both diluted and aggregated by use of a matrix material that is usually comprised of a clay component and a binder component. A wide variety of metal oxides have been used as such binder components. For example, it has been common practice to employ alumina and/or silica binders to produce zeolite- containing bulk catalyst particles having desirable catalytic activity, particle size, density and hardness attributes. When used for these purposes, such clay, alumina, silica, etc. are frequently referred to as the "matrix" of the resulting zeolite catalyst/binder material. The resulting composite material is often referred to as "the catalyst" even through the zeolite component provides most of its catalytic cracking capability. Matrices comprised of clay and metal oxide binders also have been employed in the more specialized "additive" particles to which this patent disclosure relates.

Next, it should be noted that in many zeolite- containing, bulk FCC catalysts, the matrix material is catalytically inert, i.e., it does not participate in any hydrocarbon cracking reaction. These inert matrices are often achieved through use of relatively high concentrations of inert silica. Other matrices are, however, purposely made catalytically active with respect to various components of a given hydrocarbon feedstock. This catalytic activity is often achieved through use of relatively high concentrations of alumina in the matrix component of such zeolite/matrix composite particles. This alumina may be either crystalline or amorphous in character. And, as might be expected, a wide variety of matrix materials having catalytic activities between these extremes have been designed for a host of specific catalytic cracking duties. In most cases however, catalytically active matrices have far less catalytic activity relative to that of any zeolite components present in a FCC catalyst inventory. Those skilled in this art also will appreciate that all zeolites have one property in common - they have a "port opening" leading into their interior surfaces where their catalytic functions are actually carried out. This port opening is generally about 7.4 Angstroms in diameter - and this dimension usually remains more or less fixed regardless of the zeolite's chemical composition, or how it was originally made. This port opening size limitation implies that both the reactants and the products of any chemical reaction that occurs on a zeolite's interior surface must be small enough to readily pass through the zeolite's port opening. Those skilled in this art also will appreciate that the high molecular weight components of crude petroleum (i.e., those components boiling above about 800°F) are much too large to pass through a 7.4 Angstrom opening.

One fairly straightforward solution to this limitation was simply to pre-crack those "oversized" molecules that make up the higher boiling components of petroleum so that the fragments resulting from such a pre-cracking step can be further cracked by a zeolite component contained in the FCC unit's overall catalyst inventory. This pre-cracking step is often accomplished through use of a separate and distinct class of particles known as bottoms cracking catalyst ("BCAs") , or through use of zeolite-containing, bulk catalyst particles that also have matrix components that are catalytically active with respect to those large petroleum molecules found in bottoms fractions. Both forms of bottoms cracking catalyst usually employ catalytically active metal oxide materials such as alumina as the large molecule breaking catalyst. The relative success of these two technologies generally follows from the fact that, unlike zeolites, metal oxides such as alumina have no restrictions on the size of the molecules they can crack because their catalytically active sites are on their outer surfaces - regardless of whether they are used as separate particles or as matrix materials for zeolite particles.

In the case of using separate and distinct BCAs, the BCA particles are simply periodically mixed into a bulk catalyst particle stream as it circulates through the FCC unit. Very often, the point of entry is the FCC unit's catalyst regenerator. In any case, these separate and distinct BCA particles serve to crack petroleum's larger molecules into fragments that are small enough to pass through the port opening of a zeolite component of a bulk catalyst circulating in admixture with the BCA particles. Thus, for this catalytic action to take place, the relatively smaller petroleum molecules created by the BCA component of the catalyst inventory must "transfer" to the bulk catalyst particles for "final" cracking to the most desirable molecular sizes (e.g., those of gasoline) .

Conversely, no such inter-particle transfer is necessary when a zeolite-containing bulk catalyst particle is provided with its own bottoms cracking component as a part of its matrix. For example, amorphous alumina has been widely used as a matrix ingredient in order to form a composite catalyst particle that is capable of cracking both larger petroleum molecules requiring "pre-cracking" as well as those smaller molecules that are capable of entering the port opening of the zeolite component of such composite particles.

Such composite catalysts do however suffer from one very serious drawback. This revolves around the fact that crude petroleum contains trace amounts of various metals - especially nickel and vanadium. These metals are contained in large complex molecular structures that are soluble in crude petroleum. When these large, complex, molecules are subjected to petroleum cracking e.g., on alumina's outer surfaces, they tend to deposit their metallic components on the active sites of the matrix of such catalysts. Metal depositions of this kind quickly destroys the pre-cracking capability of the material. Worse yet, nickel deposition on the active sites of the matrix serves to transform them into hydrocarbon dehydrogenation sites. This constitutes a major problem because if relatively large petroleum molecules encounter a dehydrogenation site, and thereby lose hydrogen atoms, they tend to form a class of materials known as polynuclear aromatics. Polynuclear aromatics are precursors to the formation of coke - anathema to the hydrocarbon cracking activity of all FCC catalysts. Indeed, not only does such coke formation slow down the rate of cracking reactions, it too tends to alter the overall petroleum product distribution toward less desirable products (e.g., toward heavy fuel oil production - and away from gasoline production) . The chemical mechanism by which such dehydrogenation occurs is fairly well understood. When a FCC atmosphere is strongly oxidizing, metallic nickel reacts to form nickel oxide. In its oxide form, nickel is a very poor dehydrogenation catalyst. When, however, a nickel-containing catalyst flows from a FCC unit•s regenerator back to its hydrocarbon cracking reactor, where the atmosphere is strongly reducing, the nickel oxide is reduced back to metallic nickel - a very good dehydrogenation catalyst - that quickly "poisons" a BCA's ability to act as a hydrocarbon cracking catalyst. This metal poisoning problem also is aggravated by the fact that metals such as nickel are associated with the heaviest fractions in crude petroleum. Thus, the greater the need for a pre- cracking component, the higher the amount of nickel that tends to be deposited on the catalyst's active sites. Yet another problem in this set of circumstances follows from the fact that the very components of the catalyst matrix that are highly desirable to pre-crack high molecular petroleum fractions (e.g., alumina) also tend to stabilize nickel. Consequently, the dehydrogenation activity of nickel is tenacious. Conversely, certain other matrix components such as silica, that are not active pre-cracking catalysts, tend to deactivate nickel.

As previously noted, one solution to the array of problems noted above was to use an "additive approach" (as compared to a composite particle approach) wherein additive particles with active matrix components were physically mixed with a bulk cracking catalyst in order to perform the pre- cracking function. This approach was not initially well received by the petroleum industry since it was then widely believed that if the high molecular weight compounds did crack on such additive particles, the reaction would - undesirably proceed still further to form unwanted gas and coke products. Eventually, some workers, (most notably, M. M. Mitchell Jr. and H. F. Moore of Ashland Petroleum Company) successfully challenged the view that a separate catalyst particle with a highly active matrix would invariably result in high yields of coke and gas. They carried out an extensive experimental program that utilized an "additive approach" to cracking the heavier molecular components of petroleum. The results of their work came somewhat as a surprise to the petroleum refining industry. Mitchell and Moore demonstrated that a BCA containing a zeolite component, as well as an amorphous metal oxide, and used in the form of separate and distinct additive particles (rather than as a BCA component part of a bulk hydrocarbon cracking catalyst particle), would crack petroleum's heavy components into lighter molecules without unacceptable rates of coke formation. They also demonstrated that the lighter molecules resulting from such cracking, in large proportions, would, successfully transfer to separate and distinct zeolite-containing bulk catalyst particles where they were in fact further cracked into more desirable products. Mitchell and Moore reported that in order for their amorphous alumina, BCA particles to be most effective, a small, but very significant, amount of zeolite was needed. Their best results were obtained with BCAs having a 2% zeolite component. Even more surprising to the industry was their finding that this additive approach actually reduced the relative amount of coke that was formed on the surface of their zeolite-containing BCA particles. The results of their work were published in a paper presented to the American Institute of Chemical Engineers in 1990 under the title: "Improvement of FCC Performance with Bottoms Cracking Additives". This paper is very relevant to the teachings of this patent disclosure and is therefore incorporated by reference herein.

Thus, summing up the state of this art prior to the invention of the hereindescribed BCAs, it was well known that high molecular weight petroleum components are much too large to enter the port openings of crystalline zeolites. Hence, these large molecules were pre-cracked on the acid sites found on the surfaces of various amorphous, catalytically active, materials such as alumina. These materials were used in the form of separate and distinct BCA particles, or they formed a part of the matrix of various zeolite-containing, bulk hydrocarbon cracking catalysts. When, however, metals, (particularly nickel) , are deposited on the active sites of such materials, high molecular weight petroleum components coming into contact with such sites are dehydrogenated rather than cracked. Such dehydrogenation reactions lead to formation of undesired polynuclear aromatic and/or coke materials as well as to high yields of less desirable products.

In response to the problems existing in the above set of circumstances, applicant has found a way to crack high molecular weight compounds before they are dehydrogenated by catalyst sites that fall prey to nickel poisoning. Use of the hereindescribed compounds also produces high yields of gasoline and, hence, low yields of heavy fuel oils and/or coke. These desirable results are achieved through use of certain hereinafter described aluminosilicate-containing BCA compositions. SϋMMARY OF THE INVENTION

BCA Compositions

Applicant has found that greatly improved BCA functions can be accomplished through use of BCAs having an aluminosilicate compound wherein a silicon dioxide component is placed in an alumina molecular structure in order to create an alumina/silicon dioxide compound that exists in a chemically compounded aluminosilicate form in the final product - as opposed to being incorporated in an otherwise comparable BCA particle in the form of a separate silicon dioxide phase that is merely physically mixed with a separate alumina phase. The improved BCA functions resulting from use of such alumnosilicates are many and varied. For example, applicant has found that, when the compounds resulting from the chemical reaction of silicon dioxide and alumina compounds are employed in the hereindescribed BCAs, the yield of coke as well as the yield of less undesired products (e.g. heavy fuel oils) is greatly reduced compared to the results obtained from otherwise comparable BCAs wherein alumina and silicon dioxide ingredients are merely mixed with each other in a preparative slurry rather than being chemically reacted before they are placed in such a preparative slurry.

The bottoms cracking additives of this patent disclosure may have either of two general formulations. In the first formulation, the end product BCA will be comprised of an aluminosilicate compound wherein a Siθ2 component is a chemically compounded part of an aluminosilicate and wherein the other components of the BCA are an acid- dispersible alumina, a clay and a non-dispersible alumina. In applicant's second formulation, a phosphate compound (such as an ammonium phosphate compound) will, in whole or in part, replace the non-dispersible alumina component employed in the first formulation. Thus, the two aluminosilicate compound-containing end product BCAs of this patent disclosure will be comprised of either: (1) an aluminosilicate compound wherein a Siθ₂ component is chemically compounded with an alumina component, an acid-dispersible alumina, a clay and a non- dispersible alumina or (2) an aluminosilicate compound wherein a Si0₂ component is chemically compounded with an alumina component, an acid- dispersible alumina, a clay and a phosphate- containing compound. Optionally, either of these BCA formulations may have a relatively small silica component (e.g., less than about 5% by weight) that is not reacted with an alumina component. Where necessary, this silica component will be referred to as "unreacted silica" in order to differentiate it from the silica that is compounded with alumina to produce applicant's aluminosilicate ingredient.

Two slightly different production procedures can be used to make applicant's respective bottoms cracking additives. More detailed descriptions of each of these production procedures will be given in ensuing portions of this patent disclosure. But, before going on to the details of such procedures, it should be specifically noted that, when the aluminosilicate compounds of this patent disclosure (i.e., those wherein Siθ₂ is in an aluminosilicate crystalline structure) are employed in place of otherwise identical ingredients (i.e., compositions having the same ingredients, but wherein the alumina and the silica exist as separate phases rather than as a chemical compound) , the resulting BCAs are very significantly different in their physical attributes and, more important, in their ability to perform as BCAs.

For example, the hereindescribed BCAs can be physically distinguished from prior art silica phase/alumina phase solid solution BCAs by the fact that applicant's BCAs have surface areas of from about 150 to about 175 m²/g. By way of comparison, when otherwise comparable silica and alumina ingredients are not placed in an aluminosilicate crystalline structure before said alumina and silica ingredients are mixed with an acid-dispersible alumina ingredient - a la the teachings of this patent disclosure - any BCAs produced from otherwise identical ingredients (and otherwise identical preparation steps) will have surface areas of only about 100 to about 125 m²/g. While not wishing to be bound to any particular theory, applicant believes that this difference in surface area fully explains, or at least very significantly contributes to, the fact that BCA's made from non-compounded alumina and silica components have very decidedly inferior bottoms cracking capabilities. In addition, those BCA's made using applicant's aluminosilicate ingredients have relatively better thermal stability. They also are better able to retain their surface areas upon repeated exposure to those high temperatures existing in a FCC unit.

In discussing these relative catalytic capabilities, it also should be noted that measurement of the comparative acidity of a matrix material used in the presence of a y-faujusite zeolite is extremely difficult from an experimental point of view. This follows from the fact that the Y-zeolite component is so strongly acidic. There are however techniques available for making such measurements. Perhaps the most widely accepted ethod is that described by Saeed Alerasool et al; I&EC RESEARCH, 1995, 34. Dr. Alerasool and his co- workers showed that the lowest acidity matrices in the catalyst materials that were studied had acidities of 5 μmole/gram while the highest had about 175 μmole/gram. By way of contrast applicant's BCAs have acid activities of from about 20 to about 350 μmole/gram. In any case, applicant regards the Alerasool*s methods as being particularly well suited for making such comparisons between applicant's BCAs and other catalytically active materials.

Applicant has, however, found that there is a "downside" to putting "too much" aluminosilicate and, hence, "too many" acid sites in the BCAs described herein. Applicant also has found that it is important that the hereindescribed BCAs pre- crack, as much as possible, only the higher molecular weight hydrocarbon components of a petroleum feedstock and that the fragments from such pre-cracking reactions be further cracked on zeolite-containing bulk catalyst particles that will be circulating in admixture with the hereindescribed BCAs. This requirement generally implies that the rate of bottoms cracking by applicant's BCAs should be designed to be less than the rate at which hydrocarbon fragments resulting from such cracking can diffuse from the circulating BCA particles to co-circulating zeolite-containing bulk catalysts. In other words, applicant believes that BCAs having

"too many" acid sites tend to crack various high boiling petroleum components too severely and this, in turn, leads to production of unacceptably large amounts of undesirable gas and/or coke products. Applicant has found that such a suitable a "balance" can be struck by variation of the relative proportion of the hereindescribed aluminosilicates in applicant's BCA end products.

Applicant has found that in order for production of undesirable gas and/or coke by applicant's BCAs to be held to acceptable levels, the silica component of the aluminosilicate compound of the hereindescribed BCAs preferably should be between about 0.5 weight percent and about 50.0 weight percent of the aluminosilicate ingredient. Applicant also has found that such a aluminosilicate ingredient should be used in proportions in the preparative slurry such that the BCA end products ultimately resulting from use of the hereindescribed ingredients and processes steps will have from about 0.25 to about 30 weight percent of the aluminosilicate ingredient. Even more preferably, the aluminosilicate component should constitute from about 2.5 percent to about 25 percent by weight of the BCA end product. Suitable, aluminosilicate compounds, wherein a

Siθ₂ component is a part of an aluminosilicate molecular structure, and certain preferred methods for their production, are described in U.S. Patent 5,045,519 ("the '519 patent) and its teachings are incorporated herein by reference. Generally speaking, the '519 patent teaches processes for preparing high-purity, thermally stable, catalyst carriers by use of such aluminosilicate compounds. They can be obtained by mixing certain aluminum compounds with a silicic acid compound in an aqueous medium, and subsequently drying or calcining the resulting product. The aluminum ingredient used in the production process of the '519 patent is preferably a C₂ to C2o~^al^um-^Lnum alkoxide that is hydrolyzed with water and purified by ion exchange procedures. They are usually obtained as byproducts of processes wherein aluminum is used to catalyze reactions employed to produce various alcohol products.

Those aluminosilicate compounds obtained from such processes are often referred to as "gel type" aluminas. They are characterized by the fact that they have surface characteristics that cause them to be "acid-dispersible". Indeed, they also are often referred to as "acid-dispersible aluminas" as well as "gel type aluminas". It also should be noted that the aluminas with which the silica is compounded, is itself, most preferably, an acid- dispersible type alumina. Aluminas from other sources (e.g., minerals, synthetically produced aluminas, not having the appropriate surface characteristics) are not similarly "acid dispersible" - and, hence, this "non-dispersibility" distinction will be made during the course of the teachings of this patent disclosure where differentiation between the different kinds of alumina used in the hereindescribed BCAs is appropriate.

Applicant also has found that when relatively large proportions of silica are used in the hereindescribed aluminosilicate compounds (such that the end product BCA has a silica component greater than about 10 weight percent of the BCA) , the resulting material may no longer be hard enough (i.e., attrition-resistant) to serve as a BCA. Under such circumstances, increased amounts of an auxiliary binder material, such as a clay, an unreacted silica, or a phosphate, may be used in order to make these high silica content materials sufficiently attrition-resistant. The importance of the fact that the chemically reacted silica component of applicant's BCA products is made a part of the molecular lattice structure of the aluminosilicate component of the hereindescribed BCAs also can be inferred from the fact that there are numerous silica-alumina BCA catalysts presently being used in the petroleum refining industry having decidedly less bottoms cracking capabilities relative to those forming the subject matter of this patent disclosure. Most of these prior art silica- alumina compositions are produced by mixing sodium silicate (water glass) with acid alum (aluminum sulphate) to produce a gel that is thereafter used as a matrix-forming material for many hydrocarbon cracking catalysts, but especially those bulk catalysts that contain zeolite particles. Matrices made from such silica phase/alumina phase materials are predominately comprised of silica (e.g. they often contain about 90% silica and 10% alumina) .

It also is important in gaining a better appreciation of the scope of applicant's invention to recognize that many "bulk", petroleum cracking catalysts (as opposed to "additive" type petroleum cracking catalysts) have employed alumina, silicon dioxide and clay ingredients. For example: (1) U.S. Patent 4,010,116 ("the '116 patent") teaches a, "bulk type", hydrocarbon cracking catalyst comprised of a zeolite (faujasite type) , pseudoboehmite and a synthetic mica-montmorillonite (and, optionally, a clay ingredient); (2) U.S. Patent 4,086,187 ("the •187 patent") teaches a bulk, hydrocarbon cracking catalyst formulation comprised of zeolite (faujasite type) a kaolin clay, alumina in the form of pseudoboehmite and ammonium polysilicate and (3) U.S. Patent 4,206,085 ("the '975 patent") teaches a bulk, hydrocarbon cracking catalyst comprised of zeolite in a matrix of dispersible pseudoboehmite type alumina, milled, non-dispersible pseudoboehmite type alumina, clay and silicon dioxide (and optionally, clay) . it also should be noted that the '085 patent makes it clear that some pseudoboehmites are acid-dispersible while other pseudoboehmites are not acid-dispersible. None of these patents, however, suggest chemically reacting their silica and alumina components before they are slurried together. And, indeed, applicant has established that all such prior art silica phase/alumina phase- containing bulk catalysts show no evidence that their silica component has entered the crystalline framework of their alumina component, or otherwise chemically compounded with it. Moreover, none of these silica phase/alumina phase compositions have the bottoms cracking activities that characterize applicant's BCAs. It also should be noted at this point that all such "bulk", hydrocarbon cracking catalysts are not catalyst "additives", and should not be regarded as functionally equivalent to the BCAs of this patent disclosure. Indeed, those skilled in this art will appreciate that a petroleum refinery FCC unit will not operate when charged with only "additive" type catalyst materials. Thus, for the purposes of this patent disclosure, it should be understood that the hereindescribed BCAs are to be used in proportions such that they constitute from about 1 to about 15% by weight of the entire catalyst (bulk catalyst e.g., zeolite-containing catalysts, plus all other catalyst additives) present in a petroleum cracking FCC unit. More preferably, the hereindescribed BCA's most preferably will constitute only from about 1.0 to about 10.0 weight percent of the entire catalyst inventory being used in a FCC unit. BCA Production Methods First Procedure

The first production procedure by which the BCAs of this patent disclosure can be made utilizes a "gel type reaction"; the second production procedure utilizes a "dispersion type reaction". In either case, the initial step of these procedures is to mix two ingredients - namely, a chemically compounded aluminosilicate ingredient (for example, one made according to the teachings of the '519 patent) and an acid-dispersible alumina. The aluminosilicate and the acid-dispersible alumina ingredients are mixed with sufficient liquid (e.g., water, alcohol, etc.) to form an aluminosilicate/acid-dispersible alumina slurry. The liquid needed to form such a slurry can be introduced as a separate and distinct ingredient, or it can, in whole or in part, be provided by use of acid-dispersible alumina ingredients and/or aluminosilicate ingredients that are already slurried when they are mixed with one another.

In the first production procedure, sufficient monoprotonic acid is added to the aluminosilicate/acid-dispersible alumina slurry to cause the aluminosilicate and the acid-dispersible alumina ingredients to undergo a gel type reaction. Such a reaction forms an aluminosilicate/acid- dispersible alumina/monoprotoic acid gel. Thereafter, a clay ingredient (e.g., kaolin, montmorillonite, etc.) may, be the first additional ingredient added to the aluminosilicate/acid- dispersible alumina/monoprotonic acid gel and thereby form a gel/clay mixture. The clay ingredient is preferably added to the aluminosilicate/acid-dispersible alumina/monoprotonic acid gel as a slurry rather than as a dry material. Another alumina ingredient - more specifically, an alumina that is not "acid- dispersible" (a "non-dispersible alumina") - is then added to the gel/clay mixture. Specific non- dispersible aluminas that may be used for this purpose will include all inorganic phases containing Al, O, and H. A list of representative aluminas of this type, along with their JCPDS Card Number is given in Table 1.

Optionally, a small amount of an "unreacted" silica compound also may be added to the gel/clay/non-dispersible alumina system. Most preferably, this silica will be used in a sol form that is added at the end of all of the above mixing procedures (i.e., after the non-dispersible alumina is added to the gel/clay mixture) . This "unreacted silica" component serves to improve the attrition resistance quality of the final product BCA. This unreacted silica will usually be employed in an amount such that it will constitute less than about 5 percent by weight of the final product BCA. When used, such an unreacted silica component most preferably will replace a portion of the clay component of such formulations (e.g. use of 5 percent unreacted silica in a BCA of this patent disclosure would, preferably, imply use of 5 percent less clay in that BCA) . With or without such an unreacted silica ingredient, the resulting slurry is then dried (e.g., by spray drying) and calcined to produce a BCA final product. In some cases the BCA products of this patent disclosure then may be further treated e.g., by impregnation, to associate other materials with such BCAs. Second Procedure

In applicant's second production procedure, the aluminosilicate and dispersible alumina ingredients are, as in the case of the first production procedure, initially mixed with sufficient liquid to form a slurry. And, as in the case of the first production procedure, the slurry resulting from such mixing can be created, in whole or in part, by virtue of the fact that the acid-dispersible alumina and/or the aluminosilicate ingredients already are in a slurry form when they are mixed with each other. However, in the second production procedure, the aluminosilicate/acid-dispersed alumina slurry is then mixed with only enough monoprotonic acid to "disperse" the acid-dispersible alumina particles - but not enough monoprotonic acid to cause the ingredients to form a "gel" - as in the case of the first production procedure. Use of such a lesser amount of monoprotonic acid results in an aluminosilicate/acid-dispersed alumina/monoprotonic acid dispersion system to which a clay (e.g., in the form of a kaolin clay slurry) is then added to the dispersion. Thereafter, an ammonium phosphate compound (e.g., dibasic ammonium phosphate) is then added to the aluminosilicate/acid-dispersible alumina/monoprotonic acid/clay system. Again, this ammonium phosphate ingredient may be thought of as "replacing" all or part of the non-dispersible alumina of the first production procedure. In any case, the resulting aluminosilicate/acid-dispersed alumina/acid/clay/ammonium phosphate material is then dried (e.g., by spray drying) and calcined to produce the second BCA product of this patent disclosure. And, here again, a relatively small amount (representing up to about 5 weight percent of this second BCA product) of an unreacted silica compound (preferably in the form of a sol) may be added to the slurry formulation before the drying/calcining steps are initiated.

Expressed in patent claim language, the first method for making the BCAs of this patent disclosure will comprise: (1) mixing an aluminosilicate, wherein a Siθ₂ component is chemically compounded with an acid-dispersible alumina and thereby forming an aluminosilicate/acid-dispersible alumina/liquid slurry; (2) adding sufficient monoprotonic acid to the slurry to produce a gel material from the aluminosilicate/acid-dispersible alumina/liquid slurry; (3) mixing a clay into the gel material to form a gel/clay material; (4) mixing a non- dispersible alumina into the gel clay material to produce a gel/clay/non-dispersible alumina material; (5) drying the gel/clay/non-dispersible alumina material and (6) calcining the gel/clay/non- dispersible alumina material to produce a BCA product. The second method will comprise: (1) mixing an aluminosilicate, wherein a Siθ₂ component is chemically reacted with an acid-dispersible alumina and thereby forming a aluminosilicate/acid- dispersible alumina/liquid slurry; (2) adding sufficient monoprotonic acid to the slurry to produce a dispersion material from the aluminosilicate/acid-dispersible alumina/liquid slurry; (3) mixing a clay into the dispersion material to form a dispersion/clay material; (4) mixing a phosphate-containing compound into the dispersion/clay material to produce a dispersion/clay phosphate-containing compound material; (5) drying the dispersion/clay/ammonium phosphate material and (6) calcining the dispersion/clay/ammonium phosphate material to produce a BCA product. As was previously noted, applicant believes that the reason for the highly improved bottoms cracking abilities of the BCAs prepared by the above procedures, relative to those of the prior art, revolves around the relatively large number of acid sites created on applicant's end product BCAs by use of the pre-compounded aluminosilicate ingredient in the above preparative slurries. Unfortunately, the chemical mechanisms whereby these acid sites are created in the aluminosilicate and maintained in the BCA end products are not fully understood. Nonetheless applicant's experimental work indicates that the one particular feature of the BCAs of this patent disclosure that consistently contributes to the "success" of these materials as BCAs (i.e., the ability to catalyze the cracking of high molecular weight components of petroleum without creating unduly high levels of coke) , is the presence of the aluminosilicate compounds (as opposed to two phase alumina and silica systems) in the slurry formulations that are eventually dried and calcined to make the BCA end products of this patent disclosure.

DE8CRIPTION OF PREFERRED EMBODIMENTS

Primary Ingredients

The alumina ingredients employed in the hereindescribed BCAs can be divided into three general categories:

1. The first category is comprised of those silica-containing aluminas wherein the silica ingredient is Si0₂ that is chemically compounded with an alumina ingredient to form the "aluminosilicate" component of applicant's BCAs. The aluminas used to produce such aluminosilicates are preferably acid-dispersible type aluminas in their own right. Again, such aluminosilicates are well described in the '519 patent and are sold by Condea Chemie, Brunsbuttel, Germany under their trademark SIRAL .

2. The second category of aluminas used to make the hereindescribed BCAs are acid-dispersible aluminas, i.e., aluminas capable of forming alumina dispersions and alumina gels. Acid-dispersible alpha alumina monohydrates having a pseudoboehmite structure are particularly effective acid- dispersible alumina ingredients for the hereindescribed BCAs. As was previously noted, however, not all pseudoboehmites are "acid dispersible" aluminas. For example the type B pseudoboehmites discussed in U.S. Patent 4,206,085 are not acid-dispersible. Be that as it may, other acid-dispersible aluminas suitable for the practice of this invention would include Condea Chemie's

PURAL SB , P-2 Alumina , P-3 Alumina and Disperal products. Still other suitable, acid-dispersible, alumina materials may be obtained from Vista Chemical Company in the form of their CATAPAL* alumina product. Yet another satisfactory acid- dispersible alumina for applicant's purposes is sold by LaRoche Chemical Company, Baton Rouge, Louisiana under their trade name VERSAL 900*.

3. The third category of alumina employed in applicant's BCAs is "non-dispersible aluminas", i.e., those aluminas that are not dispersible by a monoprotonic acid. Again, by way of distinction from the "acid-dispersible aluminas" noted above, "non-dispersible aluminas" have surface area characteristics that are so different from those of acid-dispersible aluminas that, for the purposes of this invention, they constitute a different kind of alumina. Applicant particularly prefers to use various aluminum trihydroxides as his non- dispersible alumina ingredient. Other useful, but less preferred, non-dispersible aluminas that may be employed in the practice of this invention include (but are not limited to) all of the inorganic phases of alumina containing Al, 0, and H of the minerals (and their synthetic counterparts) shown in the following table:

Table 1

Syn. JCPDS Card # Chemical Formula

Diaspore 5-355 AlO(OH) *Gibbsite 7-324 Al(OH)₃

Bayerite 20-0011 A1(0H)₃

Boehmite 21-1307 AIOOH 22-1119 ^A110°15-^H2°

Nordstrandite 24-0006 Al(OH)₃ Akdalaite 25-0017 (Al₂θ3)₄*H₂0 26-0025 A1(0H)₃

Gibbsite 29-0041 A1(0H)₃ 31-0018 Al₂(OH)₆-H₂0 Gibbsite 33-0018 Al(OH)₃

37-1377 _Al(OH)₃ Doyleite 38-0376 Al(OH) ₃

♦Applicant especially prefers to use a commercial product known as ATH* (sold by Solem Industries) as the non-dispersible alumina ingredient in the BCAs of this patent disclosure. This product is an aluminum trihydroxide whose crystalline structure is that of Gibbsite.

4. The monoprotonic acids used in the practice of this invention can be either inorganic or organic in nature. Formic acid, nitric acid and/or acetic acid, are particularly well suited to the hereindescribed alumina dispersion forming, or gel forming, functions described in this patent disclosure. Aside from their alumina dispersing or gelling abilities these particular monoprotonic acids are especially preferred because they decompose in applicant's calcination step and thus do not leave undesirable materials such as chlorides in the end product BCAs.

5. The clay ingredients which can be employed in applicant's process can vary considerably. For example, a wide variety of kaolinite clays (e.g., kaolin, halloysite, rectorite, etc.), montmorillinite clays (e.g. , natural montmorillinite as well as synthetic montmorillinite clays) , sepiolite clays and attapulgite clays can be readily employed. Of these, the kaolinite clays, and most particularly kaolin, are preferred - if for no other reason than its low cost and "universal" ability to bind the BCA particles of this patent without entering into undesired chemical reactions with the other materials used in making applicant's BCAs. Low sodium-containing kaolin clays, such as RC-32*, sold by the Thiele Clay Company, Wrens, Georgia, are particularly preferred when a catalytically inert clay is desired. Applicant also prefers that his clay ingredient have a surface area of at least 15 square meters per gram. Again, in certain instances applicant's BCAs may employ clay ingredients that have their own innate hydrocarbon cracking activity, e.g., halloysite, sepiolite montmorillionite and certain activated clays such as synthetic montmorillinite.

6. The phosphate-containing ingredients suitable for use in applicant's second formulation may be selected from the group consisting of monobasic phosphate compounds, dibasic phosphate compounds and tribasic phosphate compounds. Because of their ready availability and relatively low costs, monobasic ammonium phosphate, dibasic ammonium phosphate and tribasic ammonium phosphate (and/or phosphoric acid) are particularly preferred for supplying the phosphate needed for the second embodiment of there hereindescribed BCAs. That is to say that other phosphate-containing compounds can be employed in the practice of this invention, but for the most part they are, to varying degrees, much less preferred from various technical and/or comparative cost points of view. It also should be emphasized that applicant has found that mixtures of the above noted phosphate-containing compounds are particularly effective. For example, use of mixtures of monobasic ammonium phosphate and dibasic ammonium phosphate produce particularly attrition- resistant BCA products.

It also should be noted in passing that the terminology used to describe the ammonium phosphate compounds used in these processes varies somewhat in the chemical literature. For example: (1) monoammonium acid orthophosphate is often referred to as "monobasic ammonium phosphate", (2) diammonium acid orthophosphate is often referred to as "dibasic ammonium phosphate", and (3) triammonium orthophosphate is sometimes referred to as "tribasic ammonium phosphate". The terminology used in this patent disclosure may likewise vary according to these two nomenclature systems without implying a difference or distinction in the materials themselves. 7. The unreacted silica used as an optional silica ingredient of this patent disclosure is preferably obtained from silica sol ingredient(s) having silicon dioxide particles having average particle diameters of about 20 millimicrons. To this end, Du Pont Chemical's LUDOX AS-40^® product is especially well suited to the practice of this invention.

8. Other optional ingredients that may be used in applicant's BCAs would include, but not be limited to, vanadium traps (e.g. , tin, strontium titanate or sepiolite) , nickel passivators (e.g., bismuth or antimony) , density imparting materials such as barite and delaminated kaolin clay and other hydrocarbon cracking catalyst materials (e.g., zeolites) . By way of a more specific example, these BCAs might contain small proportions (e.g., no more than about 2% by weight) of zeolite particles. Larger proportions of zeolite are not preferred however because they tend to promote the formation of coke and undesired products (heavy oils) by the hereindescribed BCAs. Indeed, the most preferred BCAs of this patent disclosure will contain no zeolite component whatsoever. Other optional ingredients that may be used in the BCAs of this patent disclosure would include various volatile viscosity imparting and/or gas evolution agents such as gum arabic that are useful in making slurries having certain desired physical characteristic. These agents are described as being "volatile" because, for the most part, they are entirely driven off by the drying and calcining steps used to create the dry, BCA end products. The relative proportions of these optional ingredients, on a dry weight basis of applicant's end product BCAs, will generally be as follows:

v-Trap 0- 5%

Nickel Passivator 0- 2%

Densifiers 0-10%

Zeolite 0- 2%

Such optional ingredients may be added to the reaction slurries taught by this patent disclosure and/or, in some cases, they may be associated with the BCA by other methods known to this art such as by impregnation of BCA particles with solutions containing such ingredients.

Range of Primary Ingredients The relative proportions of the ingredients specified in this patent disclosure, unless otherwise specified, have been and will be expressed as percentages by weight of the total weight of the "solid" ingredients in the resulting (i.e., post- calcined) end product BCAs of the herein described processes. That is to say that the percentages expressed in this patent disclosure do not, for example, take into account the weight of the water, alcohol, etc. used to make up the slurries in which the solid ingredients are placed as part of the overall formulation methods. Similarly, the weight of any of the monoprotonic acids that are employed as alumina-gelling (or alumina-dispersing) agents are not considered in the dry weight proportions of applicant's end product BCAs. Be that as it may, some of the more preferred BCA formulations made according to this first production procedure, again, on a dry weight basis of the end product BCA, will be comprised of:

Most

Preferred Preferred

Ingredient Cone. Ranoe Cone.

Acid-Dispersible Alumina 15% to 30% 25%

Aluminosilicate 5% to 30% 10%

Non-Dispersible Alumina 5% to 25% 25%

Clay 30% to 60% 45%

Silica (optional) 0% to 5% 5%

Typical end product, BCAs made according to the second production procedure will, on a dry weight basis, be comprised of:

Most

Preferred Preferred

Ingredient Cone. Range Cone.

Acid-Dispersed 0% to 30% 25%

Non-Dispersible Alumina 0% to 25% 25%

Aluminosilicate 5% to 50% 10%

Clay 40% to 70% 25%

Phosphate Compound 5% to 10% 10%

Silica (optional) 0% to 5% 5%

In order to still further describe certain more preferred relative proportions of the ingredients in these BCAs, applicant has considered the alumina containing components of this patent disclosure as an overall group comprised of the three alumina types previously described. Under this system, some of the most preferred ranges of concentrations of the alumina group and clay components of the BCAs of this patent disclosure (on a dry weight basis) will be as follows.

Alumina Group 25-75%

Clay 70-20% The relative proportions, by weight percentage of the BCA end product of the aluminas within the

Alumina Group noted above would most preferably have the following range of relative proportions by weight of the final BCA products:

Dispersible Alumina 5-25% SIRAL^β 5-25%

Non-Dispersible Alumina 20-50%

Since the aluminosilicate ingredient components of each of the two BCA formulations of this patent disclosure, most preferably, will comprise from about 5 to about 30 weight percent of the respective BCA products, the remaining ingredients in these formulations (e.g., clay, non-dispersible alumina, unreacted silica and optional ingredients) will comprise from about 95 to about 70 weight percent of the resulting BCAs. When non-dispersible alumina (e.g. , in the first formulation) is employed it will preferably represent from about 5 to about 25 percent by weight of the resulting BCA product. Generally speaking higher percentages (15-25 weight percent) of such non-dispersible alumina ingredients are preferred. It also should be again noted that since applicant's aluminosilicate ingredients will be comprised of from about 0.5 to about 50.0 weight percent silica, a BCA having from about 5 to about 30 percent aluminosilicate will have a "reacted" silica component (assuming that no "unreacted silica" component is employed in the BCA) of from about 0.025 (0.5 x 5%) to about 15.0 (50.0 x 30%) weight percent of the BCA. gprav Drying and Calcining operations

The product resulting from either of applicant's slurry formulations are dried (e.g., by spray drying) and then calcined in ways well known to this art. Such calcining should be for a time period of from about 5 minutes to about 120 minutes in the temperature range of from about 800 to about 1,500 degrees Fahrenheit. The calcining typically will be carried out at about 1,000 degrees Fahrenheit for about 30 minutes. The resulting particles are most preferably calcined to form microspheroidal, fluid catalytic cracking catalyst (FCC-MS) particles in the controlled size range of from about 40 to about 250 microns, average diameter. FCC-MS particles in the 60-80 microns range, with a minimum amount of particles less than about 20 microns, are highly preferred. By way of another example, spray drying could be used to produce particles having a range of sizes such that essentially all such particles will be retained by a Standard U.S. 200 mesh screen and essentially all particles will be passed by a Standard U.S. 60 mesh screen. Other physical forms of the end products (e.g., relatively large particles or pellets) are generally less preferred - but may have utility in certain select cases e.g., where the BCA end product is not used in a fluidized catalytic process but rather in a so-called "fixed bed" system. It also should be specifically noted that the temperature and residence times needed to calcine applicant's BCAs to their final products can be supplied by a FCC unit into which uncalcined, or partially calcined materials (e.g., those taken from applicant's spray drying step) are introduced for calcination. For example spray dried particles of applicant's BCA formulation can be introduced into the FCC unit's catalyst regenerator where temperatures usually range from about 1100°F to about 1350°F.

Optional Drying Procedures

It should also be noted that in addition to a spray drying step, applicant's overall process may be enhanced by use of a separate and distinct drying step that is carried out after the drying naturally occurring from the spray drying step. Such additional drying may serve to better "freeze" the ingredients in the homogeneous state in which they originally existed in the slurry. That is to say that the "solid" particle product of applicant's spray drying step may be, as an optional process step, desiccated or dried in a manner other than the drying accomplished by the spray drying. This additional drying will further serve to remove any remaining traces of the liquid medium which may be still present in the interstices of the particles and/or associated with the particulate product of the spray drying step (e.g., associated as water of hydration) . Drying times for this distinct drying step will preferably take from about 0.2 hours to about 24 hours at temperatures which preferably range from about 200°F to about 500°F (at atmospheric pressure), but in all cases, at temperatures greater than the boiling point of the liquid medium employed (e.g., greater than 212°F in the case of water) . Thereafter the dried materials may be transferred to a calciner where they are calcined under controlled conditions; or the dried particles may be transferred to a FCC unit (or fixed bed unit) where they are calcined by the temperature conditions existing in such FCC unit. Exemplary Preparations

The following specific examples serve to illustrate certain preferred preparative procedures of this patent disclosure.

Example 1

A slurry consisting of 270 grams of Condea

Pural SB and 71 grams of Condea Siral 5 in 2159 grams of water was prepared. To this slurry 68 grams of formic acid was added; the mixture was then stirred until it formed a gel. To this gel, 833 grams of a 60% weight kaolin clay slurry was added; this was followed by the addition of 893 grams of a 28% slurry of ATH. Upon thorough mixing, the resulting material was spray dried. The spray dried particles were then calcined for one hour at 1000°F to produce BCA particles suitable for use in a FCC unit.

Example 2

A mixture of 333 grams of Condea Pural SB and 333 grams of Condea Siral 5 were added to 1000 milliliters of water containing 15 grams of acetic acid. The mixture was stirred until it formed a uniform dispersion of colloidal alumina particles. To this dispersion 840 grams of a 60% clay slurry was added. This was followed by addition of 17.5 grams of dibasic ammonium phosphate. This, in turn, was followed by the addition of 1133 milliliters of water in order to make a pumpable slurry. The slurry was then spray dried. The spray dried particles were then calcined for one hour at 1000°F to produce a BCA end product.

In both examples 1 and 2, Condea Pural SB* served as the binder or "glue". In Example 2, however, both aluminas are simply dispersed, that is to say that only a small amount of acid was used so that the alumina would not form a gel. In this case the clay-phosphate acted as the binder.

Example 3 A slurry consisting of 341 grams of Condea

Siral 0.4* in 2159 grams of water was prepared. To this slurry, 68 grams of formic acid was added; the mixture was stirred until it formed a gel. To this gel, 833 grams of 60% by weight clay slurry was added; this was followed by addition of 893 grams of 28% slurry of ATH. This mixture was spray dried. The spray dried particles were then calcined at

1000°F.

Example 4 A slurry consisting of 341 grams of Condea

Siral 0.8* in 2159 grams of water was prepared. To this slurry, 68 grams of formic acid was added; the resulting mixture was stirred until it formed a gel. To this gel, 833 grams of a 60% weight clay slurry was added; this was followed by the addition of 893 grams of 28% slurry of ATH. This mixture was spray dried. The spray dried particles were then calcined for one hour at 1000°F.

Example 5 A slurry was prepared by adding 374.4 grams of

Condea Pural SB* alumina to 1384 grams of water. To this slurry 56.2 grams of formic acid was added. The mixture was stirred until it formed a gel. To 1512 grams of this gel, a slurry consisting of 573.5 grams of halloysite clay in 1673 grams of water was added. The slurry was spray dried. The spray dried particles were then calcined for one hour at 1000°F. Example 6

To 1000 milliliters of water containing 15 grams of acetic acid 666 grams of Condea Siral 0.8* was added. The mixture was stirred until it formed a uniform dispersion of colloidal alumina particles. To this dispersion, 840 grams of a 60% clay slurry was added. This was followed by the addition 17.5 grams of dibasic ammonium phosphate. This, in turn, was followed by addition of 1133 milliliters of water in order to make a pumpable slurry. The slurry was spray dried. The spray dried particles were then calcined for one hour at 1000°F.

While applicant's invention has been described with respect to various theories, specific examples and a spirit which is committed to the concept of use of an aluminosilicate wherein the occurrence of a chemical reaction between alumina and silica ingredients has taken place before the resulting aluminosilicate is slurried with the other BCA ingredients, the full scope of this invention is defined by the claims of this patent disclosure. Therefore, what is claimed is:

Claims

1. A bottoms cracking additive comprising: an aluminosilicate compound wherein a Siθ2 component is chemically compounded with an alumina component, an acid-dispersible alumina, a clay and a non- dispersible alumina.

2. The bottoms cracking additive of claim 1 wherein the aluminosilicate compound contains from about 0.5 to about 50.0 weight percent Siθ₂-

3. The bottoms cracking additive of claim 1 wherein the aluminosilicate is prepared by mixing, in an aqueous medium, a C₂ to C₂₀ alkoxide hydrolyzed with water and purified by ion exchange with a silicic acid compound.

4. The bottoms cracking additive of claim 1 comprised of from about 5 to about 30 weight percent aluminosilicate, from about 15 to about 30 weight percent acid-dispersible alumina, from about 5 to about 25 weight percent of non-dispersible alumina and from about 30 to about 60 weight percent clay.

5. The bottoms cracking additive of claim 1 wherein the aluminosilicate compound comprises from about 10 to about 25 weight percent of the bottoms cracking additive.

6. The bottoms cracking additive of claim 1 that further comprises an unreacted silica component that constitutes less than about 5.0 percent by weight of the bottoms cracking additive.

7. The bottoms cracking additive of claim 1 that further comprises a vanadium trap component in a concentration that is less than about 2.0 percent by weight of the bottoms cracking additive.

8. A bottoms cracking additive comprising: an aluminosilicate compound wherein a Siθ₂ component is chemically compounded with an alumina component, an acid-dispersible alumina, a clay and a phosphate- containing compound.

9. The bottoms cracking additive of claim 8 wherein the aluminosilicate compound contains from about 0.5 to about 50.0 weight percent Siθ2-

10. The bottoms cracking additive of claim 8 wherein the aluminosilicate is prepared by mixing, in an aqueous medium, a C to C₂₀ alkoxide hydrolyzed with water and purified by ion exchange with a silicic acid compound.

11. The bottoms cracking additive of claim 8 comprised of from about 5 to about 30 weight percent aluminosilicate, from about 15 to about 30 weight percent acid-dispersible alumina, from about 5 to about 25 weight percent of a phosphate-containing ingredient and from about 30 to about 60 weight percent clay.

12. The bottoms cracking additive of claim 8 wherein the aluminosilicate contains from about 0.5 to about 25.0 weight percent Siθ₂«

13. The bottoms cracking additive of claim 8 that further comprises an unreacted silica component that constitutes less than about 5.0 percent by weight of the bottoms cracking additive.

14. The bottoms cracking additive of claim 8 that further comprises a vanadium trap component in a concentration that is less than about 2.0 percent by weight of the bottoms cracking additive.

15. A method of cracking high molecular weight components of petroleum, said method comprising adding separate and distinct particles of a bottoms cracking additive (comprised of an aluminosilicate compound wherein a Siθ₂ component is chemically compounded with an alumina component, an acid- dispersible alumina, a clay and non-dispersible alumina) to a fluid catalytic cracking unit utilizing separate and distinct particles of a bulk, zeolite-containing, hydrocarbon cracking catalyst, in proportions such that the separate and distinct particles of the bottoms cracking additive constitute from about 1 about 15 weight percent of all catalyst in the fluid catalytic cracking unit.

16. The method of claim 15 wherein the aluminosilicate compound contains from about 0.5 to about 50.0 weight percent Siθ2-

17. The method of claim 15 wherein the aluminosilicate compound contains from about 0.5 to about 25.0 weight percent Siθ2«

18. The method of claim 15 wherein the bottoms cracking additive is comprised of from about 5 to about 30 weight percent aluminosilicate, from about 15 to about 30 weight percent acid-dispersible alumina, from about 5 to about 25 weight percent of non-dispersible alumina and from about 30 to about 60 weight percent clay.

19. The method of claim 15 wherein the bottoms cracking additive further comprises an unreacted silica component that constitutes less than about 5.0 percent by weight of the bottoms cracking additive.

20. A method of cracking high molecular weight components of petroleum, said method comprising adding separate and distinct particles of a bottoms cracking additive (comprised of an aluminosilicate compound wherein a Siθ₂ component is chemically compounded with an alumina component, an acid- dispersible alumina, a clay and a phosphate- containing compound) to a fluid catalytic cracking unit utilizing separate and distinct particles of a bulk, zeolite-containing, hydrocarbon cracking catalysts in proportions such that the separate and distinct particles of the bottoms cracking additive constitute from about 1 to about 15 weight percent of all catalyst in the fluid catalytic cracking unit.

21. The method of claim 20 wherein the aluminosilicate compound contains from about 0.5 to about 50.0 weight percent Siθ₂»

22. The method of claim 20 wherein the aluminosilicate compound contains from about 0.5 to about 25.0 weight percent Siθ₂-

23. The method of claim 20 wherein the bottoms cracking additive is comprised of from about 5 to about 30 weight percent aluminosilicate, from about 15 to about 30 weight percent acid-dispersible alumina, from about 5 to about 25 weight percent of a phosphate-containing ingredient and from about 30 to about 60 weight percent clay.

24. The method of claim 20 wherein the bottoms cracking additive further comprises a silica component that is less than about 5.0 percent by weight of the bottoms cracking additive.

25. A method for making a bottoms cracking additive, said process comprising:

(1) mixing an aluminosilicate, wherein a Siθ2 component is chemically reacted with an alumina component, with a dispersible alumina and thereby forming a aluminosilicate/dispersible alumina/liquid slurry;

(2) adding sufficient monoprotonic acid to the slurry to produce a gel material from the aluminosilicate/dispersible alumina/liquid slurry;

(3) mixing a clay into the gel material to form a gel/clay material;

(4) mixing a non-dispersible alumina into the gel/clay material to produce a gel/clay/non- dispersible alumina material;

(5) drying the gel/clay/non-dispersible alumina material and

(6) calcining the gel/clay/non-dispersible alumina material to produce a BCA product.

26. The method of claim 25 wherein the aluminosilicate compound contains from about 0.5 to about 50.0 weight percent Siθ2«

27. The method of claim 25 wherein the aluminosilicate compound contains from about 0.5 to about 25.0 weight percent Siθ2-

28. The method of claim 25 wherein the bottoms cracking additive is comprised of from about 5 to about 30 weight percent aluminosilicate, from about 15 to about 30 weight percent acid-dispersible alumina, from about 5 to about 25 weight percent of non-dispersible alumina and from about 30 to about 60 weight percent clay.

29. The method of claim 25 wherein the aluminosilicate is prepared by mixing, in an aqueous medium, a C2 to C20 alkoxide hydrolyzed with water and purified by ion exchange with a silicic acid compound.

30. The process of claim 25 that further comprises adding a vanadium trap component in a concentration that is less than about 2.0 percent by weight of the bottoms cracking additive.

31. The process of claim 25 that further comprises adding an unreacted silica component that constitutes less than about 5.0 percent by weight of the bottoms cracking additive.

32. A process for making a bottoms cracking additive, said process comprising:

(1) mixing an aluminosilicate wherein a Siθ2 component is chemically compounded with an alumina component, with a dispersible alumina and thereby forming a aluminosilicate/dispersible alumina/liquid slurry;

(2) adding sufficient monoprotonic acid to the slurry to produce a dispersion material from the aluminosilicate/dispersible alumina/liquid slurry;

(3) mixing a clay into the dispersion material to form a dispersion/clay material; (4) mixing a phosphate-containing compound into the dispersion/clay material to produce a dispersion/clay phosphate-containing compound material;

(5) drying the dispersion/clay phosphate- containing compound material and

(6) calcining the dispersion/clay phosphate-containing compound material to produce a

BCA product.

33. The process of claim 32 wherein the aluminosilicate compound contains from about 0.5 to about 50.0 weight percent Siθ2«

34. The process of claim 32 wherein the aluminosilicate is prepared by mixing, in an aqueous medium, a C2 to C20 alkoxide hydrolyzed with water and purified by ion exchange with a silicic acid compound.

35. The process of claim 32 that further comprises adding a vanadium trap component in a concentration that is less than about 2.0 percent by weight of the bottoms cracking additive.

36. The process of claim 32 that further comprises adding a silica component that constitutes less than about 5.0 percent by weight of the bottoms cracking additive.