La0.8Sr0.2MnO3 MgAl2O4丝网蜂窝催化剂用于低浓度甲烷催化燃烧

Development and Application of La0.8Sr0.2MnO3/MgAl2O4 wire-mesh honeycombs in catalytic combustion of air diluted methane

摘要:

采用沉积-沉淀法制备了与镁铝尖晶石（MgAl2O4, MA）载体复合的镧锶锰钙钛矿(La0.8Sr0.2MnO3, LSM)催化剂LSM/nMA。首先考察MA与LSM的摩尔比n、前驱体老化和焙烧温度等制备条件的影响，在程序升温微反应器中测试了LSM/nMA粉体对低浓度甲烷催化燃烧反应的活性，并用FTIR、H2-TPR、BET、XRD和SEM等手段对催化剂进行表征。实验发现在10℃老化和800℃下焙烧的LSM/4MA活性最佳，T50为489.4℃，活化能Ea为112.5kJ/mol，BET比表面积仍有81.6m2/g，表现出较好的抗烧结性能。然后用浆料涂覆法依次将第二载体(MA)和LSM/4MA粉体涂覆在Fe-Cr-Al合金丝网上制得丝网蜂窝催化剂。考察了第二载体及LSM/4MA粉体涂覆量的影响，在空速40000h-1条件下测试了蜂窝催化剂的活性，得出了MA的最佳涂覆厚度在20?m左右，LSM/4MA的最佳涂覆量约为2.65mg/cm2。

Abstract:

The composite powders of La0.8Sr0.2MnO3 (LSM) perovskite and MgAl2O4 (MA) spinel, named as LSM/nMA were prepared by deposition-precipitation method. The impact of preparation factors, such as the molar ratio of MA to LSM (n), the aging temperature and calcination temperature of precursors was investigated. The activity of the composite powder was examined in the temperature-programmed micro reactor for catalytic combustion of air diluted methane，and the properties of catalysts were characterized by FTIR, H2-TPR, BET, XRD and SEM. The LSM/4MA catalyst which precursor aged at 10℃ and calcined at 800℃ demonstrated the best activity with T50 489.4℃ and Ea 112.5kJ/mol and excellent sintering resistance with SSA of 81.6m2/g . Afterwards, the wire-mesh honeycomb catalysts were developed by dip-coating sequentially the slurries of MA and LSM/4MA powders. Influences of the loading of MA and LSM/4MA coating were investigated respectively in reactions at GHSV of 40000/h, which gave the best amount in preparation of the wire-mesh honeycombs and the proper coating thickness of MA is around 20?m, the best loading of LSM/4MA is about 2.65mg/cm2.