Reversal of Selectivity to CO in CO ₂ Hydrogenation by Forming an InCo Alloy and H-ZSM-5 Zeolite-Driven Suppression of Cobalt Oxidation Deactivation in CO ₂ 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.