Synthesis of gaseous hydrocarbons from carbon monoxide and hydrogen over transition metal catalyst (Part 6). The selectivity of iron-lamellar compound of graphite catalysts in Fischer-Tropsch synthesis.

Abstract

The hydrogenation of carbon monoxide was investigated using a series of lamellar compounds of graphite (LCG) containing iron as a catalytically active component. After hydrogen reduction, the FeCl3-LCG exhibited catalytic activity for synthesis of hydrocarbons, of which the distribution depended on the reduction conditions. With increasing reduction temperature and period, the catalytic activity decreased, and the hydrocarbon distribution shifted toward lower molecular weight products, probably, due to the decrease in the thickness of the layers intercalated with ferrous chloride, which acted as a spacer promoting the diffusion of reactants and products. The addition of manganese chloride to iron LCG catalyst was shown to be effective to change the hydrocarbon distribution to higher molecular weight and more olefinic products. After the hydrogen reduction of iron-manganese LCG catalyst at higher temperatures, the formation of higher molecular weight hydrocarbons (C5+) decreased, and the pattern of hydrocarbon distribution became relatively narrow. The results showed that the percentage of C2-C4 hydrocarbons slightly increased and was greater than the maximum yield predicted by the Schulz-Flory molecular weight distribution of hydrocarbon products in CO hydrogenation.