Sol-Gel Preparation of Perovskite Oxides Using Ethylene Glycol and Alcohol Mixture as Complexant and Its Catalytic Performances for CO Oxidation

摘要

We reported an updated sol-gel method for the preparation of perovskite oxide using ethylene glycol and alcohol mixture as complexant. Relative to that prepared by sol-gel method using citric acid as complexant, the sample prepared by this updated method showed porous structure, higher surface area, more oxygen vacancies and stronger reducibility, due to a two-step combustion process. By comparing the phase transformation temperature of perovskite oxides using different transition metals, it was inferred that the electron distribution in the 3d orbit is a crucial factor influencing the formation of perovskite structure. The easier the electrons to be excited, the easier the perovskite structure to be formed. Catalytic results showed that the sample (e. g., LaCoO3-EM) prepared by the updated method is more active for CO oxidation than that prepared by citric acid method, with full CO conversion obtained at 135°C and no activity loss is observable either by long-term (30 h) or by cycling (3 times) stability tests. Effect of the chain length of alcohols on the properties of LaCoO3 was also studied.