Surface Acidity/Basicity and Oxygen Defects of Metal Oxide: Impacts on Catalytic Performances of CO2 Reforming and Hydrogenation Reactions

CO2 utilizations and conversions contribute to the reduction of greenhouse gas emissions and regeneration of industrial exhausts. Reforming and hydrogenation processes can transform CO2, hydrogen and hydrocarbons to syngas and other value-added products. To ensure a high activity, selectivity and stability as well as anti-coking property, efficient adsorption and activation of CO2 exert a profound impact. Among the catalysts adopted in these reactions, metal oxides have been proven active for adsorbing and activating CO2 based on surface acidity/basicity and oxygen defects. In this review, the impacts of these two physicochemical properties of metal oxides on the CO2 adsorption and activation will be comprehensively and systematically summarized in terms of three performance criteria (CO2 conversion-activity, product yield-selectivity, anti-coking property-stability) in two types of reactions relating to thermo-catalytic conversion of CO2 (reforming and hydrogenation). In addition to the critical discussion of the structure-performance relationships, the reaction/deactivation mechanisms and origin of surface acidity/basicity and oxygen defects are also introduced in depth. Finally, conclusive remarks of the main contents and proposed future works are provided.

Automated summary

CO2 utilizations and conversions play a significant role in reducing greenhouse gas emissions and regenerating industrial exhausts. Metal oxides, as catalysts, have been proven effective in adsorbing and activating CO2 based on surface acidity/basicity and oxygen defects. This review comprehensively summarizes the impacts of these physicochemical properties of metal oxides on CO2 adsorption and activation, with a focus on CO2 conversion activity, product yield selectivity, and catalyst stability in reforming and hydrogenation reactions. Additionally, the review explores the structure-performance relationships, reaction/deactivation mechanisms, and origins of surface acidity/basicity and oxygen defects.