Study On Catalytic Combustion Of VOCs By Perovskite Supported On Zeolites

Volatile organic compounds(VOCs) are main air pollutions. The boiling point of VOCs is between 50 ℃-250 ℃ and saturated vapor pressure is more than 133.3 Pa at room temperature. A majority of VOCs are seriously harm to human health and environment, especially to atmospheric environmental quality. The main elimate methods of VOCs include adsorption, condensation, photocatalysis and catalytic combustion.etc. Catalytic combustion has been attracted much attention because of low energy consumption and no secondary pollution. Catalyst with high activity is the key to the catalytic combustion technology. In addition, the type of the supporter plays an important role in the process of catalytic combustion. In order to explore the effect of zeolite support in the catalytic combustion process, zeolite supported Pd/La0.8Ce0.2Mn O3 has prepared by impregnation. The catalysts are characterized by XRD, BET, SEM, H2-TPR.The research achieve the following results:ZSM-5 and MCM-41 were used as excellent carriers which supported the type of perovskite. It sufficiently exhibited high activity and reduced perovskite ignition temperature by doping amount of Pd to perovskite supported on zeolite simultaneously. La0.8Ce0.2Mn O3/ZSM-5 had catalyst higher catalytic activity of toluene, when doping amount of Pd was 0.3%, loading amount of perovskite was 20% under calcination temperature of 750 ℃. Characterization results revealed that the catalyst had a complete perovskite structure and modification of Pd improved catalytic performance significantly. The interaction between perovskite structure La0.8Ce0.2Mn O3 microcrystalline and Pd, which improved the adsorption for O22-/O- and enhanced transmission performance of lattice oxygen species. The Pd/La0.8Ce0.2Mn O3/MCM-41 catalyst showed the better performance as the amount Pd modification was 0.05%, loading amount perovskite was 20% under calcination temperature at 750 ℃. Characterization results showed that Pd/La0.8Ce0.2Mn O3/MCM-41 catalyst belonged to perovskite structure, Pd was highly dispersed on surface of perovskite. What is more, MCM-41 was played a good supporter which had been greatly improved catalyst specific surface area. Investigation results of different types of the zeolite(HZSM-5、ZSM-5、USY、MOR、Na Y and β)supported Pd/La0.8Ce0.2Mn O3 on catalyst performance. It revealed that the acidic and specific surface area of catalyst played important role to catalytic activity. The acid site of catalyst carrier was rich if the acidity was strong, and then catalyst activity was better; Under the premise of acidity was strong, the smaller acid sites loss which covered by Load active component if surface area was bigger, and come to better catalyst activity. With the noble metal doping, the interaction of the supporter and La0.8Ce0.2Mn O3 perovskites had been weakened. The oxygen storage performance can not be one of the factors that influence the catalytic activity. The supporter USY was selected due to it had strong acidic and large surface,Pd/La0.8Ce0.2Mn O3/USY catalyst generally maintained a high activity for the one-component "BTX system".