Effects of deep eutectic solvent on Cu-Mn-C-O composite catalysts: Surface species, physical and chemical properties in methane combustion

Abstract

A series of Cu-Mn-C-O composite catalysts for low-temperature catalytic combustion of methane were successfully prepared by synthetic induction of CuMn2O4 precursors via hydrothermal method which used deep eutectic solvent (DES) as an inducer. The structure and properties of the catalyst were investigated by XRD, BET, XPS and SEM characterizations to investigate the effect of DES addition on the crystal growth of the catalyst. The results showed that the Cu-Mn-C-O composite catalyst produced a new phase of MnCO3, which changed the number and distribution of acid-base sites on the catalyst surface and effectively promoted the desorption of catalytic reaction products. The catalytic activity test showed that the methane catalytic activity of the Cu-Mn-C-O composite catalyst was significantly enhanced at Mn/C molar ratio of 1:2.5, with T50 and T90 values of 365 °C and 425 °C, respectively. This can be attributed to the high proportional distribution of high-valent manganese in the internal electronic structure of the composite catalyst system, which generated a large number of surface adsorbed oxygen species and thus facilitated the oxidation of methane at lower temperatures. Thermal analysis of composite catalysts revealed relatively high activation energy and thermal stability in the combustion process of composite catalysts. This study will lead to innovative insights into the design of composite catalysts for methane oxidation.