Catalytic combustion of toluene over CeO2–CoOx composite aerogels

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