Plasma-catalytic CO₂ hydrogenation over Cu-ZnO/Al₂O₃ foam ceramic catalysts

CO₂ hydrogenation using plasma catalysis is a promising approach for CO₂ conversion and utilization under mild conditions. In this study, a parallel-plate dielectric barrier discharge (DBD) reactor packed with Cu-ZnO/Al₂O₃ foam ceramic catalysts (CZAxy, where xy denotes the CuO-to-ZnO mass ratio x:y) was developed for plasma-catalytic CO₂ hydrogenation. The results demonstrate that the incorporation of ZnO in the CZAxy catalysts created a synergistic interaction at the Cu-ZnO interface. An optimal CuO-to-ZnO mass ratio of 2:1 was identified in the CZA21 catalyst, which exhibited the highest specific surface area, the strongest Cu-ZnO interaction, and the greatest CO₂ adsorption capacity. These enhanced catalyst properties contributed to improved gas conversion, with the highest CO₂ and H₂ conversions reaching 22.4% and 15.5%, respectively, using the CZA21 catalyst. The presence of the CZAxy catalysts suppressed the formation of CO while promoting the generation of liquid products, particularly alcohols such as methanol and ethanol. The CZA21 catalyst achieved the highest selectivities for methanol (20.9%) and ethanol (3.6%), while the selectivity of the primary gaseous product, CO, was reduced to 68.5%. The CZAxy catalysts demonstrated high stability during the reaction and enhanced energy yields for both gas conversion and product generation, with the CZA21 catalyst exhibiting the best performance.