2,702,232 Unite States Patent 0 C6 Patented Feb. 15, 1955 1 2 ing a slight excess of ammonium tungstate, in the 2,702,232 absence of air, brings about decomposition of the am monium tungstate with an apparent concomitant reduc METAL TUNGS‘TITES tion of the excess tungstic oxide to the blue oxide W203, Herrick R. Arnold, Wilmington, and James E. Carnahan, as indicated by the development of a faintly green colora New Castle, Del., assignors to E. I. du Pont de Nemours tion of the yellow tungstate. Analysis of the product & Company, Wilmington, Del., a corporation of Dela shows it to correspond to the composition ware NiWO4.0.055W2O3 No Drawing. Application January 30, 1951, 10 Example II Serial No. 208,662 A solution of 582 g." of cobaltous nitrate hexahydrate in 2500 cc. of water was added at the rate of 1000 cc. 5 Claims. (Cl. 23-51) per hour at room temperature, with stirring, to a solu This invention relates to new compositions of matter tion containing 2 mols of ammonium tungstate and to methods for their preparation. More particularly this invention relates to new chemical compoundsv con taining tungsten and to methods for preparing them. prepared by dissolving 562 g. of ammonium tungstate It is an object of this invention to provide new compo octahydrate, [(NH4)2W4O13.8H2O], in 2500 cc. of water sitions ofv matter. A further object is to provide new and 100 cc. of 28% aqueous ammonia. A lavender chemical compounds containing tungsten and methods colored precipitate was formed in a pH range of 7.4:07. for their preparation. A still further object is to pro— The precipitate was ?ltered without washing and dried. vide new catalytic compounds. Other objects will appear at 120° C. for 24 hours. The dried product, which was hereinafter. gel-like in structure, showed a typical conchoidal frac The objects of this invention are accomplished by the ture and a high absorptive capacity for moisture, was following new chemical compounds which are metal crushed and sized to 8 to 14 mesh and reduced in hy tungstites corresponding in composition to metal salts of drogen as follows: an acid having one of the formulae HzWOz and HzWOs. One hundred thirty seven grams (150 cc. of 8 to 14 In actual practice these tungstites are obtained by re mesh granules) was charged into a tubular reduction acting, in the presence of excess ammonia, stoichiometric ' furnace and reduced in a stream of hydrogen at a space proportions of normal ammonium tungstate with a salt velocity of 1000 volumes of gas per volume of catalyst of the metal whose tungstite is desired, washing the pre per hour and 450° C. for 24 hours. After the reduc cipitate which forms, ?ltering it, drying it, and then calcin tion cycle, the catalyst was cooled to room temperature ing it for from 4 to 24 hours at 350 to 500° C. The in hydrogen, ?ushed with nitrogen, and discharged from calcined material, in granular or powdered form, is then the reduction furnace to a receiver under nitrogen. The reduced in a hydrogen containing atmosphere at tem reduced catalyst corresponded by analysis to cobalt tung peratures ranging from room temperature up to 700° C., stite containing a slight excess of W203, as represented the heating being gradual and extending over a period by the composition CoWO3+0.2W2Os. The reduced cat varying from 2 to 100 hours depending upon the tem alyst was not spontaneously pyrophoric at room tem perature schedule used. ~ perature but on slight heating the product ignited with The invention is illustrated by preferred embodiments a bright glow and oxidized to cobalt tungstate. in the following examples. Example III Example I An ammonium tungstate solution containing 2 moles Four moles of ammonium tungstate [(NH4)2WO4] of tungsten was prepared by dissolving 553 grams of in a 10% aqueous solution, prepared by dissolving 1080 ammonium metatungstate [(NH4)2W4O13.7H2O] in 3 g. of ammonium paratungstate [(NH4)6W7024-6H20] in liters of water, and adding 182 grams (202.5 cc.) of 28% 7000 cc. of water and 310 cc. of 28% aqueous ammonia aqueous ammonia to convert the ammonium metatung at 85° C., was added with stirring to 4 moles of nickel state to normal ammonium tungstate [(NH4)2WO4]. nitrate in a 16% solution, prepared by dissolving 1163 To this solution was added with stirring at room tem~ g. of Ni(NO3)26H2O in 6000 cc. of water at 85° C. A perature a solution containing 2 moles of cupric nitrate pale green precipitate was formed in a slurry having a pH prepared by dissolving 483.3 grams of Cu(NO3)2.3H2O of approximately 6. The ‘pH of the slurry was adjusted in 3 liters of water. A light-blue precipitate formed in to 7 at 75 ° C. by addition of 404 cc. of 28% aqueous a slurry having a pH of 4.6. The pH of the slurry was ammonia. The resulting precipitate was washed, ?ltered, adjusted to 7.0 by addition of 122 cc. of 28% aqueous dried, and calcined at 400° C. The product thus ob ammonia. The resulting precipitate was washed, ?l tained was charged into a furnace and heat treated at tered, and dried at 120—130° C. The product was then 400° C. in a stream of nitrogen at a space velocity of reduced in a 3:1 ‘nitrogen-hydrogen gas mixture at 500 390 volumes of gas per volume of catalyst per hour for space velocity for 32 hours starting at room tempera 12 hours, cooled to room temperature in nitrogen, and 60 ture and increasing the temperature of reduction to 500° the product then reduced for 24-47 hours at 450—480° C. C. in 25 hours, holding the reduction temperature at in hydrogen at a ‘space velocity of 600-1000 volumes 500° C. in 5 hours, then cooling to room temperature, 9..“- of gas per volume of catalyst per hour. The reduced in hydrogen. The reduced product corresponded by product corresponded by analysis to nickel tungstite analysis to copper tungstite (CuWOz) as follows: (NiWOz) containing a slight excess of W203. Mag 65 netic measurements showed that essentially all the nickel ‘ Percent Percent Ratio, was present in a chemically combined state. The product Cu W Cu:W was not spontaneously pyrophoric when exposed to air at room temperature. On warming slightly over a Bunsen Calculated ______21.95 63.50 1: ?ame, however, the product ignited with a bright glow and 70 Found ______23. 50 62.35 1:0.93 oxidized to yellow nickel tungstate. X-ray diffraction ' analysis of the nickel tungstite indicated that metallic Example IV nickel and W02 were present in trace amounts while the major part of the mass was amorphous in character. An ammonium tungstate solution containing 2 moles The yellow product formed by precipitation from 75 of tungsten was prepared by dissolving 540 grams of equimolar solutions of nickel nitrate and ammonium ' ammonium metatungstate in 12 liters of water and add tungstate, after adjustment with excess ammonia to pH ing 155 cc. of 28% aqueous ammonia to convert the 7 and washing‘ and drying, corresponds by analysis to ammonium metatungstate to normal ammonium tung state [(NH4)2WO4]. > ‘ ' ~ nickel tungstate containing a slight excess of ammonium 80 To this solution was added with stirring at 55° C. a tungstate. Calcination of the nickel tungstate contain I \ solution containing 2 moles of ferrous chloride prepared 2,702,232 1% by dissolving 397.6 grams of FeCl24H2O in 3 liters of water-soluble salt of the metal whose tungstite is desired water. A dark olive-green precipitate was thus obtained may be used. Examples are copper sulfate, copper chlo in a slurry having a pH=7.0. The precipitate so formed ride, nickel sulfate, nickel chloride, nickel acetate, tho was ?ltered, washed and dried at 120—l30° C., and re rium nitrate, thorium chloride, manganese chloride, zinc duced at 40_0—500° C. for 32 hours in hydrogen at 1000 chloride, zinc sulfate, zinc permanganate, iron nitrate, space velocity. The reduced product corresponded by iron chloride, silver nitrate, cadmium chloride, cadmium analysis to iron tungstite (FeWOa) as follows: nitrate, stannous chloride, stannous ?uoride, stannic sul fate, cobalt nitrate, cobalt chloride and the like. Percent Percent Ratio, The tungstites of this invention are particularly useful Fe W Fe:W 10 as catalysts, especially for hydrogenation, dehydrogena tion, and dehydration reactions. They are especially

Calculated ______19. 40 03. 90 1:1 useful for the hydrogenation of carbon-carbon double Found ______19. 37 61. 32 1:0. 90 bonds and for reducing carbonyl groups, for example in the conversion of benzene to cyclohexane and of ace 16 tone to isopropanol. The tungstites of this invention are prepared by the The tungstites of this invention are catalysts also for carefully controlled reduction of the tungstate salts reactions in which hydroxyl compounds are added to which are prepared by precipitation in the presence of ole?ns. For example, they are effective in adding water excess ammonia by mixing suitable solutions of salts of to propylene and isobutylene yielding isopropanol and the desired metal and ammonium tungstate. 20 tertiary butanol as products, in adding ethanol to iso The tungstites of this invention occur in two series, butylene yielding ethyl tertiary butyl ether as product, the one corresponding to divalent tungsten and the other and in adding acetic acid to propylene yielding isopropyl corresponding to tetravalent tungsten, and are formally acetate as product. derived from the hypothetical acids HzWOz and HaWOa. As many apparently widely different embodiments of Speci?c tungstites, in addition to nickel and cobalt, iron 25 this invention may be made without departing from the and copper tungstites are zinc tungstite, silver tungstite, spirit and scope thereof, it is to be understood that this cadmium tungstite, manganese tungstite, tin tungstite, invention is not limited to the speci?c embodiments and the like. thereof except as de?ned in the appended claims. In some cases it is advantageous to prepare two or We claim: more tungstites simultaneously, thus obtaining them in 30 1. A metal tungstite in which the metal is selected intimate association, or to carry the reduction of the from the class consisting of nickel, cobalt, copper and tungstite salts to a point either somewhat beyond or iron and in which said metal is chemically combined before the precise tungstite stage, or to employ a slight with said tungsten in an atomic ratio of 1:1 and oxygen excess of one component in order to gain advantages is chemically combined with said tungsten in an atomic in catalyst performance, such as for example, enhanced ratio lower than in the tungstate of said metal and which activity or selectivity. is the product obtained by reacting ammonium tungstate As a rule the calcination step is conducted at tempera in aqueous ammonia with a water soluble salt of said tures‘ of from 350-500” C. for from 4 to 24 hours. metal, drying the resulting reaction product, and calcin Usually, however, the, calcination is carried on for no ing and reducing in hydrogen the dried product at a less than 12 hours or for more than 28 hours. 40 Lemperature of 400 to 500° C. for a period of at least 24 The reduction of the calcined product is effected with ours. hydrogen alone or with hydrogen admixed with a diluent 2. Nickel tungstite in which said nickel is chemically gas such as nitrogen at temperatures ranging from room combined with said tungsten in an atomic ratio of 1:1 temperature up to 700° C., the heating being gradual and oxygen is chemically combined with said tungsten and extending over a period ranging from 2 to 100 hours 45 in an atomic ratio lower than in nickel tungstate and depending upon the temperature scheduled used. Some which is the product obtained by reacting ammonium variations in the compositions of the tungstites may be tungstate in aqueous ammonia with a Water soluble salt effected by controlling the time and temperature of reduc of nickel, drying the resulting reaction product, and cal tion, but in any event the reduced products correspond cining and reducing in hydrogen the dried product at a in composition essentially to metal tungstites of an acid ; gemperature of 400 to 500° C. for a period of at least 24 of the general formula HzWOz and H2WO3. ours. Although in the examples ammonium paratungstate 3. Cobalt tungstite in which said cobalt is chemically has been used and converted to the normal tungstate combined with said tungsten in an atomic ratio of 1:1 by addition of ammonia to a pH of 7, this is only be and oxygen is chemically combined with said tungsten cause the ammonium paratungstate is more readily avail- I in an atomic ratio lower than in cobalt tungstate and able than the normal salt. If desired, however, the which is the product obtained by reacting ammonium normal salt can be used and the neutralization step tungstate in aqueous ammonia with a water soluble salt omitted. If desired also, ammonium metatungstate or of cobalt, drying the resulting reaction product, and cal sodium tungstate can be used, and these latter salts have cining and reducing in hydrogen the dried product at a some advantage in being more highly soluble in water 60 Lemperature of 400 to 500° C. for a period of at least 24 than either the normal tungstate or ammonium para ours. tungstate. 4. Copper tungstite in which said copper is chemically Precipitation of the desired metal tungstate for reduc combined with said tungsten in an atomic ratio of 1:1 tion to a tungstite can be effected either by adding a and oxygen is chemically combined with said tungsten solution of the metal nitrate to a solution of normal 65 in an atomic ratio lower than in copper tungstate and ammonium tungstate or alternatively by adding the nor which is the product obtained by reacting ammonium mal ammonium tungstate solution to a solution of the tungstate in aqueous ammonia with a water soluble salt metal nitrate. . of copper, drying the resulting reaction product, and cal Generally, the reaction between the ammonium tung cining and reducing in hydrogen the dried product at a state and the salt of the metal whose tungstite is desired 70 flemperature of 400 to 500° C. for a period of at least 24 is- effected at temperatures in the range of 60° to 80° C. ours. because of the low order of solubility of ammonium 5. Iron tungstite in which said iron is chemically paratungstate in water at ordinary temperatures. If a combined with said tungsten in an atomic ratio of 1:1 more soluble tungstate is used, such as ammonium meta and oxygen is chemically combined with said tungsten tungstate or sodium tungstate, then the reaction can be 75 in an atomic ratio lower than in iron tungstate and carried out at ordinary temperatures. For practical rea which is the product obtained by reacting ammonium sons it is desirable that the mixing of the solutions be tungstate in aqueous ammonia with a water soluble salt effected with good agitation, thus insuring the best con of iron, drying the resulting reaction product, and cal ditions for complete reaction. In some instances it is cining and reducing in hydrogen the dried product at a desirable to warm the/mixed solutions in order to bring 80 about coagulation of the precipitate formed and thus ltlemperature of 400 to 500° C. for a period of at least 24 make it easier to handle in the subsequent washing and ours. ?ltering operations. In the examples nickel and cobalt nitrates have been (References on following page) used but it is to be understood that in place thereof any 2,702,282 6 References Cited in the ?le of this patent hMellor, l(égalinprehensive1 'lliieaiigel 0T1: InorganicG and UNITED STATES PATENTS Tand eoretica Co., N. Y.,emistry, pages 745-752.v0 . , 3 , ongmans, reen. ’ 2,145,745 Armstrong ______Jan. 31, 1939 Metallography, Dowdell, Jerabeck, Forsyth, Green, 2,339,888 Smith ______Aug. 8, 1942 5 10111; vggeyson Ltda, C129143, pagesé? 4. R bb c an 00 ysics an emistry, em. u er 0., OTHER REFERENCES Cleveland, Ohio, 1943, pages 376, 380. Ho?man, Lexikon der Anorganischen Verbindungen, Li and Wang “Tungsten” A. C. D. monograph, No. Band 2, No. 56-81 Bibliographien, Liepzig 1912-1914, 94, Reinhold Publishing Corp., N. Y., 1947, pages 193, pages 728, 729, 730, 761 and 762. 10 194, 196, 197, 257, 272, 273, 291. Dana System of Mineralogy, vol. 1, pages 605-606, Wiley and Co., N. Y., 1944.