Tuning the oxygen storage capacity and oxygen release properties of CeO₂-based catalysts for catalytic combustion of toluene

CeO₂ with varied doping transition metal was investigated to understand the oxygen storage capacity and oxygen release property of CeO₂-based catalysts for toluene combustion. The order of catalytic activity was as follows: CuCeO_x ≈ CoCeO_x > MnCeO_x > FeCeO_x > NiCeO_x > ZrCeO_x > CeO₂. Kinetic studies showed that the reaction on CuCeO_x proceed via an MvK mechanism and the oxygen of catalyst was crucial factor for the toluene combustion. H₂-TPR and XPS showed the addition of transition metal to CeO₂ could modify the surface lattice oxygen. Moreover, the oxygen storage capacity and oxygen release properties showed the transition metal additive not only change the amount of oxygen, but also affect the oxygen mobility. A linear relationship was observed between the catalytic activity and oxygen storage capacity. Diffuse reflectance infrared fourier transform spectroscopy showed the toluene first adsorbed on the surface of catalyst, and then reacted with oxygen of catalyst to form benzyl, benzoate and benzyl carbonate species. All these results provided a new strategy to develop high performance catalyst.