CATALYTIC BEHAVIOR AND PHASE-COMPOSITION CHANGE OF IRON CATALYST IN HYDROGENATION OF CARBON-DIOXIDE

Hydrogenation of C02 was conducted on iron catalyst under various reaction conditions to explore the catalytic behavior and the change of bulk phase composition. It was found by the use of Mossbauer spectroscopy that the metallic iron phase was transformed to a mixture of magnetite and carbides progressively during the course of reaction. The formation of Fe304 phase became more favorable under conditions which led to a high H20 partial pressure on the catalyst bed. On the other hand, the carburization of iron catalyst was enhanced at higher temperature, with ^-Fe5C2 phase being predominant over 0~Fe3C phase. Due to the fact that H20 produced in the Fischer-Tropsch reaction also contributes to the equilibrium of the reverse water-gas shift reaction, the common product H20 of these two steps plays a major role in suppression of overall C02 conversion level. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.