Manipulation of Mn/Ce ratio for deep chlorobenzene oxidation: Catalytic mechanisms and byproducts analysis

Abstract

In this research, a sequence of spatial porous MnCeOx catalysts with varying Mn/Ce from 3:1 to 1:7 were synthesized using the sol–gel method for chlorobenzene (CB) oxidation. Mn1Ce1 exhibited the best performance due to its high lattice oxygen content and the strong interaction between Ce and Mn. The increase in Mn content in CeO2 catalysts resulted in enhanced redox properties and acidity, which was beneficial for the adsorption and activation of CB, thus enhancing the selectivity and the desorption of HCl on the catalyst surface. Carbon deposition and the formation of metal chloride were the main reasons for catalyst deactivation. At low temperature regions (150 ∼ 300 °C), insufficient oxidation capability and the chlorine deposition on the catalyst surface resulted in the formation of various chlorinated compounds. As the temperature increases (300 ∼ 450 °C), the release of HCl and more reactive oxygen species is available on the catalytic interface, generating various oxygen-containing degradation intermediates. This work proposed a fine-designed, low-cost mixed metal oxide catalysts for low temperature CB oxidation, and provided novel in-depth understandings of degradation intermediate formation thermodynamics. Our findings would be helpful for deep purification of chlorinated VOCs polluted industrial tail gas.