Elucidating the nature role of acid etching on the CoMnOx catalyst with outstanding performance for the catalytic combustion of o-dichlorobenzene

Abstract

Enhancing chlorine and water resistance and suppressing by-product generation are crucial issues in the catalytic degradation of CVOCs. In this paper, surface acid modified (sulfurized and phosphorized) CoMnOx rhombic dodecahedra catalysts were synthesized for the deep destruction of o-Dichloroethane (o-DCB), considering its better reducibility, abundant acid sites, excellent mass transfer and higher specific surface area. The strong interaction between Co and Mn in the acid-modified CoMnOx stimulated the efficient production of active Co3+, Mn4+ and oxygen species, which considerably promoted C-H bond and C-Cl bond cleavage. Acid etching also creates a rich surface defect structure that promotes the exposure of more reactive sites and facilitates the adsorption of reactant molecules. Furthermore, we found that the acid sites of the prepared CoMnOx-TAA materials effectively inhibited by-product formation and were highly selective for HCl. TPSR analysis gave the distribution of the reaction products and further confirmed that the final products were CO2 and HCl. More importantly, CoMnOx-TAA exhibited excellent water and chloride resistance. Moreover, EPR characterization confirmed a significant increase in the number of oxygen vacancies on the catalyst surface after acid modification of CoMnOx. TPD indicated that the modified catalyst possessed abundant weak and medium acid sites. The formation pathway and reaction mechanism of oxidative decomposition were also studied by in-situ FTIR and DFT calculations. This work provides promising candidates and new insights into the industrial catalytic degradation of o-DCB.