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The surface state of SnO2-Sb2O4 catalysts
125 Oxonium
Salt Catalysts
Catalysts in Chemistry (R.H. Chandler Ltd.) occasionally publishes translations of important Russian or other articles and reviews of particular topics. Vol. 13, No.4 (1983) contains a biblioqraohv (bv D. Evton) which contains-short summaries of'23 recent articles and patents in which the use of oxonium salts as catalysts is described. These salt&of general formula R3OX, especially salts such as triethvl oxonium tetrafluoroborate (Et30BF4), are used to polymerise cyclic oxygen compounds and also occur in some other reactions.
Supported
Metal
Catalysts
A recent to patent to Dow Chemical Company (US Patent 4,367,167) describes the preparation of supported metallic catalysts by contacting a suitable support such as alumina with an aqueous solution of a compound of an active metal, especially a noble metal, and then with a solution of a reducing agent in a water-imniscible organic solvent, and drying under reduced pressure.
Crystalline Gallosilicate Catalyst Supports
Catalysts
and
British Petroleum Plc (Public Limited Company) have patented (GB 2,102, 779) a new catalvst comprisinq a mixture of oxides of formula: 0.9 t 0.25 M2/,,: Ga203: 1-6 Si02: zH 0 where n is the valency of M, Z = O-56 and M is a lanthanide or one of a number of other metals including Fe, Co, Ni and the noble metals. B.P. claim that it may be used per se for hydrocarbon crackingand hvdrzasina. toluene disoroPortion to xyiene, hydrocarbon reforming,' lSO' merisation and methanation; impregnated with active metal, it may be used,for example,to catalyse ethanol or hydrocarbon production from synthesis gas.
The Surface
State of Sn02s20,
Catalysts
N. Yamazoe, S. Tokushige, T. Kutose and T. Seiyama of Kyushu University Japan, have investigated the surface properties and states of Sn02-Sb 0 catalysts to determine the promo 2.4 ing effects of this catalyst system. (See sL##blysls-
Volume
7 No. 1
-July
1983
Nippon Kagaku Kaishi (1982) 1885). Temperature programmed desorption of oxygen from a series of the catalysts with varying Sb contents (x atomic %) showed that oxygen desorption increased with an increase in x, reaching a maximum at x = 30%. The same trend was also observed in the specific activity for the formation of acrylaldehyde in the pulse reaction of propene. These results indicate that the catalvst surface is favourably modified by the addition of Sb,0. to SnO-. While X-rav diffraction anflgsis de&ted Sb O4 only for x r 30%, XPS reveale 4 a surface enrichment of Sb which becomes most significant at x = 20 Q, 30%. The thickness of the Sb-enriched surface layer was estimated from SIMS experiments to be 20 fi or thinner. It is concluded that the active sites of the Sn02-Sb204 catalysts are provided by the Sb-enriched surface layer.
Synthesis of Gaseous Hydrocarbons from Syngas: the Selectivity of Iron-LamelTar Compounds on Graphite Catalysts E. Kikuchi, T. Ino and Y. Morita (Waseda University, Japan) have shown in previous work (J. Japan Petrol. Inst., 21 (1978) 242; J. Catal. 57 (1979) 27 and 62 (1980) 189) that iron, when supported on graphite, was catalytically. active in the production of Cp-C4 hydrocarbons with high selectivity'by'the hydrogenation of CO. E. Kikuchi, Y. Morita et al. (J. Japan Petr. Inst., 25 (1982) 360) have now investigated the reaction using a series of lamellar compounds of graphite (LCG) containing iron as the catalytically active component. After hydrogen reduction, the FeCl?-LCG exhibited catalytic activity for S'ynthesis of hydrocarbons, the distribution of which depended on the reduction conditions. With increasing temperature and time of reduction,the catalytic activity decreased and the hydrocarbon distribution shifted toward lower molecular weight products, probably due to a decrease in the thickness of the layer intercalated with the ferrous chloride, this layer acting as a spacer promoting the diffusion of reactants and products; The addition of manganese chloride to the iron-LCG catalyst was shown to be effective in changjng the hydrocarbon distribution to higher molecular weights and more olefin products. After hydrogen reduction of iron-manga-
Salt Catalysts
Catalysts in Chemistry (R.H. Chandler Ltd.) occasionally publishes translations of important Russian or other articles and reviews of particular topics. Vol. 13, No.4 (1983) contains a biblioqraohv (bv D. Evton) which contains-short summaries of'23 recent articles and patents in which the use of oxonium salts as catalysts is described. These salt&of general formula R3OX, especially salts such as triethvl oxonium tetrafluoroborate (Et30BF4), are used to polymerise cyclic oxygen compounds and also occur in some other reactions.
Supported
Metal
Catalysts
A recent to patent to Dow Chemical Company (US Patent 4,367,167) describes the preparation of supported metallic catalysts by contacting a suitable support such as alumina with an aqueous solution of a compound of an active metal, especially a noble metal, and then with a solution of a reducing agent in a water-imniscible organic solvent, and drying under reduced pressure.
Crystalline Gallosilicate Catalyst Supports
Catalysts
and
British Petroleum Plc (Public Limited Company) have patented (GB 2,102, 779) a new catalvst comprisinq a mixture of oxides of formula: 0.9 t 0.25 M2/,,: Ga203: 1-6 Si02: zH 0 where n is the valency of M, Z = O-56 and M is a lanthanide or one of a number of other metals including Fe, Co, Ni and the noble metals. B.P. claim that it may be used per se for hydrocarbon crackingand hvdrzasina. toluene disoroPortion to xyiene, hydrocarbon reforming,' lSO' merisation and methanation; impregnated with active metal, it may be used,for example,to catalyse ethanol or hydrocarbon production from synthesis gas.
The Surface
State of Sn02s20,
Catalysts
N. Yamazoe, S. Tokushige, T. Kutose and T. Seiyama of Kyushu University Japan, have investigated the surface properties and states of Sn02-Sb 0 catalysts to determine the promo 2.4 ing effects of this catalyst system. (See sL##blysls-
Volume
7 No. 1
-July
1983
Nippon Kagaku Kaishi (1982) 1885). Temperature programmed desorption of oxygen from a series of the catalysts with varying Sb contents (x atomic %) showed that oxygen desorption increased with an increase in x, reaching a maximum at x = 30%. The same trend was also observed in the specific activity for the formation of acrylaldehyde in the pulse reaction of propene. These results indicate that the catalvst surface is favourably modified by the addition of Sb,0. to SnO-. While X-rav diffraction anflgsis de&ted Sb O4 only for x r 30%, XPS reveale 4 a surface enrichment of Sb which becomes most significant at x = 20 Q, 30%. The thickness of the Sb-enriched surface layer was estimated from SIMS experiments to be 20 fi or thinner. It is concluded that the active sites of the Sn02-Sb204 catalysts are provided by the Sb-enriched surface layer.
Synthesis of Gaseous Hydrocarbons from Syngas: the Selectivity of Iron-LamelTar Compounds on Graphite Catalysts E. Kikuchi, T. Ino and Y. Morita (Waseda University, Japan) have shown in previous work (J. Japan Petrol. Inst., 21 (1978) 242; J. Catal. 57 (1979) 27 and 62 (1980) 189) that iron, when supported on graphite, was catalytically. active in the production of Cp-C4 hydrocarbons with high selectivity'by'the hydrogenation of CO. E. Kikuchi, Y. Morita et al. (J. Japan Petr. Inst., 25 (1982) 360) have now investigated the reaction using a series of lamellar compounds of graphite (LCG) containing iron as the catalytically active component. After hydrogen reduction, the FeCl?-LCG exhibited catalytic activity for S'ynthesis of hydrocarbons, the distribution of which depended on the reduction conditions. With increasing temperature and time of reduction,the catalytic activity decreased and the hydrocarbon distribution shifted toward lower molecular weight products, probably due to a decrease in the thickness of the layer intercalated with the ferrous chloride, this layer acting as a spacer promoting the diffusion of reactants and products; The addition of manganese chloride to the iron-LCG catalyst was shown to be effective in changjng the hydrocarbon distribution to higher molecular weights and more olefin products. After hydrogen reduction of iron-manga-