✍ Scribed by Hui Ming; Bruce G. Baker
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The effect of preparation conditions on cobalt-silica gel catalysts has been investigated by temperature-programmed reduction, differential thermal analysis, X-ray photoelectron spectroscopy, and magnetic susceptibility measurements. The results have been correlated with the performance of the catalysts for the conversion of syngas. It has been found that active Fischer-Tropsch (F-T) cobalt catalysts can be partially or totally reduced to the metal phase during activation. However, reducibility of the catalysts is a necessary but not sufficient characteristic in ensuring good activity. The pH of the impregnating solution influences surface charge and solubility of silica gel. Consequently, the physical and chemical properties of the cobalt species on the surface of silica gel are strongly affected by this parameter. At pH < 5 cobalt deposits as a cation. At pH < 2 the silica surface is positively charged so that the dispersion of cobalt and consequently catalytic activity are poor. At pH >/5, cobalt reacts to form silicates or hydrosilicates which are irreducible. Active catalysts are shown to adsorb hydrogen by spillover on to the silica support.
📜 SIMILAR VOLUMES
ZSM-5, ZSM-1 I, ZSM-12 and ZSM-34 were examined as supports for cobalt bifunctional Fischer-Tropsch catalysts in order to determine the influence of zeolite pore structure on the synthesis. All supports produced reasonably active catalysts, with activity increasing with the channel size of the zeoli
Natural gas and coal are converted to fuels by the Fischer-Tropsch reaction, i.e., by reacting CO with H 2 , the currently accepted mechanism involving surface carbide formation. We have monitored the adsorbed species and their evolution during Fischer-Tropsch reaction on the commercial catalyst Pt,