Low temperature catalytic oxidation of propane over cobalt-cerium spinel oxides catalysts

摘要

In this study, the cobalt-cerium spinel oxides catalysts were prepared via a citric acid complex method. The catalytic performance and physicochemical properties of the samples for deep propane oxidation were evaluated. Co2Ce1Ox catalysts exhibit the superior low temperature activity with a T-50 value of 220 degrees C, which is much lower than both individual cobalt and cerium oxides. The results show that cerium ions could enter into the spinel-type lattice of the cobalt oxides and lead to the severe lattice distortion. The activated Co-O bonds favor the propane activation and enhance the reducibility of active Co3+ species. Meanwhile, high proportion of Co3+ content and better oxygen mobility are also observed in the cobalt-cerium spinel oxides catalysts. The kinetic and the transient experiments reveal that the reduction step of the catalysts plays a crucial role in the deep catalytic propane oxidation. The reaction rate of Co2Ce1Ox catalyst reaches 0.22 mu mol g(-1) s(-1) at 200 degrees C and its activation energy is the lowest (57.9 kJ mol(-1)). All the results indicate that the combination of redox behaviors of Co3O4 and oxygen vacancies of CeO2 offer useful support for catalysts design toward propane oxidation at low temperature.