United States Patent 0 ICC Patented August 30, 1966
Total Page：16
File Type：pdf, Size：1020Kb
1 3,269,957 United States Patent 0 ICC Patented August 30, 1966 1 2 When the tin and antimony compounds in the mixture 3,269 957 are presentin the lower valency state, i.e. as divalent tin STABILIIZED ANTIMONY-TIN OXIDE CATALYSTS or trivalent antimony compounds, it is particularly pre James Robert Bethell, Epsom Downs, England, assignor ferred to subject the mixture to a preliminary heat-treat to The Distillers Company Limited, Edinburgh, Scot ment in an atmosphere comprising oxygen and an inert land, a British company No Drawing. Filed May 15, 1963, Ser. No. 280,721 gas such as nitrogen, carbon dioxide or steam, the tem Claims priority, application Great Britain, May 23, 1962, perature being controlled so that no part of the catalyst 19,749/62 during this preliminary heat-treatment exceeds a tempera 3 Claims. (Cl. 252-437) ture of about 650° C.; in this way loss of the lower 10 valent metallic compounds by volatilization is avoided. This invention relates to catalytic compositions and in A convenient way of doing this is to heat pellets of the particular to catalytic compositions for use in oxidation catalyst in a furnace, the temperature of which is raised reactions. from about 300° to about 650° C. over a period of not According to the present invention a catalyst compo less than about 8 hours, while passing steam of air‘ sition suitable for catalysing the vapour phase oxidation 15 over the catalyst. After this preliminary heat-treatment of hydrocarbons comprises a material selected ‘from the the mixture is then subjected to a ?nal heat-treatment in group consisting of antimony tetroxide admixed with stan air at a temperature in the range 550° to 1100" C. nic oxide and a composition constituted by antimony, tin The atomic ratio of tin to antimony in the catalytic and oxygen and is stabilised by the addition of a com composition may vary within moderately wide limits, for pound of bismuth. instance between 0.121 and 20:1, although compositions The catalytic composition may be regarded either as containing proportions of tin to antimony outside this a mixture of antimony tetroxide with stannic oxide or as range may be useful for some purposes. a compound of antimony, tin and oxygen, e.g., tin anti By whichever method the oxides or hydrated oxides have monate; under the reaction conditions either or both been prepared, the mechanical stability of the ?nished forms may be present. 25 catalyst is enhanced by washing, preferably with water The catalytic composition may be prepared from any of before drying. the oxides of antimony and tin, or from compounds of The catalyst composition may be used for catalysing tin or antimony which on heating in the presence of an the vapour phase oxidation of organic hydrocarbons, pro oxygen~containing gas, such as air, are converted to the duction of acrylonitrile and methacrylonitrile by vapour oxides provided the ?nal composition contains antimony 30 phase reaction at elevated temperature of propylene or tetroxide and stannic oxide. Oxides of antimony and tin, isobutene with oxygen and ammonia, and the production or substances yielding these oxides, which may be used of acrolein or propylene, hydrogen cyanide from meth~ in the manufacture of the catalytic composition include anol and ammonia, and diole?ns from mono-ole?ns. antimony trioxide, antimony tetroxide, antimony pentox In carrying out reactions of this type on the industrial ide or mixtures of such oxides; stannic oxide, stannous 35 scale for reasons of economy the life of the catalyst is of oxide, or mixtures of such oxides. Hydrated forms of considerable importance. It is known that under certain these oxides may also be used, for instance, such as are operating conditions, the above catalysts may slowly lose formed by the action of aqueous nitric acid on antimony part of their activity. The loss of activity may, for ex or tin metals or on mixtures of the metals. The catalyst ample, be due to the deposition of carbon or organic may be prepared for instance by mixing together any of 40 material on the surface of the catalyst. the oxides of antimony and tin, or substances yielding It has now been found that this loss of activity may these oxides, and subjecting the mixture to a heat-treat be prevented or substantially reduced and the life of the ment in the presence of an oxygen containing gas such as catalyst thereby increased by the addition of the metal air, for instance at a temperature between 550° and 1100° compound speci?ed above to the catalytic composition. C. Where the initial components are antimony tetroxide 45 The addition of bismuth to the catalytic composition and stannic oxide themselves, it is still preferred to sub may be made in any suitable manner and at any time but ject the mixture to a prior heat-treatment with or without preferably during the preparation of the catalyst, and oxygen for instance at a temperature between 550° and before the ?nal drying thereof. Bismuth may be added 1100° C. in the form of its oxide or as compounds which undergo A particularly preferred method of preparing the anti 50 thermal decomposition to the oxides during the prelimi mony oxide/tin oxide catalytic composition comprises in nary heat treatment or at the temperatures employed for timately mixing stannic oxide or the hydrated oxide ob the reaction e.g. metal nitrates or formates or as non tained by the action of aqueous nitric acid on tin metal, decomposable salts such as for example phosphates, molyb_ with antimony pentoxide, antimony tetroxide, or the hy dates or phosphomolybda-tes. Preferably the addition is drated oxide formed by the action of aqueous nitric acid 55 made by slurrying the ?lter cake, produced after ?ltering on antimony metal and heat-treating the resulting mix and washing the catalyst mixture, with a solution or slurry ture at 550° to 1100‘0 C. in the presence of an oxygen of the oxide or compound of the metal and subsequently containing gas such as air. drying, and if desired, pelleting the resultant mixture. Another preferred method of preparing the antimony The proportions of bismuth incorporated in the cata oxide/tin oxide catalytic composition comprises hydro 60 lyst composition may vary according to the precise de lysing with water cationic salts of the metals, such as the gree of hardness and other properties of the catalyst de chlorides, and recovering and heating the resulting precipi sired. Generally, incorporation of about 2% on a molar tate. To obtain complete hydrolysis it may be necessary basis of the additive is su?icient. to add a volatile base such as ammonia. Either or both The manufacture and use of the catalyst of the present of the metal oxide components of the composition may 65 invention is further illustrated (but in no way limited) by be prepared in this way. Particularly useful catalytic the following example, in which all parts referred to are compositions can be prepared by this method from stannic parts by weight. chloride and antimony pentachloride by mixing them to Example gether in aqueous media and adding ammonia until the 14.8 parts of powdered tin was added in small portions pH is greater than 5.0, recovering the precipitate and heat 70 over 30 minutes to a boiling solution of 44 parts of nitric ing it at a temperature between 550° and 1100° C. acid (8.6. 1.42) in 350 parts of water. 60.9 parts of 3,269,957 3 4 powdered antimony (60.0 p.b.w.) ‘was added in small said material being stabilized by the addition of an oxide portion over 30 minutes to 176 parts of concentrated of bismuth, the amount of the oxide being present in an nitric acid (SC. 1.42) at 95—100° C. Both mixtures were effective amount up to about 2% on a molar basis sub boiled for 15 minutes, mixed and boiled again for 15 stantially to reduce loss of catalyst activity and thereby minutes. The suspension was cooled to 40° C. the super increase the life of the catalyst. natant liquid removed and the solid resuspended in 500 2. The catalytic composition of claim 1 wherein the parts of water and stirred for 15 minutes. The mixture ratio of tin to antimony is between about 01:1 and about 'was allowed to settle, the supernatant liquid removed and 20:1. once again resuspended in 500 parts of water. The mix 3. The catalytic composition of claim 1 wherein the ture was boiled, with stirring for 1 hour, cooled to 40° C. metal oxide is formed by the heat treatment of a com and the liquid removed as before. The resuspension in pound selected from the group consisting of the nitrate, cold water was then repeated and the solid ?nally col formate, molybdate, phosphate, and phosphomolybdate lected on a ?lter. of said metal. 2.91 parts of bismuth trioxide was made into a slurry with a little ‘water and added to a slurry of the above References Cited by the Examiner solid. The mixture was thoroughly stirred, dried, ?rst UNITED STATES PATENTS on a steam bath and then in an oven at 120° C. The dry solid was sieved to pass 30 mesh 3.5.8., 1% w./w. graph 2,904,580 9/1959 Idol ____________ __ 260—465.3 ite added and made into 3 pellets. 2,941,007 6/ 1960 Callahan _________ __ 260-604 A gaseous mixture of 10% butene-2, 50% v./v. air and 3,044,965 7/1962 Callahan _________ __ 252-456 40% v./v.