Catalytic combustion of toluene over the Ce-based composite oxides prepared by hard-template methods

Ce-based composite oxides (CeM-HT, M=Cu, Mn, Fe, and Co) were prepared by the hard-template method and characterized by XRD, O₂-TPD, nitrogen physisorption, and H₂-TPR; their catalytic performance in toluene combustion was investigated. The results show that CuO, MnO_x, FeO_x, and Co₃O₄ can be well dissolved into the CeO₂ lattice, forming Ce-O-Cu, Ce-O-Mn, Ce-O-Fe, and Ce-O-Co solid solutions, respectively. The CeO₂ lattice is significantly distorted by the incorporation of Cu and Mn ions, but less affected by the doping of Fe and Co ions. Moreover, a little amount of Co₃O₄ crystal exists in the CeCo-HT oxide catalyst. The Ce-based composite oxides exhibit excellent catalytic performance in toluene combustion; the toluene conversions over CeFe-HT, CeCo-HT, CeMn-HT, and CeCu-HT oxide catalysts reach 93.7% at 300 ℃, 95.0% at 270 ℃, 96.5% at 260 ℃, and 95.0% at 230 ℃, respectively. The catalytic activity of the Ce-based composite oxides is closely related to their oxygen desorption amount, oxygen storage capacity, and reducibility, following the order of CeCu-HT > CeMn-HT > CeCo-HT > CeFe-HT.