Active phase of iron catalyst for alcohol formation in hydrogenation of carbon oxides

Abstract

Hydrogenation of CO2 over iron catalysts has been carried out and compared with the activity obtained with CO. The rates of hydrocarbon and alcohol formation were higher in the reaction with CO. The rates of hydrocarbon and alcohol formation were suppressed by addition of steam to the reactant gas mixture of H2–COx. Although no significant change in the structure of the catalyst was observed by the X-ray diffraction analyses, change in the oxidation state of the surface iron was detected by recording X-ray photoelectron spectroscopy of the catalysts. During the reaction with CO, the catalyst surface was further reduced even after the reduction at 500 °C, whereas it was oxidized in the reaction with CO2. A change in product distribution and the results of X-ray photoelectron spectroscopy analyses showed that the iron carbide is the active site for hydrocarbon formation and the oxygen species in iron hydroxide (OFeOH) may be relevant to the formation of MeOH. Copyright © 2000 John Wiley & Sons, Ltd.