The selective catalytic reduction of NO_x with CH₄ on La_1-xSr_xMnO₃ (x=0.2, 0.4) catalysts

Two kinds of typical perovskite catalysts La_1-xSr_xMnO₃ (x=0.2, 0.4) as new catalysts for using in CH₄-NO and CH₄-N₂O reaction is proposed, and the preparation method, characterization, catalytic activity of La_1-xSr_xMnO₃ was investigated. The catalysts powder via sol-gel method was successfully synthesized in this paper. In addition, the catalytic activity of supported La_1-xSr_xMnO₃ catalyst was tested in fixed bed reactor, and the effects O₂ concentration on catalyst activity were explored at three different temperatures, 600°C, 700°C and 800°C. The catalytic reduction of NO and N₂O by CH₄ over La_0.8Sr_0.2MnO₃ and La_0.6Sr_0.4MnO₃ catalyst was performed separately. The conversion ratio of N₂O was usually higher than that of NO when the temperature and other conditions were the same. With the decrease of temperature, the range of O₂ concentration becomes narrower obviously on the NO conversion. However, the O₂ content doesn't seem to have significant in fluence on the N₂O conversion ratio. The La_0.8Sr_0.2MnO₃ performed better on the reaction of CH₄ and N₂O when temperature increased, wh ile the La_0.6Sr_0.4MnO₃ performed best on 700°C with a ratio of about 90%.