铈钛氧化物载体对La_(0.8)Ce_(0.2)MnO_3催化燃烧甲苯性能的影响

Effect of Cerium-Titanium Oxide Support on Catalytic Combustion of Toluene Performance of La_(0.8)Ce_(0.2)MnO_3

以复合氧化物CeO_2-TiO_2为载体、La_(0.8)Ce_(0.2)MnO_3为活性组分,采用等体积浸渍法制备了氧化物负载型催化剂La_(0.8)Ce_(0.2)MnO_3/CeO_2-TiO_2(记为La/Ce_xTi)。以甲苯为模型污染物,考察了载体的制备方法、n_(Ce)/n_(Ti)、焙烧温度、钙钛矿负载量对催化剂活性的影响。并采用XRD对催化剂进行了表征分析。结果表明,以共沉淀法制备的CeO_2-TiO_2作为载体负载钙钛矿活性组分制备的La/Ce_xTi催化剂表现出较高的催化活性;当采用载体中n_(Ce)/n_(Ti)为0.5、活性组分负载质量分数为20%、焙烧温度为600℃时制备的La/Ce_xTi催化剂,甲苯完全转化温度为240℃。CeO_2-TiO_2复合氧化物载体以非晶态Ce_xTi_(1-x)O_2固溶体形式存在,钙钛矿均匀分散在载体的表面,载体对于催化剂活性的提高起到协同效应。

Supported perovskite catalysts La0.8 Ce0.2 MnOa/CeO2-TiO2 named La/Ce0.2Ti were prepared by incipient-wetness impregnation by using CeO2-TiO2 mixed oxide and La0.8 Ce0.2MnO3 as the support and active phase, respectively. The effects of support preparation method, nce/nTi, calcination temperature and the perovskite loading on the catalytic performance of La/CexTi in catalytic combustion of toluene were investigated. The catalysts were characterized by XRD. The results showed that the support prepared by coprecipitation was a suitable carrier for La/Ce^Ti catalyst, which possessed the better catalytic activity in toluene combustion. By using the La/Ce^Ti, prepared with the nce/nTi of 0.5, loading capacity of 20%, and the calcination temperature of 600~C, as catalyst, the complete combustion temperature of toluene was only 240~C. In La/Ce^Ti catalyst CeO2-TiO2 existed in the form of amorphous solid solution and the perovskite uniformly dispersed in the surface of CeO2-TiO2. The synergistic interaction between the active phase and the carrier played an important role in the catalyst activity enhancement.