Catalytic combustion of toluene over CeO2–CoOx composite aerogels†
A rational approach for the optimization of cobalt based catalysts suitable for VOC combustion is to modulate the pore structure and increase the dispersion of active species. In this study, we have prepared CeO2–CoOx composite aerogels with a continuous porous structure using an epoxide-initiated gelation process and evaluated them in the catalytic combustion of toluene. The influence of the Ce/Co ratio on the structural properties and catalytic activities of the CeO2–CoOx aerogels was investigated using various characterization methods. The surface area of the CeO2–CoOx aerogels showed a volcanic curve versus the Ce content. A higher specific surface area of 172 m2 g−1 was observed for the CeO2–CoOx-10 catalyst with a Ce/Co ratio of 1/10. In addition, the presence of Ce modified the redox properties and the surface chemical states of the CeO2–CoOx aerogels, such as the surface Co3+/Co2+ ratios, and surface absorbed oxygen species (O− and O2−), which played key roles in their catalytic activity. In comparison with different cobalt-based catalysts for toluene oxidation in the previous literature studies, the CeO2–CoOx-10 catalyst in this work exhibited better catalytic performance, reaching an optimal toluene conversion of 90% at 248 °C as well as the highest stability during the durability test under different temperature stages.