A CuMnO2 Based Copper-Manganese Catalyst for Low-Temperature CO Oxidation
Nikolai A. Sokovikov, Dmitry A. Svintsitskiy, Vera M. Metalnikova, Svetlana V. Cherepanova, А. И. Боронин
Abstract
Abstract Conditions for the preparation of the X-ray single-phase CuMnO2 mixed oxide with crednerite structure are studied. The catalytic performance of the obtained samples in the reaction of CO oxidation is tested depending on the synthesis temperature and the pH of the initial solution. Structural features, surface composition, metal states, and thermal stability of the copper-manganese mixed-oxide samples are studied by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetry (TGA) methods, respectively. It is established that the crednerite-type CuMnO2 mixed oxide samples are catalytically active at the temperatures exceeding 40 °C. The powder XRD and TGA data indicate that heating the copper-manganese catalyst in the CO+O2 reaction mixture up to 350 °C causes a phase transition leading to the formation of a CuyMn3–yO4 spinel-type phase characterized by the highest catalytic activity. The XPS data indicate that the formation of the spinel structure on the surface of active particles is accompanied by the appearance of a characteristic Cu 2p3/2 peak with a binding energy of ~930.7 eV. The revealed structure–activity correlation shows that the crednerite-type CuMnO2 species can act as a precursor for the preparation of a highly efficient copper-manganese catalyst for the low-temperature CO oxidation.