La_(1-x)Sr_xMnO_3催化剂的催化甲烷脱硝性能

Selective Catalytic Reduction of NO_x by Methane over La_(1-x)Sr_x MnO_3 Perovskites

采用溶胶．凝胶法和过量浸渍法分别制备了粉末状及负载型La（1-xSrxMn03＆为0、0．2和0．4）催化剂，并用XRD、SEM对其进行表征，以及检验负载型催化剂在无氧和有氧条件下催化甲烷脱硝的活性．结果表明，掺杂sr不会改变钙钛矿特有的晶型结构，并且在Sr摩尔分数为0．2时，催化剂还出现了多孔结构．同时Lao8Sro2Mn03和La0.6Sr0.4MnO3两种催化剂在无氧条件下都具有较好的活性，脱硝效率在800～900。C条件下能够达到90％以上．在氧体积分数为6％时，L00RSro2Mn03在800℃时具有较高的催化活性，脱硝效率仍达到80％，Lao6Sro4Mn03在高温区的催化活性则受到氧气存在的抑制．在有氧条件下，两种催化剂还能相应地提高500～600℃下的脱硝效率．

Powder perovskite-type La1-xSrxMnO3 （x = 0,0.2,0.4）were synthesized by sol-gel method, and supported La（1-x SrxMnO3 （x = 0.2, 0.4）were synthesized by excessive dipping method. The powders were characterized by XRD and SEM, and supported catalysts were then submitted to activity tests in the selective catalytic reduction （SCR） of NO by meth- ane with or without 02. The experimental results showed that the crystal structure of St-substituted samples was the charac- teristic perovskite structure, and what＇s more, La0.8 Sr0.： MnO3 possessed a porous structure. In the absence of 02, the reduction of NOx by CH4 was performed over Lao.8 Sro.2 MnO3 and Lao.6 Sro.4 MnO3, leading to a maximum of 90% at 800--- 900 ~C. The catalytic performance of Lao.8 Sro.2 MnO3 could reach a maximum of 80% at 800 ~C with 6% 02, on the other hand, the performance of Lao.6 Sro.4 MnO3 was suppressed by the presence of 02. The catalytic performance was improved by both Lao.8 Sro.2 MnO3 and Lao.6 Sro.4 MnO3 at 500---600 ℃