Investigation into the roles of interfacial H2O structure in catalytic oxidation of HCHO and CO over CuMnO2 catalysts

Abstract

The rapid deactivation of cost-effective MnO₂-based catalysts in humid air limits their application in practice, and the identification of the role of water in an oxidation process is significant for developing water-resistant MnO₂-based catalysts. Here, CuMnO₂ showed a 20.3% HCHO conversion in 10 hr at room temperature in humid air with relative humidity of 40%, but deactivated in 3 hr in dry air. The excellent activity and stability of HCHO oxidation in humid air were attributed to the positive effect of H₂O on HCHO oxidation to the H₂O-HOCH₂OH supermolecule assemblies via hydrogen bonds formed on CuMnO₂. H₂O-HOCH₂OH supermolecule assemblies tend to be oxidized to carbonate, which is further oxidized to CO₂. Furthermore, CuMnO₂ exhibited a much poorer activity of CO oxidation in humid air, but the CO conversion was still 100% in 10 hr in dry air. H₂O showed a competitive adsorption effect to CO on CuMnO₂. CuMnO₂ could be applied in HCHO elimination in humid air and CO elimination in dry air.