Preparation Of Monolithic Wire-Mesh Perovskite-Type Catalyst And Its Characteristic Of Catalytic Combustion Of VOCs

The catalysts of the ceramic honeycombs coated with precious metal are recently applied widely in catalytic combustion of volatile organic compounds (VOCs). However, the poor thermal stability of precious metal, and heat-mass transfer of single structure lead to low efficiency and high cost of cirdierite honeycomb catalysts in catalytic combustion. The catalysts made of metal wire mesh with the three-dimensional pores have many advantages such as the higher thermal conductivity, mechanical strength, high heat and mass transfer rates in the catalytic combustion of VOCs. So it is worthy to research the methods of preparation of high heat and mass transfer efficiency monolithic metal wire-mesh catalysts coated with cheap active materials.In our dissertation, the wire mesh with high bond strength of Al₂O₃/Al membrane carrier was assembled into monolithic structure, which was then applied in catalytic combustion of VOCs after wash-coated with La_0.8Sr_0.2MnO₃. Some conclusions were drawn as follows:1. Preparation of well-adhered membrane carrierA well-adhered and high surface area Al₂O₃/Al membrane carrier (10.2 m²/g) which was formed on the wire mesh surface after electrophoretic deposition and thermal treatment, it was only lost 0.5wtï¼…of total weight after 30 minutes ultrasonic vibration. We obtained the best preparation parameters of concentration of additives, the way of applied voltage, temperature of thermal treatment.2. Preparation of La_0.8Sr_0.2MnO₃ and Au doping La_0.8Sr_0.2MnO₃The La_0.8Sr_0.2MnO₃ was prepared by the co-deposition using NaOH and Na₂CO₃ as precipitators, the catalytic combustion of toluene was took as a probe to investigate the catalytic activity of La_0.8Sr_0.2MnO₃. The result showed that La_0.8Sr_0.2MnO₃ had unique perovskite phase. The catalyst prepared with NaOH/Na₂CO₃=1 showed best catalytic activity.The La_0.8Sr_0.2MnO₃ doped with the 0.5wtï¼…Au content was synthesized by the co-precipitation (CP) and the deposition-precipitation (DP) respectively. On the basis of H₂-TPR data and catalytic combustion of toluene, it had been found that the catalytic activity of the catalysts were enhanced because of the Au enhanced the reactivity of the LSM surface capping oxygen. The catalytic properties of Au-LSM were similar to that of the commercial catalyst of Pt-Pd/Al₂O₃.3. The properties of monolithic metal wire-mesh La_0.8Sr_0.2MnO₃ catalystsThe catalytic properties of the different forms of catalysts (Powder,Ceramic honeycomb,wire-mesh) were investigated in catalytic combustion of toluene, the results showed that the monolithic metal wire-mesh La_0.8Sr_0.2MnO₃ catalysts had the same catalytic performance as the La_0.8Sr_0.2MnO₃ powder catalysts. However, the wire-mesh catalysts showed the fastest thermal response and the best isothermal of catalyst bed. The catalytic combustion of volatile organic polycomponents on the monolithic metal wire-mesh catalysts was investigated. The results suggested that acetone had no effect on the catalytic combustion of toluene but the ethyl acetate could enhance the performance of the catalytic combustion of toluene.