Study On Preparation And Activition Of Supported Catalysts For Reduction Of Sulfur Dioxide By Monoxide Carbon

Extensive research had been done on catalytic oxidation of CO, removal of NOx, electrochemical reduction of O2, desulfurization and denitrification of vehicle exhaust. Especially, the high activity received a great deal of attention, but industrial application had not been conducted on flue gas desulfurization because of high activation temperature, deactivation in the presence of O2, low specific surface. The preparation methods including sol-gel, coprecipitation, mechanical ball milling method, spontaneous firing, micro-emulsion polymerization and ultrasound-sol were usually used to prepared LaCoO₃ catalysts.In this paper, catalysts were prepared with sol-gel method and coprecipitation method, LaCoO₃ was supported onγ-Al₂O₃ with ultrasound-sol method to prepare LaCoO₃/γ-Al₂O₃. The preparation processes of sol-gel method and coprecipitation method were investigated, the samples were characterization by XRD, SEM, TG-DTA, the optimality preparation conditions were obtained. In order to investigate supporting mechanism of LaCoO₃ onγ-Al₂O₃, La₂O₃-Co₃O₄/γ-Al₂O₃ was prepared with coprecipitation, and compared with LaCoO₃, La₂O₃-Co₃O₄. Finally, LaCoO₃/γ-Al₂O₃ was prepared with ultrasound-sol method; the results showed that this catalyst had a better low temperature activity and activation temperature.The XRD and SEM results showed that the dispersion degree had great influence on LaCoO₃ phase, citric acid and ultrasound induced good dispersion of La, Co ion on support. Citric acid contribute to reduce calcinations temperature, complete perovskite phase can be obtained at n(citric acid):n(La3+):n(Co2+)=3:1:1. Ultrasound prevented the blocking of microspores that reduced specific surface. The research of La₂O₃-Co₃O₄/γ-Al₂O₃ showed that small amount LaCoO₃ had formed, XRD of sulfurized sample results showed that the sample with perovskite construction can sulfide easily, however, single La, Co oxide sulfide difficultly, La₂O₃-Co₃O₄/γ-Al₂O₃ had better low temperature activity than LaCoO₃。The catalyst LaCoO₃/γ-Al₂O₃ prepared ultrasound-sol method had more LaCoO₃ phases than La₂O₃-Co₃O₄/γ-Al₂O₃, the activation temperature was 400℃, had better low temperature activity too.