CARBIDE PHASES ON IRON-BASED FISCHER-TROPSCH SYNTHESIS CATALYSTS .1. CHARACTERIZATION STUDIES

The characterization of iron carbide phases formed on iron-based Fischer-Tropsch catalysts is reviewed in this part with particular emphasis on Mössbauer and XPS studies of selected iron and supported iron catalysts, in combination with some specific results in activity and selectivity. Mössbauer studies have shown clearly the evolution of bulk carbide species on iron catalysts under synthesis reaction conditions; the relationship of these to the nature of near-surface species and their temporal evolution under synthesis conditions is indicated by XPS results. Comparisons among reduced, unreduced and carbided iron catalysts are given; XPS and reaction results suggest that Fe3O4 is active for synthesis even in the absence of carbide phases. © 1991 J.C. Baltzer A.G., Scientific Publishing Company.