CuO_x‑V₂O₅–WO₃/TiO₂ Catalysts withTuned Redox–Acid Sites for Low-Temperature Chlorobenzene Oxidation

Abstract

Chlorobenzene (CB), as a representative chlorinated volatile organic compound (CVOC), is a persistent pollutant that demands efficient degradation strategies. A key challenge lies in simultaneously optimizing the catalyst redox capacity and surface acidity to enable C–Cl bond cleavage and Cl^– desorption. Herein, a series of CuO_x-modified V₂O₅–WO₃/TiO₂ (xCu-VWTi) catalysts were developed and evaluated for CB oxidation. The optimal 5%Cu-VWTi catalyst achieved 90% CB conversion at 250 °C and remained stable for over 60 h. Characterizations reveal that a low Cu loading (≤5%) can enhance the V⁵⁺/V⁴⁺ redox cycle and increase lattice oxygen mobility through doping. It also reduces the number of surface Lewis acid sites (LAS), which promotes the complete oxidation of CB to CO₂. Excessive Cu content (10%) causes the aggregation of CuO nanoparticles and alters the electronic structures of V and Ti. This results in a significant increase in the proportion of LAS, as indicated by the rise in the L/B ratio from 14.9 to 15.7, which subsequently reduces the catalytic activity. In situ DRIFTS experiments demonstrate that moderately dispersed Cu (≤5%) can balance Cl^– desorption and C–Cl bond activation through Cu–O–V interactions. However, Cu aggregation disrupts this synergistic effect. This study offers mechanistic insight and design guidance for redox–acid bifunctional catalysts toward efficient CVOC abatement.