Influence of LaCoO3 perovskite oxides prepared by different method on the catalytic combustion of ethyl acetate in the presence of NO

Effect of preparation methods, including selective etching (LCO-E), sol–gel (LCO-S) and co-precipitation (LCO-C), on the physicochemical properties of LaCoO3 and its catalytic activity for removal ethyl acetate (EA) are investigated. The physicochemical properties of these LaCoO3 materials are characterized by XRD, N2 physicosorption, SEM, HR-TEM, H2-TPR O2-TPD, EPR and in situ DRIFTS. The preparation methods have a strong influence for LaCoO3 perovskites on crystalline size, surface area, redox ability, oxygen mobility, Co3+ content and the catalytic activity from the highest to the lowest value were LCO-E > LCO-S > LCO-C. In particular, we found that NO plays different roles in the reaction depending on the reaction temperature below or above 160 ℃, where the oxidation of NO to NO2 occurs or not. This directs a new strategy to simultaneously remove EA and NO, and even to pollutants with more complicated compositions. Moreover, it is found that the presence of small amount of water can significantly improve the reaction activity. The presence of excess water severely occupies the active sites, resulting in the decrease of activity. A mechanism for the removal of NO and EA in the presence of water is proposed.