Reversal of Selectivity to CO in CO2 Hydrogenation by Forming an InCo Alloy and H-ZSM-5 Zeolite-Driven Suppression of Cobalt Oxidation Deactivation in CO2 Methanation Reaction

Developing efficient and stable catalysts to convert CO2 to desirable C1 products is of great importance for carbon resource utilization. Cobalt-based catalysts usually show high activity in methanation but poor selectivity to CO from the reverse water-gas shift (RWGS) reaction. Herein, we synthesized In-doped CeO2-supported cobalt catalysts for RWGS reaction, which achieved almost reverse 100% selectivity toward CO with a near-equilibrium CO2 conversion of about 49% at 500 °C and 1 MPa. Results showed that catalyst reduction could result in In species migration onto Co particles to form an InCo alloy, thereby modulating the cobalt electronic structure. It thus strengthened Co–H* bonding but weakened CO adsorption and activation, in turn inhibiting CH4 formation via HCOO* and CO hydrogenation. Interestingly, the reaction temperature-dependent deactivation was observed over 10Co/CeO2, owing to cobalt oxidation determined by the O atom chemical potential (μO). Theoretical investigations demonstrate that μO is related to the free energy of H2O and H2 (μO = GH2O‐GH2), where the reaction temperature exhibits different degrees of effect on GH2OandGH2. Based on the deactivation behavior study, we successfully developed a simple strategy to suppress oxidation deactivation by mixing with hydrophilic H-ZSM-5 zeolite to drive H2O desorption away from the cobalt surface during the CO2 methanation reaction with much more H2O molecules produced.