Metal organic framework template method for the preparation of bimetallic oxide CunCoOx catalysts for the catalytic oxidation of volatile organic compounds

Abstract

A series of CunCoOx bimetallic oxides were synthesized by calcination of xCu/ZIF-67 precursors pre-impregnated with Cu2+. The Cu7CoOx catalyst demonstrated remarkable reactivity, reaching about 90 % conversion of toluene and ethylene at 194 °C and 162 °C. Additionally, Cu7CoOx was deemed suitable for applications at high space velocities, and also displaying superior stability. The physicochemical properties of CunCoOx were investigated by SEM, TEM, XRD, FTIR, BET, Raman, TG, O2-TPD, H2-TPR and XPS characterizations. The excellent catalytic performance of Cu7CoOx is attributed to the strong interaction of the two metal oxides, excellent redox ability, abundant lattice defects, more reactive oxygen species and higher concentrations of Co2+ and OLatt species. Density functional theory (DFT) calculation revealed CuO/Co3O4 (220) (Eads,O2 = −0.92 eV, Eads,toluene = −1.52 eV) displayed lower adsorption energy for toluene and oxygen molecules than Co3O4 (220) (Eads,O2 = −0.30 eV, Eads,toluene = −0.90 eV), which was favorable for the catalyst to catalyze the oxidation of VOCs. The possible degradation mechanism of toluene on Cu7CoOx was revealed using in situ DRIFTS. Thus, this work provides a non-noble metal catalyst with great application potential in VOCs treatment.