Catalytic oxidation of chlorobenzene and PCDD/Fs over V2O5-WO3/TiO2: insights into the component effect and reaction mechanism.

ABSTRACT

In this work, titania supported catalysts (V-W/Ti) with different vanadium-tungsten contents were prepared and evaluated in the catalytic oxidation of chlorobenzene, which was used as the model compound of dioxins. The results showed that V2O5 is the main active component for chlorobenzene oxidation, and doping of WO3 affects the valence distributions of vanadium, contributing a bimetallic synergistic effect. The catalysts were investigated by XRD, SEM-EDS mapping, Raman, and XPS, and the changes in V element valence state and chlorine content on fresh and used catalysts were observed by XPS. Moreover, in situ FTIR studies and chlorine balance were also conducted, the addition of WO3 is helpful to the breakage of C-Cl, and a reaction mechanism for the catalytic oxidation of chlorobenzene was proposed. 3 V-5 W/Ti catalyst with better catalytic activity was selected for catalytic oxidation of PCDD/Fs using a lab scale PCDD/Fs generating and decomposing system. The degradation efficiency was 66.5% at 200 °C and 62.2% at 300 °C, which indicated that the low reaction temperature of 200 °C was conducive to the catalytic degradation of PCDDs, while the high temperature of 300 °C was facilitated the degradation of PCDFs.