Effects of the preparation method on the simultaneous catalytic oxidation performances of LaCoO3 perovskites for NO and Hg0

Abstract LaCoO3 perovskites prepared by the molten-salt method (LaCoO3-M), the sol–gel method (LaCoO3-S), and the co-precipitation (LaCoO3-C) method were systematically characterized and its simultaneous oxidation abilities for NO and Hg0 in flue gas were investigated. Although the LaCoO3 perovskites were prepared successfully by the three different preparation methods, the simultaneous oxidation abilities for NO and Hg0 were of great difference. The preparation methods had a strong influence for LaCoO3 perovskites on surface area, Co3+ content, adsorbed oxygen, and low-temperature reducibility (below 400 °C) and from the highest to the lowest value were LaCoO3-M > LaCoO3-C > LaCoO3-S, which was in good agreement with the simultaneous oxidation abilities for NO and Hg0. Furthermore, it was found from XPS and in situ DRIFTS that the oxidation products of Hg0 were all HgO species, not Hg(NO3)2 species, and the intermediate oxidation products of NO were also different, but all subsequently formed NO2. In conclusion, the selection of preparation method is a key parameter for optimizing the catalytic activity on perovskite.