Preparation Of Perovskite-Type LaMnO₃ Catalysts By Hard-Template Method And The Catalytic Combustion Performance Of VOCs

Catalytic combustion is considered to be an efficient technology for the abatement of volatile organic compounds. Supported noble metal catalysts exhibit high catalytic activities at lower temperature, and have been widely applied in industrialized VOCs elimination. However, these catalysts are expensive and easily sintering at higher temperature. LaMnO3 perovskite-type catalysts are expected to be the alternative of noble metal catalysts because of their low price, high catalytic activity and excellent thermal stability.In this dissertation, a series of LaMnO3 catalysts were synthesized by the hard-template method, and characterized by XRD, BET, SEM, TG, H2-TPR. Their catalytic combustion performance was tested using toluene combustion as probe reaction. Conclusions were listed as follows:Firstly, a series of LaMnO3 catalysts were synthesized using PMMA as hard template. The results indicated that the appropriate mass ratio (MMA: LaMnO3) could heighten the specific surface area and improve redox properties, thus enhance the catalytic activities of LaMnO3 catalysts. When the mass ratio (MMA:LaMnO3) is 2:1, the LaMnO3 catalysts could reach the largest specific surface area and obtain the highest catalytic activity.Secondly, a series of LaMnO3 catalysts were synthesized using AC as hard template. The results indicated that the appropriate mass ratio (AC LaMnO3) could heighten the specific surface area and improve redox properties, thus enhance the catalytic activities of LaMnO3 catalysts. When the mass ratio (AC:LaMnO3) is 1:10, the LaMnO3 catalysts could reach the largest specific surface area and obtain the highest catalytic activity.Thirdly, in order to improve the catalytic activity of LaMnO3, quartz sand was added during the preparation process and noble metal Pd was doped to LaMnO3. The study indicated that both the quartz sand and Pd can improve the catalytic activity.Finally, the reaction mechanism of VOCs conversion on LaMnO3 was studied based the results of characterization and catalytic combustion. The possible active center and reaction model were obtained.