Deep insight into the catalytic removal mechanism of a multi-active center catalyst for chlorobenzene: an experiment and density functional theory study

Abstract

Catalytic oxidation is a promising dioxin purification removal technique due to high efficiency and low consumption, as well as no secondary pollution. In this work, a multi-active center catalytic system was prepared, and the catalytic removal of chlorobenzene (CB) was investigated. The results showed excellent CB conversion and CO₂ selectivity, especially the Pd_0.12V₄/TiO₂ catalyst with the lowest T₉₀ (256.6 °C) and activation energy (E_a) (8.29 kJ mol⁻¹). XRD, TEM, XPS, H₂-TPR, in situ DRIFT, and DFT analysis were carried out to examine the CB catalytic removal mechanism. The obtained data revealed that all components (PdO_x, VO_x and TiO₂) of the catalyst play an indispensable role in CB oxidation removal, and the redox cycle (2V⁴⁺ (Ti³⁺) + Pd²⁺ ↔ 2V⁵⁺ (Ti⁴⁺) + Pd⁰) was attributed to its superior CB catalytic performance. Additionally, a possible catalytic removal transformation mechanism of CB by the Pd_0.12V₄/TiO₂ catalyst was proposed, which was consistent with the experimental and in situ DRIFT spectroscopy results.