Unveiling the mechanism of alkali etched CuMn2O4-δ spinel catalysis enhance for acetone catalytic Oxidation: The roles of Metal-Oxygen bond and oxygen defect site

Abstract

Spinel is a powerful non-precious metal oxide catalyst that can be used to catalyze the combustion of volatile organic pollutants, potentially replacing precious metal catalysts. To enhance the catalytic activity and stability of CuMn2O4, we constructed gradient distribution of oxygen vacancies (Vo) on the CuMn2O4-δ surface utilizing alkali treatment method. Alkali treatment dissolves some of the Cu atoms of the CuMn2O4 catalyst, leading to the transformation of part of the Mn-O-Cu structure into the Mn-O structure, which was results in the lengthening of the Mn-O bond and the production of cation defects. The Mn-O bond breaks, releasing a large amount of reactive oxygen and forming oxygen vacancies. Highly reactive lattice oxygen and cation defects is more likely to participate in oxidation reactions. In the catalytic combustion of acetone, the alkali-treated catalyst showed high activity and stability, and the oxidation rate of acetone at 170 °C was increased by 2.86 times. Particularly, the alkali treatment catalysts can convert acetone that has been adsorbed into acetic acid and formic acid using catalyst lattice oxygen in anoxic environment. In the presence of an oxygen stream, the acetic and formic acids underwent direct oxidation, resulting in the formation of water and carbon dioxide. This work promotes the development of oxygen vacancy engineering on the surface of transition metal oxides and provides a new approach to improve the activity and stability of CuMn2O4 in real environments.