Study On Catalytic Combustion Of VOCs By Perovskite Supported On Oxide

Volatile organic compounds?VOCs?are main air pollutions and seriously harmful to human health and environment.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 support plays an important role in the process of catalytic combustion.In order to explore the effect of oxide support in the catalytic combustion process,oxide supported La_0.8Ce_0.2MnO₃ has prepared by impregnation.The catalysts are characterized by XRD,BET,SEM,H₂-TPR.The research achieve the following results:The nature of the catalyst support plays an important role in catalytic combustion reaction of toluene.Al₂O₃?TiO₂?CeO₂ were excellent supports for perovskite loaded.It sufficiently exhibited high activity and reduced perovskite ignition temperature,especially La_0.8Ce_0.2MnO₃/CeO₂ catalyst had the highest catalytic activity of toluene,when loading amount of perovskite was 15% under calcination temperature of 600 ?.Characterization results revealed that,for the oxide support,the specific surface area,surface acidity and other beneficial properties can affecting the catalyst activity,but more important factors is the oxygen storage performance of the support;so for the La/CeO₂ catalyst,the interaction between the support and the active phase which improved the adsorption for O₂2-/O-and enhanced transmission performance of lattice oxygen species.CeO₂ surface area studies showed the important role to catalytic activity.The catalyst activity increases as the surface area of the support increases under the oxygen storage catalyst performance equal.The support with a larger surface area is beneficial to the dispersion of the active phase on ceria surface,thus it can provide more active sites,which is beneficial to catalytic combustion.Different morphologies of supports have different oxidation reduction capability,which causes the differents catalytic activity.La/Ce O₂ nanocubes has good oxygen storage performance,but its larger particle size and mesoporous structure limited the improvement of catalytic activity;while the nanoparticles showed a high specific surface area,small particle size,more oxygen vacancies and highly reactive oxygen species,therefore,in the catalytic oxidation of toluene it can exhibit the highest catalytic activity.CeO₂-TiO₂ composite oxide support La_0.8Ce_0.2MnO₃ on catalyst performance was investigated.The result show that when using the sol-gel method,Ce/Ti molar ratio of 0.5:1,the perovskite loading of 20%,calcination temperature at 600 ?,the catalytic have the best performance,the light-off temperature is 130 ?,complete combustion temperature is 250 ?.Characterization results showed that,when Ce/Ti ratio of 0.5:1,the support formed Ce_xTi_1-xO₂ solid solution,and has Ce_0.5Ti mesoporous structure,large specific surface area and superior performance on oxide oxygen storage than a single oxide.These characteristics of support play a crucial role on expressing of perovskite activity.