Effect of Cr doping in promoting the catalytic oxidation of dichloromethane (CH2Cl2) over Cr-Co@Z catalysts.

A core-shell catalyst which consists of a Co3O4 core and ZSM-5 shell, was prepared by microwave hydrothermal method and subjected for dichloromethane (DCM) oxidation. Chromium, cerium, niobium, and manganese species were separately introduced into the core-shell catalyst using the wet precipitation method and denoted as M-Co@Z (M = Cr, Ce, Nb, Mn). The catalytic activity of the Cr-Co@Z catalyst was significantly increased due to the interaction between Cr2O3 and Co3O4. The results of Raman spectra indicated the incorporation of chromium into the Co3O4 lattice and revealed the existence of the interaction between Cr2O3 and Co3O4. The synergistic effect between Cr2O3 and Co3O4 might be conducive to the generation of highly defective structure and increase the ratio of Co3+/Co2+ of the sample, leading to its better oxygen mobility. The dechlorination ability of Cr-Co@Z was also promoted due to the enhanced mobility of lattice oxygen. Based on in situ DRIFT studies, a possible reaction route of CH2Cl2 oxidation over Cr-Co@Z catalyst was proposed.