Catalytic oxidation of chlorobenzene over Cr-Ce-O catalysts modified by transition metals

Chlorobenzene was applied as a probe for chlorinated volatile organic compounds, and rare-earth based CeO2 was used as the active oxide. The Cr-Ce-O catalysts were prepared by complexation method with citric acid adding. The effects of the molar ratio of Cr/Ce, the doping and amount of transition metal oxide, the supports, and calcination temperature on chlorobenzene oxidation were investigated. The as-prepared catalysts were characterized by XRD, BET, SEM, H2-TPR and XPS. CrCeOx solid solution was formed between Cr2O3 and CeO2, and the specific surface area of Cr2O3-CeO2/Al2O3 catalyst with ZrO2 doping was improved, significantly. The supports exhibited an important influence on the morphology and structure of the active components. The oxidation activity of these catalysts with calcination temperature at 400°C and cordierite support was higher. The results also exhibited that the ZrO2 doping also displayed a significant effect on the oxidation activity. When the molar ratio of Zr/Cr was 1:2, the Cr2O3-CeO2-ZrO2/cordierite catalyst showed the highest performance, and the conversion rate of chlorobenzene oxidation was 92.7% (the reaction temperature was 350°C). It was mainly attributed to ZrO2 doping promoted the interaction between CeO2 and Ce2O3, Cr2O3 and ZrO2, and enhanced oxygen vacancy attributed to the increase of surface-active oxygen (Osur). © 2021, Editorial Board of China Environmental Science. All right reserved.