Two types of catalytic sites of In2O3-Co3O4/CeO2 and their synergy for highly selective CO2 hydrogenation to methanol

Abstract

The increasing concentration of greenhouse gases, specifically CO₂, requires innovative mitigation approaches. Catalytic CO₂ reduction shows potential for producing high-value-added products from CO₂, but the poor catalyst activity and product selectivity remain significant challenges. Oxygen vacancies and the interaction between the support and active components significantly influence the catalytic reactivity of a catalyst. Herein, we demonstrated a novel strategy to design highly efficient catalysts; namely, the reducibility of CeO₂ was exploited to tune the In₂O₃-Co₃O₄ catalyst for CO₂ hydrogenation, creating synergetic double-type active sites that the O_V1 oxygen defects (generated by hydrogen reduction) on CeO₂ surface as active sites for CO₂ adsorption and the In-Co-Ce interfaces as active sites for hydrogenation of the adsorbed CO₂ to methanol via formate intermediates. Consequently, an excellent methanol selectivity of 74 % was achieved for CO₂ hydrogenation, leading to a very high methanol space–time yield of 276.8 mg∙h⁻¹∙g_In-Co⁻¹ under mild reaction conditions (3 MPa, 280 °C, 2400 mL∙g_cat⁻¹∙h⁻¹), which is 4.8-fold higher than that without CeO₂. This study highlights the highly synergistic effects of two types of catalytic sites of the CeO₂ supported In₂O₃-Co₃O₄ catalyst and reveals a new pathway for designing new catalysts for more efficient CO₂ hydrogenation to methanol (CHTM)