Abstracts 85. Catalytic gasification of graphite by tungsten, rhenium and tungstewrhenium R. T. K. Baker, J. J. Chludzinski, Jr., N. C. Dispenziere and L. L. Murrell (Corporate Research Science Laboratories, Exxon Research and Engineering Company, P.O. Box 45, Linden, NJ 07036, U.S. A.). Controlled atmosphere electron microscopy examinations have shown that both tungsten and rhenium are active catalysts for the graphite-oxygen reaction, although the former exhibits only marginal activity. Of the two materials, only rhenium is effective in catalyzing the gasification of graphite in hydrogen. From a comparison of the bicomponent system with that of its pure constituents, it is concluded that in oxygen, rhenium segregates to the surface, whereas in a reducing environment the surface is enriched with tungsten. Moreover, it was found that the intrinsic catalytic channeling rate of the mixed system is significantly faster than that of tungsten or rhenium in the graphite-oxygen reaction. 86. Inhibition of the platinum catalyzed gasification of graphite R. T. K. Baker and C. R. F. Lund (Corporate Research Science Laboratories, Exxon Research and Engineering Company, P.O. Box 4.5, Linden, NJ 07036, U.S.A.). J. A. Dumesic (IJniversity of Wisc0.r sin, Chemicul Engineering Department, Madison, WI 53706, U.S.A.). The effect of chlorine addition upon the oxyygen and hydrogen gasification of graphite has been examined using controlled atmosphere electron microscopy. When chlorine is added to the oxygen feed in the form of carbon tetrachloride the channeling of platinum catalyst particles ceases; when the poison is removed from the feed, the catalyst resumes channeling at a reduced rate. When the chlorine is added to the hydrogen feed channeling also ceases. However, in this case simply removing the poison from the feed does not restore activity. An intermittent oxygen treatment of the deactivated specimen is effective in restoring catalytic channeling. 87. Catalytic activity of a miscellaneous catalyst in water vapour gasification of carbon J. Adler, K. J. Hiittinger and R. Minges (Institut fiir Chemische Technik der Universitiit, 7500 Karlsruhe, FRG). Iron was shown to be the most relevant technical catalyst for pressure gasification of carbons with hydrogen. In water vapour gasification of carbons the catalytic activity of iron is strongly diminished by sulfur and especially increasing pressure. To overcome these problems investigations with catalyst mixtures of Fe and K were performed using various types of carbons. The miscellaneous catalyst dos not show the problems of pure iron as a catalyst and is even more active than pure potassium as a catalyst. 88. The stability of intermediate surface complexes in water vapour gasification of carbon without and with catalyst G. Hermann and K. J. Hiittinger (Znstitut fiir
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Chemische technik der Universitiit, KaiserstraJe 12, 7500 Karlsruhe, FRG). Desorption studies at linear temperature increase were performed with model carbons of various pretreatment temperatures, without and with catalyst, after gasification under different conditions followed by rapid cooling down. It was found, that the amount and the stability of carbon oxygen surface complexes depends on the pretreatment temperature of the carbon. In the presence of an iron metal as a catalyst desorption temperature is lowered and nearly independent of the pretreatment temperature of the carbon. After gasification in reducing atmosphere the desorption of aliphatic bound hydrogen was observed at about 6OO”C, whereas desorption of aromatic bound hydrogen occurs at about 1000°C. 89. Deactivation of finely dispersed nickel during gasification of activated carbon, studied by X-ray photoelectron spectroscopy (XPS) Teus Wigmans, Joeg Van Doorn and Jacob A. Moulijn (Institute,for Chemical Technology, Plantage Muidergracht 30 1018 TV Amsterdam, The Nether/and.s). In this study, it will be shown that the quantitative interpretation of XPS intensity ratios of nickel/carbon, carbon bonded oxygen/carbon and nickel bonded oxygen/nickel, of absolute XPS carbon intensities and of XPS binding energy patterns of Ni(2p3!*) and O(ls) electrons reveal insight in phenomena, that occur during heat treatment and gasification of finely dispersed nickel containing activated carbon. Decomposition of the catalyst precursor, reduction of the metal oxide, sintering of the metal and reoxidation during the gasification process appear to determine the catalytic action of nickel in gasification reactions of carbon in steam and hydrogen. 90. Catalytic gasification of chars J. L. Figueiredo, J. J. M. t)rfio, M. C. A. Ferraz and C. A. Bernard0 (Faculdade de Engenharia, Porto, Portugal). Pure and cobalt doped chars were prepared by carbonisation of sawdust and activated by gasification with carbon dioxide. The kinetics of gasification and the texture of the carbons obtained are quite different. The results are explained by the catalytic action of the metal, promoting the development of meso and macroporosity. 91. Catalytic carbons as catalysts for methanation and Fischer-Tropscb synthesis M. Audier. B. Bass, M. Coulon and L. Bonnetain (Ecole Nationale Supirieure D’Electrochimie et D’Electrometallurgie, Largs, Enseeg, BP 7.5-38402, Saint Martin D ‘Heres, France ). CO disproportionation on alloys of iron, cobalt and nickel produces carbon-supported true alloys catalysts owing to the phenomenon of fragmentation. They present an interesting activity and a great stability for the catalysis of the CO + Hz reactions. Their select-