WO1995030725A1

WO1995030725A1 - Improved metals tolerant zeolitic catalyst for catalytically cracking metal contaminated oil feedstocks

Info

Publication number: WO1995030725A1
Application number: PCT/US1995/005256
Authority: WO
Inventors: Glenn W. Dodwell; Bruce A. Lerner; John M. Macaoay; Beth Ann Smith; Paul R. Suitch; Gerald M. Woltermann
Original assignee: Engelhard Corporation
Priority date: 1994-05-10
Filing date: 1995-04-26
Publication date: 1995-11-16
Also published as: AU2367995A

Abstract

A cracking catalyst comprising a molecular sieve dispersed in a matrix comprising kaolin clay, synthetic silica-alumina, particulate low surface area macroporous gamma alumina derived from peptizable crystalline boehmite and magnesium phosphate. The catalyst is used to crack hydrocarbon feedstocks high in nickel and vanadium.

Description

IMPROVED METALS TOLERANT ZEOLITIC CATALYST FOR CATALYTICALLY CRACKING METAL CONTAMINATED OIL FEEDSTOCKS

Field of the Invention

This invention relates to catalysts useful for cracking heavy hydrocarbon feedstocks, such as resids, that contain high levels of nickel and vanadium contaminants.

The catalysts are composed of a crystalline zeolitic molecular sieve included in an inorganic matrix comprising a source of phosphate, preferably magnesium phosphate and low surface area macroporous gamma alumina derived from low surface area macroporous crystalline boehmite. The catalysts are characterized by a spectrum of desirable properties including superior metals tolerance with respect to both nickel and vanadium.

Background

In a fluid catalytic cracking process, hydrocarbon feed material is cracked at elevated temperature in a reactor containing a fluidized catalyst. The predominant type now used in refineries is the zeolitic catalyst. Catalytic cracking may also be carried out in a so-called "moving bed" unit wherein catalyst pellets move downward through rising, hot gaseous hydrocarbons. As the cracking process continues the activity of the catalyst gradually deteriorates. Fluid catalysts are typically removed, regenerated in a regenerator to burn off coke and provide heat for subsequent cracking reactions and returned to the reactor. In the regeneration step, carbonaceous materials deposited on the catalyst during cracking are burned off with air. Typically the process may be run continuously with catalyst being drawn off continuously from the reactor, regenerated and returned to the reactor along with fresh catalyst added to make up for stack losses or to boost equilibrium activity.

The catalyst cannot be regenerated to the original activity level indefinitely, even under the best of circumstances, i.e., when accretions of coke are the only cause for reduced activity. When activity has deteriorated sufficiently zeolitic catalysts must be discarded.

Loss of activity or selectivity of the catalyst may also occur if certain metal contaminants arising principally from the hydrocarbon feedstock, such as nickel, vanadium, iron, copper and other heavy metals, deposit onto the catalyst. These metal contaminants are not removed by standard regeneration (burning) and contribute markedly to undesirably high levels of hydrogen, dry gas and coke and reduce significantly the amount of gasoline that can be made. Contaminant levels are particularly high in certain feedstocks, especially the more abundant heavier crudes. As oil supplies dwindle, successful economic refining of these heavier crudes becomes more urgent. In addition to reduced amounts of gasoline, these contaminant metals contribute to much shorter life cycles for the catalyst and an unbearably high load on the vapor recovery system. Deposited nickel species have an intrinsic dehydrogenation activity which leads to the formation of coke and gas, two undesirable products. On the other hand, vanadium interacts with the molecular sieve component of the catalyst and upon doing so destroys the crystallinity of the sieve. This leads to a loss of catalytic activity and to the formation of certain silica-alumina species which tend to promote the formation of coke and gas. Also, vanadium has an intrinsic dehydrogenation activity which leads to unfavorable selectivity. The increased expense of refining metals contaminated feedstocks due to the aforementioned factors lays a heavy economic burden on the refiner. Thus, much effort has been spent in finding means to modify the catalyst or feedstock in such a way as to passivate the aforementioned undesirable effects of the metal contaminants.

One method disclosed in US Patent Nos. 3,162,595; 3,162,596 and 3,165,462 is to remove the metals from the catalyst after the catalyst exits the reactor for regeneration. This is accomplished by a so-called demetallization process involving such steps as acid- washing, chlorinating, etc. to convert the metals on the catalyst to dispersable or volatile forms and separating the dissolved or dispersed metal poisons from the catalyst. This technology has not been widely used, presumably because of the expense involved. Another method is to passivate the metal contaminants, or more specifically, to ameliorate the undesirable effects thereof, by adding an antimony-based passivating agent to the fresh catalyst, to the feedstock directly to impregnate the catalyst, or to regenerated catalyst, or to use cracking catalyst fines which are then added to the process. These passivating agents are metal compounds exemplified by an antimony tris (0,0- dihydrocarbylphosphorodithioate) disclosed in the following US patents to McKay et al: Nos. 4,207,205; 4,031,002 and 4,025,458. The use of antimony compounds on catalyst fines is disclosed in US Patent No. 4,216,120 to Nielsen et al., and cracking catalyst is disclosed in US Patent No. 3,711,422 to Johnson.

Other passivating agents have also found utility for cracking catalysts. Bismuth and manganese compounds are disclosed by Readal et al. in US Patent No. 3,977,963, and by McKinney et al. in US Patent No. 4,083,807; and use of low levels of boron compounds is disclosed in US Patent No. 4,192,770 to Singleton. Tin compounds are disclosed in US Patent No. 4,040,945 to McKinney, and tin in combination with antimony is disclosed in US Patent No. 4,255,287 to Bertus, et al. A thallium supplying material is disclosed in US Patent No. 4,238,367 to Bertus et al. for passivation of contaminant metals.

Treating non-zeolitic cracking catalysts with phosphorus compounds is also known. For example US Patent No. 2,758,097 to Doherty et al. discloses addition of P₂0₅ or compounds convertible to P₂0₅ to reduce the undesirable effects of nickel on nickel-poisoned siliceous cracking catalysts. US Patent No. 2,977,322 to Varvel et al. discloses a method for deactivating metal poisons by contacting a clay catalyst with phosphorus in combination with chlorine compounds. US Patent No. 2,921,018 to Helmers et al. discloses treating acid-activated clay with compounds of phosphorus to convert metallic poisons to their corresponding phosphorus compounds, thereby deactivating the contaminant metals. These patents do not recognize that adding certain phosphorus compounds, particularly phosphoric acids, can destroy the zeolite in zeolitic cracking catalysts after heat treatment.

Other methods of incorporating phosphorus into or onto cracking catalyst have been tried. US Patent Nos. 4,158,621 and 4,228,036 both to Swift, et al. disclose a silica- alumina-aluminum phosphate matrix incorporating a zeolite having cracking activity.

In US Patent No. 3,867,279 to Young a zeolite cracking catalyst containing 1-30% P₂0₅ for improved crush strength is disclosed. No utility of phosphorus for metals passivation is recognized in this patent.

US Patent No. 4,975,180 (Eberly) is directed to a catalytic cracking process in which phosphorous-containing alumina particles are separately admixed with zeolite cracking catalyst particles. In US 4,977,122 (Eberly) the phosphorus-containing alumina particles are a component of the particles that contain the zeolite. As background to these inventions, it had been conventional to include discrete alumina particles in the matrix of zeolitic cracking catalysts to assist in bottoms conversion and to increase the resistance of the zeolite to nitrogen and metals. It had also been known that the presence of the alumina in the catalyst particles also increased coke made in the fluid catalytic cracker. US 4,567,152 (Pine) discloses the impregnation of alumina particles with certain phosphorus-containing compounds to lower the coke. Commonly assigned US 4,430,199 (Brown) teaches addition of certain phosphorus compounds such as an ammonium hydrogen phosphate to passivate metals, the phosphorus compound being added to oil feed or to catalyst particles.

The Invention The invention relates to improvements in the type of cracking catalysts which comprise a spray dried zeolitic molecular sieve component dispersed in an inorganic matrix component. In accordance with this invention, the matrix comprises a specific type of alumina, namely, particulate low surface area macroporous gamma alumina obtained from a low surface area particulate fully-peptizable crystalline boehmite precursor. Optionally, the matrix includes kaolin clay and gamma alumina derived from particulate gibbsite. The binder is preferably silica-alumina derived from a silica sol. The matrix also includes magnesium phosphate. A unique feature of the catalyst is that the pore size characteristics of the specific alumina reactant (crystalline boehmite) is essentially unchanged during * processing. Another feature is that phosphate is incorporated as a poorly soluble magnesium phosphate. 5 The vanadium passivation is superior to that of magnesium phosphate without the particular form of alumina employed in practice of the invention and the nickel passivation of this product is greater than the passivating power of a comparable amount of this form of alumina alone. 10 This suggests a relationship of mutual chemical interaction. The magnitude of the trapping ability of the catalyst for vanadium was unexpected.

Description of the Preferred Embodiments At least a portion of the particulate alumina used in

.5 producing catalysts of this invention must be a peptizable crystalline boehmite having large pores and low surface area. Typically, pores are centered at about 200 Angstrom units (radius), i.e., at least about 50%, preferably 70% - 100%, of the pore volume is contained in pores having radii

:0 from 100 to 300 Angstrom units. Surface area (BET, nitrogen) of the crystalline boehmite (as well as the gamma alumina conversion product) is below 150 m²/g, preferably below 125 m²/g- and most preferably below 100 m/g, e.g. 60- 80 m7g.

:5 Following are typical properties of a fully peptizable crystalline boehmite used in practice of the invention. A1₂0₃ wt% 99 0 min. (ignited)

Carbon " 0 5 max.

Si0₂ " 0 015 max.

Fe₂0₃ 0 015 max.

Na₂0 " 0 005 max.

Surface Area (m²/g) 80 (before calcination)

Pore volume, cc/g 70% in pores having radii from 100 to 300 Angstrom units

Particle size distribution wt% less than 25 microns 15.0 max. wt% less than 45 microns 35.0 max. wt% greater than 90 microns 20.0 max.

Total volatiles 20 wt% max.

Pore size diameter 150-200 Angstroms

Monoprotic acids, preferably formic, can be used to peptize the crystalline boehmite. Other acids that can be employed to peptize the alumina are hydrochloric and acetic.

During production, spray dried microspheres containing crystalline boehmite in the matrix are calcined. As a result of calcination, the crystalline boehmite is converted to a macroporous gamma alumina but micropores are essentially unchanged. Thus, the BET surface area of this material only increases marginally, e.g., increases from 80 m²/g to 100 m²/g. The matrix may also contain gamma alumina derived from low surface area gibbsite, e.g., gibbsite having a BET surface area of about 100 m²/g. Calcination converts gibbsite to high surface area gamma alumina, e.g., alumina having a surface area of about 250- 300 m²/g. Gibbsite is included as an optional reactant when it is desirable to provide a catalyst with a high surface area alumina component with superior ability to crack bottoms.

Conventional silica hydrosol (silica-alumina) binders, 5 kaolin and molecular sieve zeolites are used in producing catalysts of the invention. Conventional relative proportion of these materials can be used.

Suitable silica hydrosol binders (sol) can be prepared by procedures described in US 3,957,668. These sols are

LO frequently referred to as alum buffered silica sols. Crystalline boehmite alumina must be introduced in peptized form. Techniques known in the art can be used. A high solids dispersed slurry of kaolin clay is usually used in formulating the catalyst. Solids of these kaolin slurries

-5 are typically 50-70%; pH is usually in the range of 5 to 7.

The hardness of the final spray dried catalyst is a function of the strength of the binder. The strength of the binder obtained using a silica sol decreases with increasing pH. The attrition resistance of the catalyst may

:0 be directly correlated with the pH conditions to which the sol binder is exposed.

Suitable zeolites for use in the process of the present invention are any of the naturally occurring or synthetic crystalline zeolites used in cracking catalysts.

5 Preferably, the zeolite is a Y-type zeolite. The term ^πY- type zeolite" as used herein a zeolite having a silica to alumina mole ratio of at least about 3, the structure of faujasite and uniform pore diameters ranging from about 6 to about 15 Angstroms. Most preferably, the zeolite has a unit cell size below 24.7 Angstroms. Especially preferred are zeolites having unit cell size below about 24.5 Angstroms. These zeolites are known as "stabilized" or "ultrastable" forms of Y zeolite. The zeolites as produced or found in nature normally contain an alkali metal cation such as sodium and/or potassium and/or an alkaline earth metal cation such as calcium and magnesium. It is conventional in the art to decrease the alkali metal content of the zeolite to less than 1 wt%, preferably less than 0.5 wt% by exchange with ammonium ions. In some cases cations of rare earth metals are introduced.

It is within the scope of the invention to incorporate other materials in the cracking catalysts such as precious metal based carbon monoxide oxidation promoters or ZSM-5 zeolite to improve octane.

Following are preferred components useful in practice of the invention. All proportions are reported on a dry weight basis.

20-40%, preferably 30%, USY (ultrastable Y)

10-30%, preferably 20%, silica hydrosol (binder)

Optional 5% recycle (undersized zeolitic spray dryer product from previous production)

2-15%, preferably 5% gibbsite

0.5 to 5%, magnesium phosphate Mg₃(P0₄)₂ added as Mg₃(P0₄)₂.8H-0

2-25%, preferably 12%, fully peptizable crystalline boehmite

5-40%, preferably about 25%, kaolin clay Nominal surface area for a suitably finished catalyst is in the range of 100 to 300 m²/g, preferably 200 to 225 m²/g, e.g., 210 m²/g, with a zeolite surface area in the range of 100 to 180 m²/g, e.g., 150 m²/g. Nominal rare earth

5 level is 0 to 1.2 wt% on catalyst and nominal sodium level is a maximum of 0.2 wt% as Na₂0. Final catalysts typically contain 0.85 wt% phosphorous (analyzed as P₂0₅) and 0.01 to 2.5 wt% MgO.

In practice of the invention on a continuous basis, L0 USY molecular sieve and recycle are mixed together prior to the run and milled in a media mill to a particle size of approximately 2 microns average. Gibbsite, milled to a 2 micron average particle size, is slurried in water to 20- 25% solids as A1₂0₃. Dry milling will increase BET surface

.5 area; for example, gibbsite having an average size appreciably above 2 microns and surface area of 15-16 m²/g may have a surface area of about 100 m²/g after milling. An aqueous slurry of Mg₃(P0₄)₂.8H₂θ is prepared. This slurry can be added to the slurry of ground gibbsite or the slurry of

0 magnesium phosphate can be incorporated with the other components at any point, prior to spray drying. When magnesium phosphate is mixed with the slurry of gibbsite, the total slurry makes up 6.5% of the spray dryer feed. It

« is adjusted after preparation to a pH between 5.0 to 5.5

5 with formic acid. Using other sequences of reagent additions, the pH of the slurry gibbsite is always adjusted below 5.0 by addition of formic acid. A peptized slurry of crystalline boehmite alumina is prepared by slurrying the alumina in water and adjusting pH under stirring to 2.6-2.8 with formic acid. The peptized slurry is allowed to sit quiescently prior to addition to a "matrix tank" . Kaolin clay as a 65 wt% dispersed slurry is used "as is". The pH of the kaolin slurry is 7-8. Alum buffered silica hydrosol is prepared in a conventional manner. The resulting sol is metered to the "matrix" tank operated with a high shear mixer along with the other constituents and the ingredients are thoroughly mixed in the matrix tank prior to feeding the slurry to the spray dryer. Residence time in the mixer is typically less than 30 minutes. The pH of the spray dryer feed is between 3.1 and 3.3.

The spray dried product is then reslurried and processed. This is referred to in the art as "catalyst workup" .

The processing can also be carried out on a batch scale. In one method, the silica sol is prepared and placed under a high shear mixer. To it are added the following components: kaolin clay, peptizable crystalline boehmite, gibbsite, powdered molecular sieve, preferably ultrastable Y and phosphate salt. The resulting slurry should have a final pH no greater than about 3.5. Acid such as formic or similar may be added to the slurry during preparation to help control pH. The well mixed slurry is then spray dried.

In a semi-batch preparation, the sol is prepared and placed in a pot. All the other components are prepared and placed in a separate vessel. The contents of the two vessels are pumped at a selected ratio spray dried. Fluid catalytic cracking of the present invention can be used in any conventional FCC catalytic cracking unit using typical catalytic conditions. The catalysts are of especial benefit when used to crack feeds having a high 5 content of metal contaminants, e.g., 2,000 to 10,000 ppm nickel and 2,000 to 10,000 ppm vanadium. While the invention has been described with especial reference to fluid cracking catalysts, known technology can be used to provide similar catalyst combination in pellet or spherical

-0 form suitable for use in moving bed (e.g., TCC0 units) . Catalysts of the invention can be used to crack conventional hydrocarbon feeds used in catalytic cracking, e.g., naphthas, gas oils and residual oils.

MAT testing in the presence of contaminant metals such

.5 as nickel and vanadium show that catalysts of this invention are superior in both activity and selectivity to a catalyst prepared with either magnesium phosphate or crystalline boehmite alone (where magnesium phosphate can be as high as 5% and crystalline boehmite as high as 12%)

0 and in addition to a catalyst containing neither. Specifically, both the coke and hydrogen make are decreased and the gasoline yield is increased.

The clear advantage of this catalyst is its superior metals trapping capability. The trapping capability leads

5 to favorable selectivity consequences and aids in maintaining favorable catalyst activity maintenance extending the usable lifetime of the catalyst. A catalyst of this invention was prepared by combining the below listed materials in a particular process. Two mixtures were prepared separately and subsequently combined with vigorous agitation and then spray dried. One mixture, 284 pounds of a standard silica sol binder was prepared in accordance with the methods taught by US 3,957,668. In a separate agitated vessel, the following materials were combined: 71 pounds of a 70% solids slurry of hydrous kaolin and 161 pounds of a 29 wt.% aqueous slurry of USY. To this vessel was then added 57.5 pounds of an aqueous slurry of 20% gibbsite (previously ground to 2 microns APS). Magnesium phosphate, 11 pounds of Mg₃(P0₄)₂.8H₂0, was then slowly added. After mixing this slurry was pumped to a Cowles mixer where it was blended under high shear conditions. During the high shear blending, 63 pounds of macroporous peptized crystalline boehmite slurry (nominal 22% solids) was added. When necessary to prevent flocculation of the clay, a dispersant (ammonium polymethyl methacrylate) was added.

Wt.% USY (UCS 24.55A, Na₂0 = 3%) 30

Silica Hydrosol 20

Gibbsite 5

Mg₃P0₄ 5

Macroporous crystalline boehmite 8 Water washed Kaolin Clay 32

The binder and zeolite slurry were then metered, combined and pumped to a spray drier. 1000 grams of the -15- spray drier product was slurried with an equal weight of water and filtered in a Buchner funnel. 1000 grams of 1 molar ammonium sulfate solution was then contacted with the filtered product with occasional mixing during filtration. After the majority of the filtrate was removed, two 1000 gram solutions of IM ammonium sulfate were similarly contacted with the product in the Buchner funnel. The catalyst was then washed with five 1000 gram solutions of hot tap water with similar mixing on the Buchner funnel. The wet filtered product was dried overnight at 100°C in a drying oven. The product was then combined with a rare earth nitrate solution whose concentration was adjusted to achieve 1.2% REO on the catalyst. The catalyst was then dried overnight and then calcined at 1000°F. The catalyst generated by the aforementioned procedure had the properties listed below:

% Sio₂ 58.1

% A1₂0₃ 38. 0

% Na₂0 0.20

% MgO 0.12

% Tio₂ 0.26

% P₂0₅ 0.85

% REO 1. 11

TSA m²/g 258

MSA m /g 106

ZSA m²/g 152

Nitrogen Pore Volume (cc/g) 20-100 A Diameter 0.0610

100-600 A Diameter 0.0366 Mercury Pore Volume (cc/g) 40-600 A Diameter 0.0969 600-2OK A Diameter 0.2294

Unit Cell Size 24 . 50A

Attrition Values

Roller 29.9

EAI 1. 35 The Roller attrition test is described in US

5,082,814, Stockwell, et al. US 4,493,902, Brown, et al., describes the EAI test. The terms MSA (matrix surface area) , ZSA (zeolite surface area) and TSA (total surface area) are defined in US 5,023,220, Dight, et al.

The results of the following tests demonstrate critical features of this invention.

In accordance with the present invention, the phosphorus-containing compound (magnesium phosphate) is added at the time of catalyst formation, precluding exclusive interaction with alumina prior to forming the catalyst. Prior art exemplified by US 4,760,040 (Sato) and US 4,977,122 (Eberly) disclose adding a phosphorus- containing material to alumina as a discrete step and thereafter adding the phosphorus-containing alumina to the catalyst as a discrete catalyst component. Following are details of the preparation of a USY catalyst employing the prior art teaching of pretreating alumina with the phosphorus compound. Five hundred (500g) of a high pore volume low surface area crystalline boehmite was impregnated to incipient wetness with a solution prepared by dissolving 80g of monoammoniumhydrogen phosphate (MAP) in 200g of water. The impregnated alumina was dried overnight, calcined at 1050°F for 1 hour and ground to a fine powder.

Two hundred and fifty (250g) of the above treated alumina was slurried in 750g of water and added to a slurry of 5600g of silica sol (10.7 wt% Si02) , 3225g of a 30% (volatile-free weight) USY slurry, and 2060g of a 60%

(volatile-free weight) kaolin slurry. The mixture was stirred for 5 minutes and spray dried. The spray dried microspheres were water washed and exchanged with a 10% ammonium sulfate solution to a Na₂0 level of less than 0.4 wt% on catalyst. The exchanged catalyst was washed with hot water to remove sodium sulfate and exchanged with a rare earth nitrate solution (27.5 wt% REO) to a REO level of

1.25 wt% on catalyst. The rare earth exchanged catalyst was dried overnight.

A sample of the catalyst prepared as described above by pretreating alumina with a phosphorus-containing compound (designated "P treated Al") was subjected to catalytic cracking using 3000V/3000Ni. The results were compared with those obtained using a representative catalyst of the invention (magnesium phosphate added at the time of catalyst formation using crystalline alumina) and ion-exchanged as described for the test catalyst.

The results shown in Table 1 demonstrate that by adding a phosphorus-containing compound as a discrete step and then incorporating the phosphorus-containing alumina to the catalyst as a discrete component, the results were poor compared to those obtained by practice of this invention. Table l:3000V/3000Ni Sample Conv. (c/o=5) Coke H2 Gasoline

Cat. of Invention 60 6.20 0.76 47.4

P treated Al 51 6.73 0.92 46.7 Tests were also carried out using aluminas having pore structure different from the crystalline boehmite alumina useful in practice of the present invention.

Three thousand two hundred and twenty-five (3225)g of a 30% (volatile-free weight) USY slurry was mixed with 5600g of silica sol (10.7 wt% Si02) , 92g of (Mg)3(P04)2.8 H20 (65% by weight magnesium phosphate) , 325g of a high surface area, small pore size, pseudoboehmite commercially sold as Versal^® 250 alumina (74% A1₂0₃) in 1425g of water, and 1870g of a 60% (volatile-free weight) kaolin slurry. The slurry was spray dried and the resultant microspheres exchanged in the same manner as used to prepare the "P treated Al" and catalyst of the invention (Table 1) .

Another sample was prepared in the identical manner except 369g of gibbsite in 63Og of water was substituted for the slurry Versal^® 250 alumina. Gibbsite has a small pore size and a high surface area after heat activation such as calcination.

The results, summarized in Table 2, show the catalyst of the invention produced significantly less coke and hydrogen than catalysts prepared with magnesium phosphate but using aluminas outside the scope of this invention. Table 2;3000V/3000Ni

Sample/

Source of Alumina Conv. Coke H2 Gasoline

Invention/ 56 6.18 0.78 47.4

Crystalline Boehmite

Pseudoboehmite 54 7 .71 1. 03 45.7

Gibbsite 54 7.29 1.01 46. 0

Tests were carried out with an alumina of the invention but using a source of phosphorus (monoammoniumhydrogen phosphate) other than magnesium phosphate to demonstrate the importance of the source of phosphorus. The preparation using monoammoniuirihydroc.n phosphate (MAP) was as follows. Ten and three-quarters (10.75)kg of a 31% USY slurry was mixed with 18.92kg of silica sol (10.7% of Si02) , 2kg of a 25% (volatile-free weight) gibbsite slurry, 7.5kg of a 16% (volatile-free weight) crystalline boehmite slurry adjusted to pH 2.8 with formic acid, 0.24kg of MAP in 1.9kg H20, and 5.81kg of a 55% (volatile-free weight) clay slurry. The slurry was spray dried and the microspheres exchanged with ammonium sulfate and rare earth nitrate as described above.

A comparison of the performance with a catalyst of the invention is summarized by data in Table 3 and demonstrates the necessity of selecting an appropriate phosphorus source to achieve the desired selectivity and activity. Table 3:5000V/1000Ni §60% Conv.

Sample Activity (c/o=5. Coke H2 Gasoline

Invention 1.45 4.8 0.59 45.7

(Mg Phosphate)

MAP 1.05 5.8 0.75 44.3

Claims

CLAIMS :

1. A cracking catalyst comprising a molecular sieve dispersed in a matrix comprising kaolin clay, synthetic silica-alumina, particulate low surface area macroporous

5 gamma alumina derived from peptizable crystalline boehmite and magnesium phosphate.

2. The catalyst of claim 1 wherein said alumina has a surface area below 125 m²/g.

3. The catalyst of claim 1 wherein the macroporosity 10 of said gamma alumina is centered about 200 Angstrom radius.

4. The catalyst of claim 1 which also contains high surface area gamma alumina.

5. The catalyst of claim l made by a process 5 comprising: combining a molecular sieve zeolite, a silica sol, magnesium phosphate and peptized crystalline boehmite having a surface area below 125 m²/g to form an aqueous mixture and spray drying said mixture.

6. A process for the catalytic cracking of a -0 hydrocarbon feedstock containing nickel and vanadium contaminants which comprising contacting said feedstock with an attrition resistant cracking catalyst under cracking conditions in the substantial absence of added molecular hydrogen in a cracking zone to convert said .5 feedstock into lower molecular weight constituents, wherein said cracking catalyst is the catalyst of claims 1 or 2.