Study by Mossbauer spectroscopy and magnetization measurement of the evolution of iron catalysts used in the disproportionation of CO

Mossbauer spectroscopy and magnetization measurement have been used to investigate the chemical state of a supported iron catalyst during the disproportionation of carbon monoxide. It was observed that the Fe2O3 precursor was reduced to alpha Fe metal during the initial pretreatment under H-2 and that this metal catalyzed the decomposition of CO. At 808 K and under the reaction conditions used the catalyst was carburized directly into Fe3C until no other iron phase could be identified. ?his carburization was correlated to the decrease of reaction rate and seemed to be the process of catalytic poisoning. Under experimental conditions, no other carbides were observed during reaction time. (C) 1997 Elsevier Science Ltd.