US3165462A

US3165462A - Pretreatment and cracking of heavy mineral oils

Info

Publication number: US3165462A
Application number: US130513A
Authority: US
Inventors: Bernard S Friedman; James P Gallagher
Original assignee: Sinclair Research Inc
Current assignee: Sinclair Research Inc
Priority date: 1961-08-10
Filing date: 1961-08-10
Publication date: 1965-01-12
Anticipated expiration: 1982-01-12

Description

United States Patent 3,165,462. PRETREATMENT AND CRAtIKiblG (9F HEAVY MINERAL 0115 Bernard S. Friedman, Chicago, and James P. Gailagher, Park Forest, 15., assi nors, by mesne assignments, to Sinciair Research, Inc, New York, N.Y., a corporation of Delaware 7 Filed Aug. 10, 1961, Ser. No. 1313513 Ciaims. (Cl. 268-86) This invention concerns the catalytic cracking of heavier mineral hydrocarbon oils to obtain lighter components including gasoline of relatively high octane number. More particularly, the present invention relates to an improved process for the treatment of metal contaminated hydrocarbon oils in which the harmful effects of the metal contaminants on the cracking operation are avoided.

The present invention comprises pretreating a petroleum hydrocarbon feedstock boiling above the gasoline range with acid, subjecting the treated feedstock to catalytic cracking and demetallizing the cracking catalyst. The acid treatment serves to remove some aromatic and hetero components such as nitrogen-, oxygenand sulfurcontaining compounds which are present in most heavy hydrocarbon feeds and interfere with the cracking operation, and also serves to remove some of the metal contaminants from the feedstock.

In this invention an operation involving feed pretreatment and catalytic cracking of heavier mineral hydrocarbon oil feedstocks to produce gasoline is combined with a procedure for reducing poisoning metals on the cracking catalyst to present a much more attractive answer to the problem of catalyst poisoning by heavy metals than either feed treatment or catalyst demetallization alone. Catalyst demetallization alone would not overcome the problem of coke laydown in cracking which is caused by a large asphaltene content in the feed and further would require enormous demetallization facilities to deal with a heavily contaminated feed. Likewise, acid treatment does not ordinarily produce in a simple treatment of a heavily poisoned feedstock, a catalytic cracking feed so low in poisoning metals that their effect on the cracking operation can be ignored.

The catalytic cracking of various heavier mineral hydrocarbons, for instance petroleum or other mineral oil distillates such as straight run and cracked gas oils; shale oils; etc., has been proposed for many years and the catalytic cracking of gas oils is practiced commercially to a considerable extent. As is well known to those familiar with the art, gas oil is a broad, general term that covers a variety of stocks. The term includes any fraction distilled from petroleum or other mineral oil which has an initial boiling point of at least about 400 F., say, up

to about 850 F., and an end boiling point of at least about 600 F., and boiling substantially continuously between the initial boiling point and the end boiling point. Usually the boiling range extends over at least about 100 F. The portion which is not distilled before the end point is reached is considered residual stock. The exact boiling range of a gas oil, therefore, will be determined by the initial distillation temperature (initial boiling point) and by the temperature at which distillation is cut off (end boiling point). In practice, petroleum distillations have been made under vacuum up to temperatures as high as about 1100-1200 F. (corrected to atmospheric pressure). Accordingly, in the broad sense,- a gas oil is a petroleum fraction which boils substantially continuously between two temperatures that establish a range -j falling within from about 400 F. to about 1100-1200 F. Thus, a gas oil could boil over the entire range about 4001200 F. or it could boil over'a narrower range, eg.

about 500-900 F. The gas oils can befurther roughly Patented Jan. 12, 1965 classified by boiling ranges. Thus, gas oil boiling between about 400-500 F. and about 600-650" F. is termed a light gas oil; a medium gas oil distills between about 600-650 F. and about 800-900 F.; a gas oil boiling between about 800-850 F. and about 1100-1200" F. is sometimes designated as a vacuum gas oil. It must be understood, however, that a particular stock may bridge two boiling ranges, or even span several ranges, i.e. include, for example, light and medium gas oils.

A residual stock is in general any petroleum fraction higher boiling than a selected distillate fraction. Any fIaCllOH IEgZIIdESS of its initial boiling point, which includes heavy bottoms, such as tars, asphalts, or other nondistilled material may be termed a residual fraction. Accordingly, a residual stock can be the portion of the crude remaining undistilled at about 1100-1200 F., or it can be made up of a gas oil fraction plus the portion undistilled at about 1100-1200" F. For instance, a Whole. topped crude, is the entire portion of the crude remain-. ing after the light ends (the portion boiling up to about 400 F.) have been removed by distillation. Therefore, such a fraction includes the entire gas oil fraction (400- F to 1100-1200 F.) and the undistilled portion of the crude petroleum boiling above 1100-1200 F.

The behavior of a hydrocarbon feedstock in the cracking reactions depends upon various factors including its boiling point, carbon-forming tendencies, content of catalyst contaminating metals, etc., and these characteristics may affect the operation to an extent which makes a given feedstock uneconomical to employ.

By and large, residual stocks have notbeen catalytically cracked on a commercial scale as their carbon-forming tendencies and catalyst poisoning metals content are generally too great. It has long been recognized that residua and petroleum gas oils which include constituents boiling in excess of about 950 F. normally contain nickel and vanadium and other metallic contaminants which have an adverse effect upon various catalysts employed in petroleum processing operations. In operations such as catalytic cracking and the like, the presence of very small concentrations of these contaminants in the feed stream leads to the rapid poisoning of the catalyst, causing a significant decrease in the product yield, an increase in coke and gas production and a marked shortening in the life of the catalyst. Also, some residual stocks are so heavily metals-contaminated that their use even as a fuel is limited,

0 since such contaminants attack the refractories used to high accumulation of poisoning metals in the cracking system, this type of operation represents a substantial cost factor. Improvement in the feedstock characteristics become even more important as the cost of the catalyst rises and thus the effects of low feedstock quality are particularly burdensome in systems employing cracking catalysts containing relatively expensive synthetic com ponents.

Although there have been numerous methods proposed in the past for removing contaminants from high boiling petroleum fractions, it has been found that when a severely contaminated feed is used, such methods are not fully effective, generally'result in loss of substantial quantities of the oil, and in many cases are prohibitively expensive.

As a result, it has generally been necessary to restrict the feed streams to catalytic petroleum processing units to those fractions which boil below. the range in which the contaminants are found and to avoid asmuch as possible from 15 to about 150-200 p.s.i.g. the percent of precipitate is greatly increased. The concentration of the precipitating a ent may be regulated by pressure for particular crude oils which vary in asphaltic content or in content of metals and which vary somewhat in solubility for hydrogen chloride. The effectiveness of the treatment is increased by mild agitation which assists in saturating the crude oil with the precipitating agent and agglomerating sludge particles. 1

Some residual stocks, such as vacuum topped crudes, have been found too viscous for easy intimate contact and effective saturation of the residual with the precipitating agent. Also, the viscosity tends to prevent the precipitates from quick complete settling out from the treated oil. Therefore materials which act as diluents and/or solvent extracting agents frequently must be added to the feedstock. Such materials are generally of the type useful in extracting lubricating oils, gas oils and the like. The diluent or solvent may be chosen from a number of hydrocarbon types, as well as other extracting solvents or counter solvents well-known in the art, such as S Whole crude oil or straight-run naphthas may be used, but especially suitable solvents are the liquified hydro carbons of about 3 to 7 carbon atoms, preferably of about 3 to carbon atoms. The solvent is normally employed in a solvent-to-oil ratio of from about 0.5/1 to 20/1 and preferably the solvent-to-oil ratio is about 1/1 to 10/1. At least about 75 weight percent, usually about 80 to 95 weight percent of the feed to the treating zone is recovered.

When the presence of the diluent is necessary for proper contact between acid and hydrocarbon feedstock the diluent is added to the feed before or simultaneously with the acid. Alternatively, the solvent may be used merely to complete precipitate removal. In such practice, the acid is contacted and mixed with the charging stock to saturate the residual oil and then the charging stock is extracted with the selective solvent to form a raffinate phase containing the precipitate and an extract phase which contains the treated oil, free of precipitating components. The sludge or precipitate, of course, contains a substantial portion of the metal content, coke precursors and some other undesirable materials originally present.

The method of contacting the residual feed, that is, whether the selective solvent will be added along with the acid or subsequent to the acid contact, will depend to some extent upon the acid that is used. For instance, when a residual oil is subjected to treatment with a hydrogen halide gas, such as hydrogen chloride, slightly elevated pressures and temperatures sufficient to reduce the viscosity of the oil are generally used. While no sludge is collected during addition of this acid, contact of the treated oil with a solvent will precipitate the in soluble material containing a substantial portion of the metal poisons and coke precursors originally present. When a liquid acid such as xylene sulfonic acid is used as the contacting agent, the solvent is preferably added along with the acid to reduce the viscosity of the feed as well as to permit separation of the sludge formed. However, either sequence of contacting steps can generally be adapted for either type of treating agent.

The precipitate-free oil may be washed with an aqueous medium such as water or an alkaline solution or blown with an inert gas to free the oil or residual amounts of acid which may have remained in the treated '00. The acid component dissolves in the aqueous phase and is separated from the treated oil. The oil that is separated from the precipitated metal contaminants is conducted to a fractionation tower where distillation temperatures are maintained. An overhead fraction boiling below about 400 F. is removed from the tower. Distillation also will remove any hydrocarbon or other volatile solvent used in the acid pretreatment, as well as any traces of hydrogen halide not removed by the water wash. Each of these components is usually recycled back to the treating zone, with an intermediate purification procedure if necessary. The 400 F.+bottoms from the fractionation is fed to the catalytic cracker. This bottoms frac tion contains the entire gas oil fraction and the undistilled portion of the crude petroleum boiling above about ll001200 F.

The acid sludge is withdrawn from the precipitate-free oil layer and may be treated with water or a caustic scrubhing to remove the residual acid from the sludge. 'The acid may then be recycled, with or without purification back to the treating zone where the fresh hydrocarbon oil is contacted with the acid. Another aspect of this invention is presented when the demetallization procedure, to be described hereinafter, utilizes a chlorination process for catalyst demetallization. T he chlorinator efiluent from the demetallization unit consists primarily of hydrogen chloride, chlorine, inert gases and metal chlorides. The metal chlorides may be condensed from the vapors as by indirect cooling with water and the remaining hydrogenchloride-containing gas stream collected for hydrogen chloride pretreatment of the charging stock. This gas may be combined with the hydrogen chloride that has been removed from the treated oil and/or the sludge by water washing and/ or by distillation.

Pretreatment of the charging stock with the acidic material gives a partial reduction in metals content of the treated oil. In this invention pretreatment may remove only about 10% of the poisoning metal in the feedstock, but preferably much more of the poison. Thus the treated oil or the portion used in cracking contains perhaps about 4090 or more Weight percent less of one or both of nickel and vanadium than the hydrocarbon charged to the pretreatment reaction; preferably, there is this much reduction in nickel and vanadium or in each of these metals. Frequently the reduction of one or all of the nickel, and vanadium will be about 50-90 weight percent. But pretreatment of the feedstock usually does not remove metal contaminants to a point that is insignificant in subsequent catalytic cracking. The amount of metal to be removed from the feed is, in turn, determined by a number of factors: the amount of poison remaining in the pretreated oil, the proportion of pretreated oil sent to the catalytic cracking, the amount of other hydrocarbon material with which the pretreated oil is blended to prepare the cracker feed, and the poisoning metal content of this additional feedstock. The metals remaining in the pretreated oils accumulate on the catalyst during the cracking operation and unless steps are taken to prevent excess accumulation, excessive dehydrogenation takes place in catalytic cracking, severely reducing the yield of gasoline in the cracker efiluent. The pretreated oil, before any other material is blended has a least about 1.0 ppm. nickel and/ or 2 ppm. vanadium and has a preferred maximum metal content of about 25 ppm. nickel and/or 50 ppm. vanadium.

The portion of the pretreated oil boiling above 400 F. may be combined with other cracking feed in any proportion, but the cracker feed preferably contains at least about 10% of the treated oil, preferably about 20 to 70%. The remaining portion of the cracker feed may comprise cracking feeds of more or less conventional types, that is, virgin gas oil fractions or recycle gas oils from this cracker or other catalytic crackers, etc. Alternatively, the entire effluent can be sent to the cracker without diluting with extraneous feed material. Pretreatment conditions and the proportion of the treated oil boiling above about 400 P. included in the cracker feed will be adjusted to provide a feed containing more than about 1.0 ppm. nickel and/or 1.0 ppm. vanadium in order to justify the provisions made in this invention for cracking catalyst demetallization and preferably the total feed to cracking will contain more than about 1 ppm. nickel and/ or 2 ppm. vanadium but often less than about 10 ppm. nickel and/or 25 ppm. vanadium. At least about 1 ppm. nickel and/ or about 1 or 2 ppm. vanadium is contributed to the cracked feed by the treated oil boiling about 400 F. The use tion unit withthe catalytic cracker counteracts this remaining metal content,' thereby enabling processing of a much deeper cutiof the crude stock. 1 i

Catalytic'cracking is ordinarily effected to produce gasoline as the most valuable product. The feed to the cracking zone is substantially vaporized and catalytically treated under more orless conventional fluid catalytic cracking conditions. Cracking is generally conducted at temperatures of about 750 to 1000 F., preferably about 850to 975 F, and a pressure between atmospheric and about of a catalystdemetallizaij coke from the catalyst" is "economy only' enough air is used to supply the needed oxygen; Average residence time for a portion of catalyst in the regenerator may be. of the order of about six minutes and the. oxygen content. of the .efiluent gases from the regenerator is desirably less than about /2%; The regeneration of any particular quantumv of catalyst is gen- 100 p.s.i.g., preferably about atmospheric to' 5-25 p.s.i.g., L

at, a weight hourly space velocity from about 0.1 to to obtain about a 40-80 volume percent, preferably about i 50 to 65%, conversion of the catalytic feedstock to gasoline and other desired lighter components.

The products'of the cracking-are conducted to afractionation column where the lower boiling gasoline constituents'of the cracker effluent having an approximate 375 430 F. end point are vaporized and removed from the system and may be used as gasoline blending components or other products. Also, products, as gases, boiling erally regulated to give a carbon content of less than about 5.0%, generally less than about 0.5%. Regeneration puts; the catalyst in a substantially carbon-free state, that is, the

state Where'little','if any, carbon is burned or oxygen consumed even when the catalyst is contacted with oxygen at temperatures conducive to combustion.

In the treatment to take poisoning metals from the cracking catalyst the amount of metal is removed which is necessary to keep the average metal content of the catalyst in the cracking system below the limit of'the units tolerbelow the gasoline range are removed from the system. 7

The gas oil cycle. stock, usually boiling between about 7 400 F. and about 850-950 F. may be sent back to the treating zone or catalytic cracking zone by blending it with the petroleum feedstock and/ or the poisoned bottoms fraction.

weight condensed ring aromatic hydrocarbons. This cycle oil may therefore advantageously be brought back to the V treating zone and contacted along with the charge stock with the treating acid. The treatment results in substantial reduction of'metal contaminants and coke precursors from the charge stock and substantial'reductionin the refractory aromatic hydrocarbons present in the cycle oil. The material boiling above about 950 F. may be removed from the system and used as a residual fuel component. In the cracking operation a batch, semi-continuous or continuous system may be used but most often is a continuous fluidized system. i i

The cracking catalyst is of the solid refractory metal oxide type known in the art, for instance silica, alumina, magnesia, titania, etc, or their mixtures. portance are the syntheticgel-containing catalysts, such Of most imas the synthetic and the semi-synthetic, i.e. synthetic gelsupported on a carrier such as natural clay, cracking catalysts; The cracking catalysts which have received the widest acceptance today are usually predominantly silica, that is silica-based, and may contain solid acidic oxide promoters, e.g. alumina, magnesia, etc., with the promoters usually being less than about of the catalyst, preferably about 5 to 25%. These compositions are calcined to a state of very slight hydration. The crack ing catalyst can be of macrosize, for instance, bead form or finely divided form, and employedasia fixed 'rnoving' or fluidized bed. In a highly preferred form" of this invention finely divided (fluidized) catalyst, for instance having particles predominantly in the 20 to 150 micron range, is disposed as a fluidized bed in thereaction zone to which the feed is charged continuously A portion'of the catalyst is continuously ,withdrawn and passed to a regeneration zone Where coke or carbon is with a free oxygen-containing gas before its return to the reaction zone. In cracking, coke yield maybe held'to a minimum through the use of good steam stripping and a high steam partial pressure. Regeneration of a catalyst to remove 'carbonis a relatively quick procedure in most commercial catalytic conversion operations. For example,

" in a typical fluidizedcracking unit, a portion of catalyst is continually being removed'from the reactor and sent to the regenerator for contact with air at about 950 to 1 2001 F.,' more usually about 1000 to 1150 F. Combustion of These cycle oil fractions are substantially free I of metal'poisons. The cycle oil and in particular the por-I tion boiling above about 750 F.'is rich in high molecular ance for poison. The toleranceofthe cracker for poison in turn determines to a large extent the amount of metals removed in the catalyst dernetallization procedure. Where the catalyst contains a greater amount of poisoning metal, a particular treatment will remove a greater amount of metal; for example, if the cracker can tolerate an average of 100 ppm. Ni and the demetallization process can remove 50% of the nickel content ofthe catalyst, only .50 ppm/of nickel can be removed in a pass through the catalyst demetallization system; However, where the cracker can-tolerate 500 ppm. of nickel, it is possible to remove 250 .p.p.m. nickel from the catalyst with each pass through the demetallization system. it is advisable,

Qtherefore, to operate the cracking and demetallization procedures with a catalyst having a metals content near the limit of tolerance of the cracker for poisoning metals.

In the treatment to take poisoning metals from the cracking catalyst a large or small amount of metal can be removed as desired. 7 The .demetallization treatment generally removes about 10m 90% of oneor more poisoning metals from a catalyst portion which passes through the treatment. Advantageously a demetallization system is used' which removesabout 60 to 90% nickel and 20-40% vanadium from the treated portion of catalyst. Preferably at least of the equilibrium nickel content and 15% of the equilibrium-vanadium content is removed. 'The actual'time or extent of treating depends on various factors, and is controlled by the operator 7 according .to the situation he faces, e.g. the extent of metals content in the feed, the level of conversion unit tolerance for poison, the sensitivityof'the particular cata lyst toward aparticular phase of" the demetallization procedure, etc. Also, the thoroughness of treatment of any quanturn'of catalyst incommerc'zial practice is balanced against the demetallization rate chosen; that is, the amount V of catalyst, as'compared to the total catalyst in the convertion treatment per unit of time.

burned from the catalyst in a fluidized bed by contact sion system proper, which is'subje'cted to the demetalliza- A high rate of catalyst withdrawal from the conversion system and quick passage through a mild demetallization procedure may suffice as readily as a more intensive demetallization at a slower rate to keep the total of poisoning metal in the conversion reactor within the tolerance of the unit for poison. In a continuous operation of the commercial type a satisfactory treatingflrate maybe about 5 to 50% of the total catalyst inventory in the system, per twenty-four hour day of operation although'other treating rates maybe used. With a continuously circulating catalyst stream, such as in the ordinary ffluid system a slip-stream of catalyst,"

at the equilibrium level of poisoning metals may be pid. and for reasons of 59 removed intermittently or continuously from the regenerator standpipe of the cracking system. The catalyst is subjected to one or more of the demetallization procedures described hereinafter and then the catalyst, substantially reduced in contaminating metal content, is returned to the cracking system.

The dernetallization of the catalyst will generally include one or more processing steps. Copending patent applications Serial Nos. 758,681, filed September 3, 1958; 763,833 and 763,834, filed September 29, 1958; 767,794, filed October 17, 1958; 842,618, filed September 28, 1959; 849,199, filed October 28, 1959; 19,313, filed April 1, 1960; 38,810, filed June 30, 1960; 47,598, filed August 4, 1960; 53,380, filed September 1, 1960; 53,623, filed September 2, 1960; 54,368, 54,405 and 54,532, filed September 7, 1960; 55,129, 55,160 and 55,184, filed September 12, 1960; 55,703, filed September 13, 1960; 55,838, filed September 14, 1960; 67,518, filed November 7, 1960; 73,199, filed December 2, 1960; and 81,256 and 81,257, filed January 9, 1961; all of which are hereby incorporated by reference, describe procedures by which vanadium and other poisoning metals included in a solid oxide hydrocarbon conversion catalyst are removed by dissolving them from the catalyst or subjecting the catalyst, outside the hydrocarbon conversion system, to elevated temperature conditions which put the metal contaminants into the chloride, sulfate or other volatile, water-dispersible or more available form. A significant advantage of these processes lies in the fact that the overall metals removal operation, even if repeated, does not unduly deleteriously affect the activity, selectivity, pore structure and other desirable characteristics of the catalyst.

Treatment of the regenerated catalyst with molecular oxygen-containing gas is employed to improve the re moval of vanadium from the poisoned catalyst. This treatment is described in copending application Serial No. 19,313, filed April 1, 1960, and is preferably performed at a temperature at least about 50 F. higher than the regeneration temperature, that is, the average temperature at which the major portion of carbon is removed from the catalyst. The temperature of treatment with molecular oxygen-containing gas will generally be in the range of about 1000 to 1800" F. but below a temperature where the catalyst undergoes any substantial deleterious change in its physical or chemical characteristics, preferably a temperature of about 1150 to 135 F. or even as high as 1600 F. The duration of the oxygen treatment and the amount of vanadium prepared by the treatment for subsequent removal is dependent upon the temperature and the characteristics of the equipment used. If any significant amount of carbon is present in the catalyst at the start of this high-temperature treatment, the essential oxygen contact is that continued after carbon removal, which may vary from the short time necessary to produce an observable effect in the later treatment, say, a quarter of an hour to a time just long enough not to damage the catalyst. In any event, after carbon removal, the oxygen treatment of the essentially carbon-free catalyst is at least long enough to provide, by conversion or otherwise, a substantial amount of vanadium in its highest valence state at the catalyst surface, as evidenced by a significant increase, say at least about preferably at least about 100%, in the vandium removal in subsequent stages of the process. This increase is over and above that which would have been obtained by the other metals removal steps without the oxygen treatment. The maximum practical time of treatment will vary from about 4 to 24 hours, depending on the type of equipment used. The oxygen-containing gas used in the treatment contains molecular oxygen as the essential active ingredient and t ere is little significant consumption of oxygen in the treatment. The gas may be oxygen, or a mixture of oxygen with inert gas, such as air or oxygen-enriched air, containing at least about 1%, preferably at least about 1.0% 0 The partial pressure of oxygen in the treating 10 gas may range widely, for example, from about 0.1 to 30 atmospheres, but usually the total gas pressure will not exceed about 25 atmospheres.

The catalyst maypass directly from the oxygen treatment to a vanadium removal treatment especially where tms is the only important contaminant, as may be the case when a feed is derived, for example, from Venezuelan crude. Such treatment may be a basic aqueous wash such as described in copending patent applications Serial No. 767,794, and Serial No. 39,810. Alternatively vanadium may be removed by a chlorination procedure as described in copending application Serial No. 849,199. Vanadium may be removed from the catalyst after the high temperature treatment with molecular oxygen-containing gas by washing it with a basic aqueous solution. The pH is frequently greater than about 7.5 and preferably the solution contains ammonium ions which may be in the form of NH,} ions or organic-substituted NH4+ ions such as methyl ammonium and quatenary hydrocarbon radical ammoniums. The amountof ammonium ion in the solution is sufiicient to give the desired vanadium removal and will often be in the range of about 1 to 25 or more pounds per ton of catalyst treated. The temperature of the wash solution may vary within wide limits: room temperature or below, or higher. Temperatures above 215 F. require pressurized equipment, the cost of which does not appear to be justified. Very short contact times, for example, about a minute, are satisfactory, while the time of washing may last 2 to 5 hours or longer. After the ammonium wash the catalyst slurry can be filtered to give a cake which may be reslurried with water or rinsed in other ways, such as, for example, by a water wash on the filter, and the rinsing may be repeated, if desired, several times.

Alternatively, after the high temperature treatment with oxygencontaining gas, treatment of a metals contaminated catalyst with a chlorinatnig agent at a moderately elevated temperature up to about 1000 F. is of value in removing vanadium and iron contaminants from the catalyst as volatile chlorides. This treatment is described in copending application Serial No. 849,199; 54,405; 54,532; 55,703; and 67,518. The chlorination takes place at a temperature of at least about 300 F. up to about 1000 F, preferably about 550 to 650 F. with optimum results usually being obtained near 600 F. The chlorinating agent is essentially anhydrous, that is, if changed to the liquid state no separate aqueous phase would be observed in the reagent.

The chlorinating reagent is a Vapor which contains chlorine or sometimes HCl, preferably in combination with carbon or sulfur. Such reagents include molecular chlorine but preferably are mixtures of chlorine with, for example, a chlorine substituted light hydrocarbon, such as carbon tetrachloride, which may be used as such or formed in-situ by the use of, for example, a vaporous mixture of chlorine gas with low molecular weight hydrocarbons such as methane, n-pentane, etc. About 1-40 percent active chlorinating agent based on the weight of the catalyst is generally used. The carbon or sulfur compound promoter is generally used in the amount of about 1-5 or 10 percent or more, preferably about 2-3 percent, based on the weight of the catalyst for good metals removal; however, even it less than this amount is used, a considerable improvement in metals removal is obtained over that which is possible at the same temperature using chlorine alone. The chlorine and promoter may be supplied individually or as a mixture to a poisoned catalyst. Such a mixture may contain about 0.1 to 50 parts chlorine per part of promoter, preferably about 110 parts per part of promoter. A chlorinating gas comprising about 1-30 weight percent chlorine, based on the catalyst, together with one percent or more S Cl gives good results. Preferably, such a gas provides 11() percent C1 and about 1.5 percent S Cl based on the catalyst. A saturated mixture of CC], and C1 or removal, this wash preferably takes place before the ammonium wash.

Alternative to the removal of poisoning metals by procedures involving contact of the sulfided or sulfated catalyst with aqueous media, nickel poison and some iron may be removed through conversion of the nickel sulfide to the volatile nickel carbonyl by treatment with carbon monoxide, as described in copending application Serial No. 47,598. In such a procedure the catalyst is treated with hydrogen at an elevated temperature during which nickel contaminant is reduced to the elemental state, then treated, preferably under elevated pressure and at a lower temperature with carbon monoxide, during which nickel carbonyl is formed and flushed oil the catalyst surface. Hydrogenation takes place at a temperature of about 800 to 1600" F., at a pressure from atmospheric or less up to about 1000 p.s.i.g. with a vapor containing to 100% hydrogen. Preferred conditions are a pressure up to about p.s.i.g. and a temperature of about 1100 to 1300 F. and a hydrogen content greater than about 80 mole percent. The hydrogenation is continued until surface accumulations of poisoning metals, particularly nickel, are substantially reduced to the elemental state. Carbonylation takes place at a temperature substantially lower than the hydrogenation, from about ambient temperature to 300 F. maximum and at a pressure up to about 2000 p.s.i.g., with a gas containing about 50-100 mole percent CO. Preferred conditions include greater than about 90 mol percent CO, a pressure of up to about 800 p.s.i.g. and a temperature of about l00l80 F. The CO treatment serves generally both to convert the elemental metals, especially nickel and iron to volatile carbonyls and to remove the carbonyl.

After the ammonium wash, or after the final treatment which may be used in the catalyst demetallization procedure, the catalyst is conducted back to the cracking system. Where a small amount of the catalyst inventory is demetallized, the catalyst may be returned to the cracking system, preferably to the regenerator standpipe, as a slurry in its final aqueous treating medium. Where a large amount of catalyst inventory is treated, lest the water put out the fire or unduly lower the temperature in the regenerator, it may be desirable first to dry a wet catalyst filter cake or filter cake slurry at say about 250 to 450 F. and also, prior to reusing the catalyst in the cracking operation it can be calcined, say at temperatures usually in the range of about 700 to 1300 F. Prolonged calcination of the catalyst at above about 1100 F. may sometimes be disadvantageous. Calcination removes free water, if any is present, and perhaps some but not all of the combined water, and leaves the catalyst in an active state without undue sintering of its surface. Inert gases such as nitrogen frequently may be employed after contact with reactive vapors to remove any of these vapors entrained in the catalyst or to purge the catalyst of reaction products.

The demetallization procedure employed in this invention has been found to be highly successful when used in conjunction with systems employing fluidized cracking catalyst to control the amount of metal poisons on the catalyst. When such catalysts are processed, a fluidized solids technique is recommended for these vapor contact demetallization procedures as a way to shorten the time requirements. Any given step in the demetallization treatment is usually continued for a time sufiicient to effect a substantial conversion or removal of poisoning metal and ultimately results in a substantial increase in metals removal compared with that which would have been removed if the particular step had not been performed. After the available catalytically active poisoning metal has been removed, in any removal procedure, further reaction time may have relatively little effect on the catalytic activity of the depoisoned catalyst, although further metals content may be removed by repeated or other treatments.

This invention will be better understood by reference to the accompanying drawing which shows the schematic of a representative processing system but is not to be construed as limiting.

A feed contaminated with poisoning metals, for example crude oil, vacuum gas oil or a vacuum asphalt, is fed by line 10 to treating zone 12. Acid is brought into zone 12 by line 14. When a solvent is to be used it may be introduced into the treating zone by line 16. The treating zone may comprise one or more towers or other vessels adapted to permit the saturation of the oil with the acid. Suitable coils, jacketing or other temperature control means are provided, as are means for agitation. Zone 12 is usually equipped with acid gas vent line 18 which runs into acid gas recycle line 20 and associated compressor 22 for recycling to zone 12. Reaction conditions within zone 12 are temperatures ranging from about 50 to 500 F. and pressures in the range of 25 to 600 p.s.i.g. The residence time of the oil may range from 5 minutes to 2 hours. An upper layer of treated oil containing a deashed oil-solvent mixture, along with the acidic coagulating component is passed by line 24 to a water washing vessel 25, while a lower layer constituting acid sludge may be withdrawn from the bottom of zone 12 through line 23 for disposal as desired. In the practice of this invention acid sludge may be treated by means of a Water or caustic scrubbing in tank 30 to recover entrained acid component which after removal of water can be recycled back to treating zone 12, by lines 32 and 14.

The treated oil is contacted in zone 26 with water which is introduced by means of line 34 preferably as steam. Temperature and pressure conditions in zone 2-6 are adjusted to secure the desired removal of acid component from the oil. Washing zone 26 may comprise any suitable number and arrangement of stages. The Water-acid layer is separated and removed by means of line 36. The acid component may be removed from the water and recycled back to zone 12 by means not shown. The treated and washed oil is removed from zone 26 by means of line 38 and brought to fractionation tower 40. The fractionator separates any acid component that has not previously been removed in the Washing zone 26, and the acid may be conducted by

lines

41, 20 and 14 back to the treating zone. Line 42 removes gases having about 1 to 4 carbon atoms and line 44 removes gasoline components and any naphtha or distillate fraction of similar boiling point. The bottoms fraction boiling above about 400 F. is removed by line 48 and brought to the cracking unit 46 by line 52. The bottoms fraction may be blended with other cracking feed components from an external source 50 along with any additional cracking feed components to make up the final cracking feed.

The cracker feedstock and fluid cracking catalyst are brought to the cracker 46 by the line 52. The cracker may be provided with the cyclone separator 54 to disentrain catalyst fines from the cracker effluent which leaves by line 56. This effluent is brought to fractionator 58 where components of the cracker efiiuent are withdrawn by line 60 for gases, line 62 for gasoline, line 64 for distillate components comprising light cycle oils and line 66 for materials higher boiling than the distillate oil. Fractionator 58 may be a plurality of stages but in the practice of this invention a single stage fractionator usually sutfices. The heavy components may be withdrawn from the system by line 68, or alternatively they may be recycled by

lines

70, 72, and 10 to the treating zone along with distillate components from the cracker effluent from line 6 but preferably the cycle oil fraction in the cracker effluent is recycled to the catalytic cracker by

lines

66, 70, 72, 76 and 52, since it is substantially poisonfree.

Contaminated catalyst is continuously remo'ed from the cracker 46 by the standpipe 77 whence it is conducted, for example, by air from the source 78 to the regenerator 80 by the pipe 32. The regenerator is provided with the regenerator standpipe 86 for demctallization. The

drawing illustrates a demetallization system which includes apparatus for sulfiding, chlorinating, washing and filtering the catalyst.

Pipes

88 and 90 conduct the catalyst to an outer chamber 92 of the sulfider 04 where V the catalyst may be preheated before entering the main chamber through opening 96. In the sulfider the cat.- alyst passes countercurrently as a fluidized bed to sulfiding vapors entering by line 98. 'aCtalyst exits by line 100 and waste sufiding gas exits by line 102. Line -0 I brings the catalyst to chlorinator 104 where "it passes countercurrent to chlorinating vapor entering from line 106. -Exhaust chlorinating vapor and vaporized metal compounds leaveby line 108 and catalyst, reduced in vanadium content passes by line 110' to slurry tank 112 which is kept supplied with water, perhaps containing pH-adjusting components, from the line 114. Agitation ismaiutained in the slurry tank by suitable means (not shown) and the slurry is quickly withdrawn byline 116 to the filter 118. Although shown as a rotary drum filter, it may be of any desired type. The filter produces a catalyst cake which may bewashed by water from a source not shown and scraped from the filter by doctor blade 122. Excess aqueous material is removedirorn the system by line 124. Catalyst goes by route 126 to wash tank 128. A slurry of catalyst in wash water may be brought by line 130 back to regenerator S0. The chlori nator effluent removed by line 108 is conveyed to baffle tower 132 where the metal chlorides may be condensed from; the vapors by cooling with air or by indirect conthe system by line 135. The gases are removed by line 136 and conveyed to knock-out drum 140 wherehydrogen chloride is removed byline. 142 and returned tothe treating zone 12, via

lines

142, 20 and 14. The following examples of the process of this invention are'not to be considered limiting.

' Examp lgz I F. and 50%boils below 665 F, contained 0.97% sulfur, 0.18% nitrogen, 25 ppm. nickel, measured as Ni-O and 51 ppm. V measured as V 05. j This crude oil is contacted in a rocking autoclave for about minutes "at'a temperature of about 70 and a pressure of 50 p.s.i;g., with about 3.3 weight percenttof anhydrous HCl. The.

an ILG tion of the silica-alumina catalyst is continuously removed from the cracking reactor and brought to a regenerator. Average residence time in the regenerator is about 5 minutes at a temperature of about 1100 F. before catalystis returned to the cracking reactor at a carbon level of about 0.4%.

About 0.2 pound of virgin catalyst is added to the cracking reactor for each barrel of feed processed to make up for catalyst which is inadvertently lost from the sys- 'tem or which, due to physical" deterioration, is discarded from the system. About 25% of the cracking catalyst inventory, poisoned to a metals level or about 450 ppm.

, nickel, and 3200 ppm. vanadium, is sent each day as a side stream from the regenerator to demetallization. In the demetallization process the catalyst is held in air for about an hour at'about 1300 F. and then sent to a sulfiding zone where it is fluidized with H 8 gas at a temperature of about 1175 F. for about an hour. The'catalyst is then purged with flue gas at a temperature of about 575 F. and chlorinated in a chlorination zone with an equirnolar mixture of cl and CCL; at about 600 F.

After about 1 hour no trace of vanadium chloride can be found in the chlorination efiluent and the catalyst is quicklywashed with water. A pH of about 2 is imparted to this wash medium by chlorine entrained in the catalyst and the wash serves to remove nickel chloride. The demetallization procedure removes about 60% of the nickel and about 25 of the vanadium on the catalyst. The

i treating zone." 7 j tact with-water introduced by line 134 and removed front acid sludge produced is allowed to settle and the oil is decanted off. The oil was obtained in a yield of abou't' 89' weight percent of the crude to the autocl'ave and .analyzes 7.4 ppm. nickel oxide and 21.5 ppm vanadium, Thetreated oil is fractionated and the hydrogen The 400 F.+bottorns fraction amounting to about 66 percentof the treated oil and containingaboutlll ppm.

7 nickel and 32.6 ppm; vanadium is blended with a portion ofcycle oil from the cracker for a metals content of about 7 ppm. nickel and catalytiocra cking teed. a

In. thecatalytic cracker the feedstock contacts a syn- 20 p m; vanadiu m in the .thetic gel silica-alumina catalyst, having an A1 0 content of about 25% at a temperature of about'900 to 925 F. and a pressure of aboutS p.s.i.g. The cracked products are introduced to a fractionator where approxi-' mately gasolineand other low boilingcomponents are removed. The residue, including gas-oil fractions,

is r ycled to the cracker for further processing. por- Q 2470 ppm. V 0 isnea'ch day sentas a side stream from s V chlorination efiluent is conducted to a zone where the metal chlorides are removed and the gases are separated so that hydrogen chloride may be recycled back to the 7 Example 11 p A The bottoms from an atmospheric crude oil distillation had an API gravity of 18.7, a kinematic viscosity at 122 F. or 242.7 and at 210 F. of 27.76 and a pour'point of F. This light reduced'cr'ude had an initialboiling point of 486. F. and contained 10% of materials boiling below 710 F., and 50% boiling below 951 F. (converted to atmospheric pressure). 0.37% nitrogen, 1 .4% su'lfur, 0.61%' oxygen, 4.898% pentaneinsolubles, 49 ppm. Ni() and p.p.rn. V 0 This still bottoms was contacted with n-pentane in a solvent/oilratio 0113 to land about 6'weight percent of .xylene sulfonic acid, based on the weight of the tower bottoms, and was mixed and agitated for about /2 hour at atmospheric pressure and a temperature of about 75 F. After treatment the sludgeis allowed to settle and the treated oil is decanted oifand then the acid is removed by means of a water-wash. The treatedoil, substantially 'free of the acid, amounts to a yield of 83 weight percent based 'on the tower bottoms to the treating zone.

oil contains 12 ppm; nickel, 32 ppm; vanadium, a carbon residue of 3.88% and a sulfur content of 0.9 weight" v percent, The treated oil is blended with a portion of cycle .oil'from the cracker for a metals content of about 7.5 ppm. nickel and 20 ppm. vanadium in the catalytic cracking feed. In the catalytic cracxed the feed contacts a synthetic gel silica-alurnina catalyst having an A content of about 25% at a temperature of about 95.0 to 975F. and'a pressure' of about 5 p.s.i.g. The cracked products are introduced to'a iractionator where a 55% yield of gasoline and other components is removed, T be 'cycle gas oil is recycled to thecracker for further processing, "A portion of the silica-alumina catalyst is continu- 'ously removed froin the cracking reactor and brought to, c

a r'egenerator. Average residence time in the regenerator is about 5 minutes at a temperature of about 1100 F. be-

fore returning to the, reactor, at a carbon level ofless than 1 about 0.5%. in I a a 7 About 30% perday of the cracking catalyst inventory, poisoned to'a metals levelof about 405 ppm. NiO and 3 V the regenerator to demetal-lization. In the demetallization process the catalyst is; held "in air for about an'hour at It contained about a The about 1300 F. and then sent to a sulfiding zone where it is fluidized with'H s gas at a temperature of about 1175 F. for about 1 hour. Dilute nitric acid is brought in contact with the sulfided catalyst and the slurry is aerated for about 10 minutes at a temperature of 200 F. to convert nickel poisons to dispersible form and remove them. The catalyst is then washed with an ammonium hydroxide solution having a pH of about 8 to 11, removing the available vanadium. The catalyst, substantially reduced in nickel and vanadium content is filtered from the wash slurry, dried at about 350 F. and returned to the regenerator. Thetreated catalyst analyzes a metals content of 160 p.p.m. nickeland 1855 p.p.m. vanadium.

Example I III A third run was conducted with a Sour West Texas asphalt having an initial boiling point of about 1050 F., a specific gravity of 8.9 API, 21 Conradson carbon content of about 19.6% and a metals level of 30 p.p.m. nickel oxide and 58 p.p.m. of vanadium pentoxide. The asphalt contained 11.99% pentane insolubles and had a Furol viscosity at 250 F. of 158.5. It was treated for 2 hours at a temperature of about 250275 F. and a pressure of about 250-500 p.s.i.g. with about 15 weight percent of anhydrous HCl in a rocking autoclave. The mixture was extracted with n-pentane in a solvent-to-oil ratio of 4 and the ratlinate phase containing the sludge was drawn oif from the bottom of the autoclave. The extract phase containing the treated oil and solvent is distilled to remove the n-pentane and HCl. The extracted oil, amounting to about 77 weight percent yield based on the asphalt and analyzing 7.6 p.p.m. nickel oxide, 21.6 p.p.m. vanadium pentoxide and having a Conradson carbon content of about 7%, is diluted with a portion of cycle oil from the cracker for a metals content of about 4.8 p.p.m. nickel oxide and 13.5 p.p.m. vanadium pentoxide in the catalytic cracking feed. The feed is catalytically cracked at a temperature of about 950 F., at 10 p.s.i.g. pressure in the presence of a synthetic silica-alumina catalyst containing about 13% A1 0 The cracked products are introduced to a fractionator where a 60% yield of gasoline and other low boiling components are removed. The gas oil fraction is recycled to the catalytic cracker and the residue, products boiling above about 950 F., is recycled to the acid treating zone for further processing. A portion of the silica-alumina catalyst is continuously removed from the cracking reactor and brought to a regenerator. Average residence time in the regenerator is about minutes at a temperature of about 1100 F., before returning to the reactor at a carbon level of about 0.5%.

About 20% of the cracking catalyst inventory poisoned to a metals level of about 380 p.p.m. nickel and 2410 p.p.m. vanadium, is each day sent as a side stream from the regenerator to demetallization. In the demetallization process the catalyst is held in air for about an hour at about 1300 F in H S for about an hour at about 11 5 0 F., in mixed C1 and CCL; for an hour at about 600 F. and washed with water. The catalyst is filtered from the wash slurry, dried at about 350 F. and returned to the regenerator. The treated catalyst is analyzed and shows a metals content of 150 p.p.m. nickel and 1810 p.p.m. vanadium.

Thus, this invention provides for overcoming poisoning efiects by a balanced process which includes acid pretreatment of the cracking feed and cracking catalyst demetallization.

It is claimed:

1. A method for preparing gasoline which comprises contacting a hydrocarbon cracking feedstock boiling above the gasoline range and containing at least about 1 p.p.m. nickel and at least about 1 p.p.m. vanadium by including in said feedstock the residual product obtained as hereafter set forth, with a solid cracking catalyst under cracking conditions to produce gasoline, removing from the cracking system catalyst contaminated with metal contarninant, the removed catalyst contaim'ng at leastlabout 50 p.p.m. nickel and at least about 50 p.p.m. vanadium, demetallizingthe catalyst to remove at least 50% of the nickel and at least 15% of the vanadium from the catalyst, returning the catalyst to said cracking system and recovering gasoline product from said cracking; said feedstock containing the residual product obtained by treating a mineral oil hydrocarbon boiling above about 650 F. and containing at least about 5 p.p.m. nickel and at least about 5 p.p.nnvanadium with a metaland -asphalt precipitating acid to reduce by about 10 to the content of said contaminant, said residual product containing at least about 1 to about 25 p.p.m. nickel and at least about 2 to about 50 p.p.m. vanadium and less metal contaminant than said mineral oil hydrocarbon. q

2. The process of claim 1 in which catalyst demetallization includes contact of the catalyst with a vapor reactive withametal contaminant.

3. The process of claim 1 wherein the acid treatment is carried out by contacting the mineral hydrocarbon oil with an acid selected from the group consisting of hydrogen chloride and xylene sulfonic acid, and separating an acid sludge containing a substantial portion of the metal contaminant andcoke precursors originally present in said hydrocarbon oil. a

4; The process of claim 1 in which the lyst is silica-alumina.

5. The process of claim 1 in which the demetallization step includes regenerating the catalyst at about 950 to 1200" F contacting the regenerated catalyst with a molecular oxygen-containing gas at a temperature of about 1000to 1800 F., sulfiding the poisoning metal component in the catalyst by contact with a sulfiding agent at a temperature of about 500 to about 1500 R, chlorinating the poisoning metal containing component on the catalyst by contact with an essentially anhydrous chlorinating agent at a temperature of about 300 to 1000 F., contacting the catalyst with a liquid essentially aqueous medium ;to remove soluble poisoning metal chloride from the catayst.

6. The process of claim 5 in which the sulfiding is performed by contact with H 8.

7. The process of claim 5 in which the chlorinating is performed by contact with an equimolar mixture of C1 and CCl.;.

8. A process of treating a residual hydrocarbon oil boiling above the gasoline range and containing about 25 to about 500 p.p.m. nickel and about 50 to about 1000 p.p.m. vanadium, comprising the steps of treating said hydrocarbon in an acid treating zone with a non-oxidizing metaland -asphalt precipitating acid to reduce by about 50 to 90% the content of said contaminant metal, obtaining the treated oil from an acid sludge containing a substantial portion of said metal contaminant, removing the acid from the treated oil, fractionating the treated oil to remove components boiling below about 400 F., contacting the residual fraction boiling above about 400 F. and containing at least about 1 to about 25 p.p.m. nickel and at least about 2 to about 50 p.p.m. vanadium with a solid cracking catalyst under cracking conditions to produce gasoline, removing metal contaminated catalyst, the removed catalyst containing more than about 200 p.p.m. nickel and more than about 500 p.p.m. vanadium, demetallizing the removed catalyst to remove at least 50% of the nickel and at least 15% of the vanadium, returning the demetallized catalyst to said cracking system and re covering the product from said cracking.

9. The process of claim 8 in which the treatment with the non-oxidizing metaland -asphalt precipitating acid is conducted in the presence of a solvent for the hydrocarbon oil.

10. The process of claim 8 in which the acid is an anhydrous hydrogen halide.

1 1. The process of claim 10 in which the acid is HCI.

cracking cata- 12 The, process ofv claim 8 in: which the acid is ahydrocarbonsulfonic acid. I t I 13;, The process of claim;12 in which the acid .isxylene sulfonic acid. V I v 14-. The process-of claim :8 in whichlthesolvent is a liquidhydrojcarbon of 3- to: 7 carbon atoms.

15.? The process of claim 8 whereinthe residual hydrocarbon oili is treated with hydrogen chloride at elevated temperatures and pressures and. then extracted with npentane to form an acid-sludge raflinate and an-oil-extract Containing substantially less metal contaminant than said, I hydrocarbon oil. e

16. The process of claim8 whereinthe solid cracking catalyst is a synthetie gel silica-based cracking-catalyst;

17. The process of claim 8 wherein catalyst, demetallization includes contact ofthe catalyst with; a vapor reactive with ametal contaminan-t;

, 25 to about 500p.p.m. nickel and about 5.0 to about 1 000 p.p.m. vanadium; comprising the; steps of treating said hydrocarbon'in an acid treating zone with anon-oxidizing metaland -asphalt precipitating acid" to reduce by about 7 50 to 90% the content of said contaminantmetal, obtain- 7 fing the treated oil from an acid sludge containing a sub stant-ial portion of said mctalcontaminant; removing the acid from the treated oil, fractionatingi the treated oil to remove components boiling below about 400 F., contacting the residual fraetion boiling above about 400 F. t

, andfcontaiuing at least: about 1 to a eutzs' ppm. nickel and at least about 2 to about 50, ppm; vanadium with a solid cracking catalyst under cracking conditions to produce gasoline, removing metal contaminated catalyst from the; cracking system,v regenerating the catalyst at about 950 to 1200 F., contacting the regenerated catalyst with a molecular oxygen containing gas at a temperature of aboutlOOO tol800 F., sulfiding the poisoning metal component. on the catalyst by contact With H 8 at a temperature of about to 1500 F; chlorinating the poisoning metal containing component on the catalyst by contacting with an essentially anhydrous equimolar mixture of C1 and CCL, at a temperature of about 300 to 1000 F., contacting the'catalyst with'an'esse'ntially liquid aqueous medium to remove soluble poisoning metal chloride from the catalyst, returning the catalyst to said cracking system, the said demetallization removing about 50% of the nickel and at least about 15% of the vanadium, and recovering gasoline product from said cracking. 7 20. The process of claim 19 in which the treatment with the non-oxidizing metaland a'sph'alt precipitating acid is conducted in the presence of a solvent for thehydrocarbon oil., Y

' RetereneesCitedin the file of thisjpatent UNITED STA TES PATENTS 2,758,097 Doherty ct al.- Aug. 7, 1956 7 2,778,777 Powell Jan. 22, 1957 2,800,427 Junk et a1,; July 23, 1957 7 2,865,838' Mills Dec. 23, 1958 2,902,430 Kimberlin Q Sept. 1, 1959 2,948,675 cas et-al. Aug; 9, 1960 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,165,462 January 12, 1965 Bernard 8. Friedman et a1.

It is hereby certified that error appears in the above numbered pat- ,ent requiring correction and that the said Letters Patent should read as corrected be.1o*

Column 9, line 13, for "38,810" read 39,810

; line 63, for vandium" read-,- vanadium columnlO, line 37, for "chlorinatngjg' read chlorinating column 15, line 15, for "acfcaly st" read Catalyst column 16, line 58, for cracked" read cracker column 20, line 10, for "50" read 500 Signed and sealed this 16th day of November 1965 (SEAL) Attcst:

ERNEST W. SWIDER EDWARD J. BRENNER Commissioner of Patents Attesting Officer

Claims

1. A METHOD FOR PREPARING GASOLINE WHICH COMPRISES CONTACTING A HYDROCARBON CRACKING FEEDSTOCK BOILING ABOVE THE GASOLINE RANGE AND CONTAINING AT LEAST ABOUT 1 P.P.M. NICKEL AND AT LEAST ABOUT 1 P.P.M. VANADIUM BY INCLUDING IN SAID FEEDSTOCK THE RESIDUAL PRODUCT OBTAINED AS HEREAFTER SET FORTH, WITH A SOLID CRACKING CATALYST UNER CRACKING CONDITIONS TO PRODUCE GASOLINE, REMOVING FROM THE CRACKING SYSTEM CATALYST CONTAMINATED WITH METAL CONTAMINANT, THE REMOVED CATALYST CONTAINING AT LEAST ABOUT 50 P.P.M. NICKEL AND AT LEAST ABOUT 50 P.P.M. VANADIUM, DEMETALLIZING THE CATALYST TO REMOVE AT LEAST 50% OF THE NICKEL AND AT LEAST 15% OF THE VANADIUM FROM THE CATALYST, RETURNING THE CATALYST TO SAID CRACKING SYSTEM AND RECOVERING GASOLINE PRODUCIT FROMSAID CRACKING; SAID FEEDSTOCK CONTAINING THE RESIDUAL PRODUCT OBTAINED BY TREATING A MINERAL OIL HYDROCARBON BOILING ABOVE ABOUT 650*F. AND CONTAINING AT LEAST ABOUT 5 P.P.M. NICKEL AND AT LEAST ABOUT 5 P.P.M. VANADIUM WITH A METAL- AND -ASPHALT PRECIPITATING ACID TO REDUCE BY ABOUT 10 TO 90% THE CONTENT OF SAID CONTAMINANT, SAID RESIDUAL PRODUCT CONTAINING AT LEAST ABOUT 1 TO ABOUT 25 P.P.M. NICKEL AND AT LEAST ABOUT 2 TO ABOUT 50 P.P.M. VANADIUM AND LESS METAL CONTAINMENT THAN SAID MINERAL OIL HYDROCARBON.