Inhibiting water-gas-shift reaction in the Fischer–Tropsch synthesis: Unraveling the roles of phase and facet over iron carbides

An effective method, regulating the phase and facet of FexCy catalysts, is proposed in this study to adjust the catalytic performance of WGSR/FTS and thus affect CO2 selectivity in the FTS reaction. The role of phase and facet over FexCy catalysts in regulating the reaction mechanisms and catalytic activity of WGSR/FTS in the FTS reaction are clearly unraveled. The results conclude that the local electronic environment of Fe atoms and the position of d-band center arisen from the phase and facet difference of FexCy play the determined role in the regulation of catalytic activity of WGSR/FTS over different FexCy catalysts. Among them, χ-Fe5C2(5 1 0) facet is screened out as the optimal catalyst to effectively inhibit CO2 formation and to present excellent FTS activity under the FTS conditions. This study gives out a theoretical guide for the design of FexCy catalysts with the specific phase and facet to regulate the activity of FTS and WGSR and therefore greatly decrease CO2 selectivity in the FTS reaction.