US3210293A - Hydrorefining catalyst base prepared by high ph precipitation - Google Patents

Description

United States Patent 3,210,293 HYDROREFINING CATALYST BASE PREPARED BY HIGH pH PREfiIPITATION Mark J. OHara, Mount Prospect, 11]., assignor t0 Universai Oil Products Company, Des Piaines, IlL, a corporation of Delaware N 0 Drawing. Filed July 25, 1962, Ser. No. 212,460

9 Claims. (Cl. 252-453) This invention relates to an improved hydrorefining catalyst for upgrading heavy hydrocarbon stocks in the presence of hydrogen. More particularly, this invention is directed to the preparation of a catalytic composite having superior activity toward the removal and/or conversion of various types of impurities, as hereinafter described, in heavy hydrocarbon stocks such as total crude oil, crude residua, atmospheric and vacuum gas oils, cycle oils, etc., as well as superior activity in hydrocracking such heavy stock to gasoline or middle distillates with minimum gas production.

Crude petroleum oil, topped crude, and other heavy hydrocarbon fractions and/or distillates derived therefrom contain various non-metallic and metallic impurities. Among the non-metallic impurities are nitrogen, sulfur and oxygen which exist in heteroatomic compounds and are often present in relatively large quantities. Nitrogen is undesirable because it rapidly poisons various catalysts which may be employed in the conversion of petroleum fractions; in particular, nitrogen must often be removed from catalytic hydrocracking charge stocks. Nitrogen and sulfur are also objectionable because combustion of hydrocarbonaceous fuels containing these impurities releases nitrogen and sulfur oxides which are noxious, corrosive and present a serious problem in the field of air pollution. Sulfur, of course, is deleterious in motor fuel because of odor, gum formation and decreased lead susceptibility.

Another class of undesirable constituents found in crude oil and residual oils are asphaltenes which are non-distillable, oil-insoluble, high molecular weight coke precursors containing sulfur, nitrogen, oxygen and metals; they are colloidally dispersed in raw crude oil but when subjected to heat, as in vacuum distillation, the asphaltenes flocculate and polymerize thereby making their conversion to more valuable oil-soluble products extremely diificult; thus, in the heavy bottoms from a reduced crude vacuum distillation column, the polymerized asphaltenes are solid materials at ambient temperature. Such product is useful only as road asphalt or, when cut back with middle distillates, as low grade fuel and commands a price substantially below that of the raw crude oil itself.

The most common metallic contaminants are nickel and vanadium, although other metals including iron, cop per and zinc are often present. The metals may occur as suspended metal oxides or sulfides or water-soluble salts which may be removed, at least in part, by filtration, waterwashing; electric desalting, or other fairly simple physical means; mainly, however, the metals occur as thermally stable metallo-organic complexes such as metal porphyrins and derivatives thereof. Most of the metallo-organic complexes are linked with the asphaltenes and become concentrated in residual fractions; other metallo-organic complexes are volatile, oil-soluble, and are therefore carried over in distillate fractions. Reducing the concentration of the metallo-organic complexes is not easily achieved, at least to the extent that the crude oil or other heavy hydrocarbon charge stock may be made suitable for further processing. Even though the concentration of these metallo-organic complexes may be relatively small in distillate oils, for example, often less than about 10 ppm. as the elemental metal, subsequent processing techniques are often adversely affected thereby. For example, when a hydrocarbon charge stock containing metalloorganic compounds, such as metal porphyrins, in excess of about 3.0 ppm. calculated as the elemental metal, is subjected to hydrocracking or catalytic cracking for the purpose of producing lower-boiling components, the metals deposit upon the catalyst and the concentration thereof increases with time. Since vanadium and the iron group metals favor dehydrogenation activity at usual cracking temperatures, the resulting contaminated hydrocracking or cracking catalyst produces increasingly excessive amounts of coke, hydrogen and light hydrocarbon gases at the expense of more valuable liquid product until eventually the catalyst must be subjected to elaborate regeneration techniques or be replaced with fresh catalyst. The presence of excessive quantities of metallo-organic complexes adversely affects other processes including catalytic reforming, isomerization, hydrodealkylation, etc. Vanadium itself is also objectionable in heavy fuel oils and residual solids used as fuels because vanadium pentoxide formed during combustion is a strong acid at high temperature and will corrode the refractory lining, tube supports and other internal hardware of a fired heater utilizing such fuel.

The removal and/or conversion of these impurities is most effectively carried out by catalytic hydrorefining whereby a heavy oil charge containing one or more of these impurities is contacted with a catalyst under hydrorefining conditions; hydrorefining conditions include a temperature below the thermal cracking temperature of the charge and generally in the range of 650950 F., a pressure in excess of about 500 p.s.i.g. and usually in the range of 10003000 p.s.i.g., and the presence of hydrogen in an amount ranging from WOO-300,000 standard cubic feet per barrel of charge. These conditions in conjunction with a suitable catalyst promote mild hydrogenation and thermal hydrocracking reactions whereby nitrogen, sulfur and oxygen are converted to ammonia, hydrogen sulfide and water respectively, oil-insoluble asphaltenes are cracked and hydrogenated to yield lower boiling oilsoluble hydrocarbons, and'nickel, vanadium and other metals which may be present are deposited out on the catalyst or concentrated in polymerized organic sludge formed as a lay-product. In some cases, depending on process conditions and the nature of the charge, a substantial portion of the heavy oil charge may be simultaneously hydrocracked to yield gasoline, kerosene, fuel oil or other valuable liquid products; in other cases, the major proportion of the oil charge may pass through the hydrorefining zone virtually unchanged except for a sub stantial reduction in the concentration of metals, sulfur, nitrogen, oxygen, and oil-insoluble asphaltenes.

Hydrorefining catalysts constitute two broad classes: unsupported catalysts and supported catalysts. It is the latter type with which the present invention is concerned. Supported catalysts can be generically characterized as comprising a metallic component having hydrogenation activity, composited with a refractory inorganic oxide carrier of synthetic or natural origin and having a medium-to-high surface area and a well-developed pure structure. Metallic components having hydrogen activity include the metals of Groups VB, VHS, and VIII of the Periodic Table. In addition to hydrogenation activity, an effective supported hydro-refining catalyst should also possess acidity or contain acid-acting sites to provide some measure of cracking activity. The cracking activity can be furnished by way of the refractory oxide carrier which then contributes catalytic effects as well as functioning as a support. In particular, it has been found that a hydrorefining catalyst comprising alumina and silica demonstrates superior activity and stability over catalysts comprising other types of supports.

The present invention is particularly directed to a novel method of preparing the alumina-silica support. The simplest and most widely employed preparatory techniques involve precipitation wherein (1) one of the oxides (alumnia or silica) is precipitated from a sol, impregnated with a solution of the other oxide and then the latter is precipitated of (2) both oxides are co-precipitated. The prior art has taught that such precipitations should be effected in mediums ranging from strongly acid to neutral, typically at a pH range of about 3-7.5. I have now discovered that, in relation to the art of catalytic ihydrorefining of heavy oils greatly improved results obtain Where the alumina-silica complex forming the carrier for the hydrorefining catalyst is precipitated at a high pH ranging from moderately to strongly alkaline.

A broad embodiment of the invention relates to a method of preparing an alumina-silica composite which comprises forming an acidic hydrosol of alumina and silica and precipitating an alumina-silica hydrogel therefrom at a pH above about 7.9, and more particularly at a pH in the range of about 8-13.

A more specific embodiment of this invention is directed to a method of preparing an alumina-silica composite which comprises forming an acidic hydrosol of alumina and silica and precipitating an alumina-silica hydrogel therefrom by adding said hydrosol to excess alkaline precipitant so that the precipitation is substantially completed at a pH in the range of about 8-13, the hydrogel containing on a dry basis about 50-90% by weight of alumina.

A further specific embodiment of this invention concerns a method of preparing a hydrorefining catalyst which comprises forming an acidic hydrosol of alumina and silica, precipitating an alumina-silica hydrogel therefrom at a pH above about 7.9, commingling the hydrogel with at least one metallic component selected from the metals and compounds of the metals of Groups VB, VB, and VIII of the Periodic Table, and thereafter drying the resulting metal-containing hydrogel.

The initial step of this invention involves the formation of a silica-alumina hydrosol. It is most convenient to separately prepare an acidic silica sol and an alumina sol, each having the desired concentration of silica and aluminum i-on respectively, and then commingle the two sols in the desired proportions. The instant method is especially well suited to the preparation of high alumina composites containing 50% :or more by weight of alumina. Several alternative procedures are available for preparing the acidic silica sol. In one method, a suitable mineral acid such as hydrochloric acid, sulfuric acid, or nitric acid is added to an aqueous solution of an alkali metal silicate, sodium silicate being preferred because of its low cost and wide availability. In a second method, the order of addition is reversed, the water glass being added to the acid; this technique is preferred since the formation of the silica sol always occurs under acid conditions and there is no danger of the sol prematurely solidifying as is the case in the former method when the pH of the system is being reduced from a high value to a low value. When using hydrochloric or sulfuric acid, concentrations thereof from about 10% and to about 30% are satisfactory. The water glass solution may be prepared from commercial sodium silicates such as Philadelphia Quartz Company brands E, M, N, or S; the commercial water glass is first diluted with water to reduce the SiO concentration thereof to about 5%-15% by weight. The commingling of acid and Water glass is preferably carried out with agitation and at a temperature below about 95 F. The pH of the acidic silica sol at this stage will be in the range of 1.5-2. If desired, the silica sol may be aged at this pH for a period of 0.1-1 hour or more.

The aluminum may be added to the silica sol as an aqueous salt solution thereof comprising, for example, aluminum sulfate, aluminum chloride, or aluminum nitrate. Preferably, however, a true alumina sol should be employed which may be obtained, for example, by digesting pure aluminum slugs or pellets in hydrochloric acid, preferably adjusting the Al/Cl ratio thereof to within specified limits, and if desired a neutralizing agent such as urea or urea and hexamethylenetetramine together may be added. The alumina sol may contain about 10-20% by weight of aluminum and may have a corresponding Al/Cl weight ratio of about 1-1.5. If desired, the alumina sol may be aged for a period of 0.1-1 hour or more before it is mixed with the silica sol.

The separately formulated silica and alumina sols are then blended to yield an acidic hydrosol of alumina and silica. The alumina sol may be added to the silica sol, or the silica sol may be added to the alumina sol, or both may be continuously admixed as with an in-line blender. The mixing should be done with agitation and with water addition, if necessary, to prevent premature gelation at this point, since the blended sol is undergoing some polymerization and its viscosity increases. The pH of the blended sol will be about 2-3.5.

The alumina and silica are then coprecipitated from the blended hydrosol by carrying out the precipitation under conditions such that it is substantially completed at a pH greater than about 7.9 and preferably at a pH in the range of from about 8 to about 13. This may be accomplished by adding the alumina-silica hydrosol with agitation to a liquid body of alkaline precipitant, preferably an excess amount of alkaline preciptant, so that no local precipitation can occur at a pH below about 7.9. A preferred alkaline precipitant is ammonium hydroxide; other suitable alkaline precipitants include aqueous solutions of alkali metal hydroxides and carbonates such as NaOH, KOH, Na CO K CO ammonium bicarbonate; organic bases including quarternary ammonium hydroxides, guanidine, and aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, methylethylamine, etc. The rate of addition of the aluminasilica sol to the basic precipitant may be controlled so that the sol is immediately dispersed and precipitated. The alumina-silica sol may be added as a fine spray to guard against any precipitation in a low pH range. With respect to batch type operation, the pH at the beginning of the precipitation may be fairly high, for example in the range of 10-13, but decreases during the course of the precipitation as hydroxyl ions are neutralized. It should be noted that the foregoing precipitation procedure is just the converse of conventional methods wherein ammonium hydroxide, for example, is added to the acidic alumina-silica sol, in which latter event the great bulk of the precipitation is effected at a pH of 3-7. Without intending to limit this invention by theoretical considerations, the high pH precipitation is belived to provide a much higher percentage of pores having diameters above A. which are advantageous in the processing of stocks containing large molecules.

The resulting alumina-silica precipitate, which is a gelatinous complex or hydrogel, is then filtered from the mother liquor and washed to remove alkali metal ions, anions and excess alkaline precipitant. The Washing preferably comprises a wash with a dilute (0.01-0.2%) ammonium salt solution, such as ammonium chloride or ammonium nitrate, at a temperature of about -210 F. to facilitate alkali metal ion removal. The washed alumina-silica hydrogel is then dried, preferably at a temperature below that at which the chemically bound water is removed; that is, the drying procedure is effected at a temperature which conveniently removes the excess Water of formation but which permits the combined, chemically bound water to remain Within the hydrogel. Thus, the drying of the hydrogel is effected over a period of from about 1 to about 24 hours at a temperature not substantially greater than about 325 F. and preferably in the range of about ZOO-300 F. Although the alumina-silica hydrogel may be calcined before impregnation With the hydrogenatively active metal, a superior catalyst results where the dried uncalcined base is impregnated with the hydrogenatively active metal and then the total catalytic composite is subjected to a high temperature calcination in a free oxygen-containing atmosphere.

In a preferred method, therefore, the dried uncalcined alumina-silica hydrogel is then composited with one or more hydrogenatively active metallic components. Suitable hydrogenatively active metallic components include the metals and compounds of the metals of Groups VB, VB, and VIII of the Periodic Table; the Periodic Table referred to herein is that contained in the Handbook of Chemistry and Physics, 39th Edition, Chemical Rubber Publishing Company (1957-58). The term metallic component connotes those components of the cataytic composite which are employed for their catalytic activity toward hydrogenation, thereby distinguishing the same from those components utilized as the carrier material. Exemplary metallic components therefore include vanadium, chromium, molybdenum, tungsten, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum. The present catalyst may comprise any one or combination of any number of such metals which may exist in the elemental state or as the oxides or sulfides thereof in varying degrees of oxidation. The catalytic concentration of the metallic component or components, stated here on the basis of the elemental metal, will depend primarily on the particular metal involved; for example, the Group V and Group VI metals are preferably present in an amount Within the range of about 1-20% by weight, the iron group metals in an amount Within the range of about 02-10%, and the platinum group metals in an amount within the range of about 0.015%. The catalytically active metallic component is most easily composited with the alumina-silica hydrogel by impregnating the latter with an aqueous solution of a Watersoluble compound of the desired metal or metals; suitable compounds therefore include, but not by way of limitation, ammonium molybdate, ammonium tungstate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, dinitrito diamino platinum, chloroplatinic acid, chloropalladic acid, etc. Where two or more metallic components are employed, these may be incorporated into the final composite in a single or in successive impregnations.

The metal impregnated alumina-silica gel is then dried at a temperature of about 150-325 F. for a period of about 1 to about 24 hours. The dried composite, containing combined chemically bound water, is then subjected to a high temperature calcination in a free oxygencontaining atmosphere at an elevated temperature within the range of from about 400 F. to about 1400 F. Following the calcination treatment, the composite may be further treated for the purpose of causing the metallic components to exist within the composite in some combined form, such as the oxides, the sulfides, or in the elemental state. The utilization of a catalytic composite in which the active metallic components exist as the sulfides thereof is often preferred in many instances; such catalysts do not have the propensity to promote a temperature runaway whereby the catalytic composite may suffer rapid initial deactivation at the outset of the process in which the same is being utilized. The sulfiding of the catalytic composite may be effected in any suitable manner, utilizing sulfur-containing compounds such as hydrogen sulfide, carbon disulfide, tertiary butyl mercaptan, etc.

A hydrorefining process utilizing the catalyst prepared in accordance with the method of the present invention may be conducted in one or more reaction zones in which the catalyst may be disposed in the form of a slurry, a finely dispersed suspension, a fixed-fluidized bed, or a moving fluidized bed. Many types of heavy hydrocarbon oils may be treated by means of the present catalyst including full boiling range petroleum crude oils, topped or reduced crude oils, atmospheric distillates, heavy cycle oils from thermally or catalytically cracked stock,

light vacuum gas oils, heavy vacuum gas oils, and the like. The heavy hydrocarbon charge may be contacted with the catalyst entirely in the liquid phase or as a liquid-vapor mixture. The reaction zone or zones are maintained under an imposed pressure in excess of about 500 p.s.i.g. with an upper economic limit of about 5000 p.s.i.g. the preferred pressure range being about 1000- 3000 p.s.i.g. The feed stock is heated, in the presence or absence of hydrogen and with or without partial feed vaporization, introduced into the reaction zone containing the catalyst together with hydrogen at the rate of about 5,000300,000 standard cubic feet of hydrogen per barrel of total oil charged, and therein contacted with the hydrogen and catalyst at a temperature in the range of about 650-950 F. The weight ratio of oil charged to catalyst present in the reaction zone (weight hourly space velocity) should be in the range of about 0.2520 pounds of oil per pound of catalyst per hour and preferably about 1-10 pounds of oil per pound of catalyst per hour. Net hydrogen consumption will vary from about 200 to about 2,000 standard cubic feet of hydrogen per barrel of charge depending upon the nature of the latter and the specific hydrorefining conditions employed. Such hydrorefining treatment removes impurities, as hereinabove discussed, and may also convert the heavy oil charge via thermal hydrocracking to gasoline, kerosene, fuel oil and other valuable liquid products of reduced molecular weight.

The following example is given to illustrate the method of the present invention and the effectiveness of catalytic composites employed therein for the removal of nitrogen, C -insoluble asphaltenes and other impurities. It is not intended that the present invention be unduly limited to the catalyst, charge stock, and/ or operating conditions set forth in the example.

EXAMPLE Two catalyst samples, designated herein as Catalyst A and Catalyst B, were prepared as set forth below and tested in a continuous suspensoid process pilot plant. Catalysts A and B had identical compositions: 2% nickel and 16% molybdenum on an alumina-silica carrier consisting of 63% aluminum and 37% silica, all percentages being by weight and computed on a dry basis. However, the alumina-silica support of Catalyst A was precipitated at a low pH of 3-7 whereas the alumina-silica support of catalyst B was precipitated at a high pH of 10-8.

Catalyst A was prepared as follows: 304 milliliters of 12N HCI were diluted with 900 milliliters of water. 1,064 grams of Philadelphia Quartz Company Brand N water glass (28% SiO was diluted with 3,000 milliliters of water and added with stirring to the hydrochloric acid solution to yield an acidic silica sol. The silica sol was then added to 2,000 grams of alumina sol (an Al-Cl hydrosol containing 14.1% by weight of aluminum and having an AlzCl ratio of about 1.2) plus 6 liters of water and stirred for 15 minutes. The resulting alumina-silica sol had a pH of 3. 500 milliliters of 15 N ammonium hydroxide plus 500 milliliters of water were then added slowly with vigorous stirring to the alumina-silica sol. The final pH was 7.5. The resulting alumina-silica hydrogel was filtered, washed for 16 hours at 195 F. with about 3 gallons of water per hour. The washed hydrogel was then dried at 230 F. for a period of 16 hours. 135 grams of molybdic acid M00 were dissolved in 400 milliliters of water plus milliliters of 15 N ammonium hydroxide. 46 grams of were dissolved in 42 milliliters of 15 N ammonium hydroxide and added to the ammonium molybdate solution. The entire Ni-Mo solution was then diluted to 900 milliliters with water and poured over 500 grams of the dried alumina-silica hydrogel. The impregnated alumina-silica carrier was dried in a rotating steam drier and 7 then oxidized for 1 hour in a muffle furnace at a temperature of 1100 F.

Catalyst B was prepared as follows: 360 milliliters of 12 N HCl was diluted with 1300 milliliters of water. 1260 grams of Philadelphia Quartz Company Brand N water glass was diluted with 2525 milliliters of water and added to the hydrochloric acid solution with stirring. 2370 grams of alumina sol (an Al-Cl hydrosol containing 14.1% by weight of aluminum and having an AlzCl ratio of about 1.2) was diluted with 4 liters of water and added to the acidic silica sol. The alumina silica sol was then carefully added with agitation to a solution contaning 700 milliliters of 15 N ammonium hydroxide and 4 liters of water. The pH at the beginning of the precipitation was about 10 and the pH at the completion of the precipitation was 8.2. The gel was filtered and then washed for 16 hours at 190 F. with about 3 gallons of water per hour. The gel was then dried for 16 hours at a temperature of 230 F. 145 grams of molybdic acid (85% M were dissolved in 300 liters of water plus 125 milliliters of 15 N ammonium hydroxide. 49 grams of Ni(NO .6H O were dissolved in 45 milliliters of 15 N ammonium hydroxide and this solution was .mixed with the ammonium molybdate solution. The entire Ni-Mo solution was then diluted to 900 milliliters with water and poured over 500 grams of the dried alumina-silica hydrogel. The impregnated alumina-silica carrier was dried in a rotating steam drier and then oxidized for one hour in a muflle furnace at a temperature of 1100" F.

These catalyst samples were individually evaluated in a continuous slurry pilot plant utilizing a Wyoming sour crude oil as the charge stock thereto. The Wyoming sour crude oil had a gravity of 22 API and contained 2700 p.p.m. total nitrogen, 2.8% by weight of sulfur, 100 p.p.m. total metals (Ni-l-V) and 8.3% by weight of C -insoluble asphaltenes. The catalyst was ground to 200 mesh size, slurried with the crude oil charge and pumped to a stirred reactor having a capacity of 150 milliliters. The crude oil: catalyst weight ratio was and the crude-powdered catalyst slurry was pumped to the reactor at the rate of 50 milliliters per hour. Hydrogen was added to the reactor at the rate of 20,000 standard cubic feet per barrel of charge. The reaction temperature was maintained at 775 F. and the total pressure at 2000 p.s.i.g. The duration of each run, after achieving a lined-out operation, was at least 96 hours. The hydrogen was separated from the effluent and recycled, and the liquid product was recovered and analyzed for total nitrogen, total metals (by spectrographic emission), sulfur, and C -insolubles. A comparison of the impurities concentration of the liquid product as between Catalyst A and Catalyst B is given in Table I:

1 Catalyst Acarrier precipitated at pH of 3-7.

Catalyst Bcarrier precipitated at pH of 108.

It will be seen that the total nitrogen of the product resulting from the use of Catalyst B, whose aluminasilica base was precipitated at a high pH in accordance with this invention, was only about one-fifth the total nitrogen of the Catalyst A product whose alumina-silica base was precipitated at a conventionally low pH. It is also evident that Catalyst B reduced the C -insoluble content of the product to 0.1% as against 0.4% for Catalyst A. It will be apparent to those skilled in the art of petroleum processing, and particularly to those having knowledge of the difliculties inherent in the initial treating of crude oil and other heavy hydrocarbon charge stocks, that the utilization of the catalyst prepared in accordance with the method of this invention affords unusual benefits and advantages.

A hydrorefining process utilizing the instant catalyst is the subject of my application Serial No. 421,627 filed December 28, 1964.

I claim as my invention:

1. The method of preparing an alumina-silica composite which comprises forming an acidic hydrosol of alumina and silica, adding said hydrosol with agitation to a liquid body of alkaline precipitant and precipitating an alumina-silica hydrogel therefrom at a pH greater than about 7.9.

2. The method of preparing an alumina-silica composite which comprises forming an acidic hydrosol containing a major proportion of alumina and a minor proportion of silica and precipitating an alumina-silica hydrogel therefrom by adding said hydrosol with agitation to a liquid body of alkaline precipitant so that the pre cipitation is substantially completed at a pH greater than about 7.9.

3. The method of claim 2 further characterized in that said alkaline precipitant is ammonium hydroxide.

4. The method of preparing an alumina-silica composite which comprises forming an acidic hydrosol of alumina and silica and precipitating an alumina-silica hydrogel therefrom by adding said hydrosol with agitation to a liquid body of alkaline precipitant so that the precipatation is substantially completed at a pH in the range of about 8-13, the hydrogel containing on a dry basis about 5090% by weight of alumina.

5. The method of preparing a hydrorefining catalyst which comprises forming an acidic hydrosol of alumina and silica, adding said hydrosol with agitation to a liquid body of alkaline precipitant and precipitating an aluminasilica hydrogel therefrom at a. pH about about 7.9, commingling the hydrogel with at least one metallic component selected from the metals and compounds of the metals of Groups VB, VIB, and VIII of the Periodic Table, and thereafter drying the resulting metal-containing hydrogel.

6. The method of preparing a hydrorefining catalyst which comprises forming an acidic hydrosol of alumina and silica, adding said hydrosol with agitation to a liquid body of alkaline precipitant and precipitating an aluminasilica hydrogel therefrom at a pH in the range of about 8-13, impregnating the hydrogel with at least one metallic component selected from the metals and compounds of the metals of Groups VB, VIB, and VIII of the Periodic Table, and thereafter drying the impregnated hydrogel.

7. The method of claim 6 further characterized in that said metallic component comprises tungsten.

8. The method of claim 6 further characterized in that said metallic component comprises molybdenum.

9. The method of claim 6 further characterized in that said metallic component comprises nickel.

References Cited by the Examiner UNITED STATES PATENTS 2,348,647 5/44 Reeves et al 208- 2,352,484 6/44 Kanhofer 208-118 2,355,388 8/44 Michael et al. 208l11 2,905,636 9/59 Watkins et a1. 208216 3,094,480 6/63 Richardson 208-254 3,099,617 7/63 Tulleners 208109 ALPHONSO D. SULLIVAN, Primary Examiner.

Claims (1)

1. THE METHOD OF PREPARING AN ALUMINA-SILICA COMPOSITE WHICH COMPRISES FORMING AN ACIDIC HYDROSOL OF ALUMINA AND SILICA, ADDING SAID HYDROSOL WITH AGITATION TO A LIQUID BODY OF ALKALINE PRECIPITANT AND PRECIPITATING AN ALUMINA-SILICA HYDROGEL THEREFROM AT A PH GREATER THAN ABOUT 7.9.