Reactivity and Preparation of Perovskite-Type Mixed Oxides LaBO3(B = Mn, Fe, Co) by Citrate Sol-Gel Method

摘要

Perovskite-type mixed oxides LaBO3(B = Mn, Fe, Co) were prepared by citrate sol-gel method in air(850?é, 24h). The oxygen stoichiometries and structures of these oxides were determined by XRD and TPR results as followings; LaMnO3.16(a = 5.507, c = 13.329 ?ê, hexagonal), LaFeO3.17(a = 5.554, b = 5.555, c = 7.863 ?ê, orthorhomibic), LaCoO3.0(a = 5.436, c = 13.095 ?ê, hexagonal). The temperature programmed reduction(TPR) experiments in static 300 torr H2 atmosphere shows that the reduction reaction of LaBO3(B = Mn, Fe, Co) proceeds into two stages, and thermal stabilities of these oxides decreased in the order of LaMnO3 > LaFeO3 > LaCoO3. According to the kinetic analysis the lowest activation energy was obtained for LaCoO3.