Ultrathin 3D CoMn nanoflowers coupled diatomite for highly efficient catalytic oxidation of CO and propane

Abstract

Manganese oxides are promising catalysts for the treatment of VOC gas pollutants due to variable valences and abundant oxygen vacancies. The surface properties of manganese oxides significantly affect their catalytic activity. Thus, the development of appropriate modulation strategies for manganese oxides is of great significance. Herein, ultrathin (1–2 nm) three-dimensional (3D) CoMn nanoflowers have been in-situ planted on the surface of a naturally abundant resource – diatomite. Due to the open diffusion channels of diatomite and 3D coordination of CoMn nanoparticles, more open space and exposed sites are created for the transport and migration of O2, CO and propane. Compared to the pure CoMn, the obtained cobalt-manganese/diatomite (CoMn/Dia) composite contains more surface defect sites and oxygen vacancies, resulting in 90 % of carbon monoxide (CO) and propane (C3H8) conversion at as low as 108 °C and 250 °C, respectively. Density functional theory (DFT) results demonstrate that the doping of Co elements and the ultrathin structure of CoMn nanoflowers induce the formation of oxygen vacancies and weaken the Mn-O-Co bond in CoMn/Dia composites, which significantly accelerate the oxygen cycling during the oxidation reactions of CO and propane. In addition, the prepared CoMn/Dia catalyst exhibits excellent stability with consistent catalytic efficiency achieved for 70 h. Due to the simple synthesis method and lower cost raw materials, this research provides new insight into the scale-up production of efficient and economical Mn-based catalysts.