Catalytic Combustion Performance Of 12SrO·7Al₂O₃ Supported La_0.8Sr_0.2MnO₃ And CuMn₂Ce₄ Monoliths

Catalytic combustion is considered to be an efficient technology for the abatement of volatile organic compounds at lower temperature, compared to thermal combustion, thus preventing influence of air pollutants. Transition metal oxide catalysts La_0.8Sr_0.2MnO₃ and CuMn₂Ce₄ are expected to be the alternative of noble metal catalysts because of their low price, high catalytic activity and excellent thermal stability. In order to lower the pressure drop and improve the efficiency of mass transfer, catalysts usually are made into ceramic honeycomb monoliths in practical use. The washcoat is very important for the thermal stability of the transition metal oxide catalysts. The high temperature thermal stability ofγ-Al₂O₃ washcoat can be enhanced by modification of rare earth metals and/or alkaline earth metals. In this dissertation, 12SrO·7Al₂O₃ was synthesized by the solid reaction and used as the washcoat of a cordierite monoliths. And their catalytic performances were evaluated using methyl methacrylate combustion as detection reaction. Conclusions were listed as follows:Firstly, compared to Sr_0.3Ba_0.5La_0.2MnAl₍11_O19 hexaaluminate andγ-Al₂O₃, the 12SrO·7Al₂O₃ washcoat improved the properties of the monolithic catalyst clearly. After calcined at 850 oC with 6 h, the monolith with 12SrO·7Al₂O₃ washcoat still could fully convert methyl methacrylate at about 260 oC, while the monoliths with Sr_0.3Ba_0.5La_0.2MnAl₍11_O19 andγ-Al₂O₃ washcoats needed 320 oC and 340 oC respectively. The results of BET and SEM indicated that the promotion effect was not originated from the BET surface area of 12SrO·7Al₂O₃, while the existence of the 12SrO·7Al₂O₃ prevented the sintering of the La_0.8Sr_0.2MnO₃ species and kept the dispersing degree of these particles, which heightened the activity and thermal stability of the monolith perovskites.Secondly, A cordierite honeycomb monolithic CuMn₂Ce₄ catalyst was prepared by impregnation method, using 12SrO·7Al₂O₃ as washcoat. The catalytic performance of catalyst was tested, and the results showed that higher catalytic activity could be obtained with 12SrO·7Al₂O₃ was washcoat. The stabilization of the active components was kept better after high temperature calcinated than catalysts without washcoats. In addition, In this dissertation, 12SrO·7Al₂O₃ was synthesized by the solid reaction and used as the washcoat of a cordierite monoliths. And their catalytic performances were evaluated using methyl methacrylate combustion as detection reaction. Conclusions were listed as follows:Firstly, compared to Sr_0.3Ba_0.5La_0.2MnAl₍11_O19 hexaaluminate andγ-Al₂O₃, the 12SrO·7Al₂O₃ washcoat improved the properties of the monolithic catalyst clearly. After calcined at 850 oC with 6 h, the monolith with 12SrO·7Al₂O₃ washcoat still could fully convert methyl methacrylate at about 260 oC, while the monoliths with Sr_0.3Ba_0.5La_0.2MnAl₍11_O19 andγ-Al₂O₃ washcoats needed 320 oC and 340 oC respectively. The results of BET and SEM indicated that the promotion effect was not originated from the BET surface area of 12SrO·7Al₂O₃, while the existence of the 12SrO·7Al₂O₃ prevented the sintering of the La_0.8Sr_0.2MnO₃ species and kept the dispersing degree of these particles, which heightened the activity and thermal stability of the monolith perovskites.Secondly, A cordierite honeycomb monolithic CuMn₂Ce₄ catalyst was prepared by impregnation method, using 12SrO·7Al₂O₃ as washcoat. The catalytic performance of catalyst was tested, and the results showed that higher catalytic activity could be obtained with 12SrO·7Al₂O₃ was washcoat. The stabilization of the active components was kept better after high temperature calcinated than catalysts without washcoats. In addition,...