多孔LaMO_3(M=Co,Fe)纳米催化剂的制备及一氧化碳催化氧化性能

Preparation of porous LaMO_3(M=Co,Fe)nanocatalysts and their catalytic activities for CO oxidation

钙钛矿型氧化物催化剂(ABO3)具有廉价易得、高热稳定性、催化活性高的优点,在催化一氧化碳(CO)低温脱除领域具有重要的理论研究意义和实际应用价值。本研究中,以聚苯乙烯(PS)微球、碳微球为模板,硝酸镧、硝酸钴、硝酸铁为金属源,柠檬酸为络合剂,通过溶胶-凝胶法制备了多孔LaCoO_3和多孔LaFeO_3催化剂。采用X射线衍射、热重-差热、扫描电镜、透射电镜和氮气吸附-脱附等手段对所得样品进行了系统表征分析。结果表明:所制备的催化剂具有高纯度和高热稳定性。加入11.12g PS微球所制备的多孔LaCoO_3催化剂平均颗粒粒径为13nm,加入0.5g碳微球制备的多孔LaFeO_3催化剂平均粒径为19nm,且具有介孔和微孔分级孔结构。催化性能测试结果表明:在同等条件下对CO转化率达到50%时,多孔LaCoO_3和多孔LaFeO_3使得催化温度分别降低了43℃和32℃;CO完全转化温度则分别降低了90℃和60℃。

The perovskite type catalyst （ABO3） has the advantages of cheap availability, high thermalstability and high catalytic activity, and has important theoretical research value and practical applicationvalue in the field of catalyzing the low temperature removal of carbon monoxide （CO）. In this study,porous LaCoOa and porous LaFeO3 nanoparticles catalyst were prepared by sol-gel method usingpolystyrene （PS） microspheres, carbon microspheres as template, lanthanum nitrate, cobalt nitrate,ferric nitrate as metal source and citric acid as complexing agent. The samples were characterized by X-ray diffraction, thermogravimetry-differential thermal, scanning electron microscope, transmissionelectron microscope and nitrogen adsorption-desorption. The results show that the synthesized catalysthas high purity and high thermal stability. The average particle size of the porous LaCoO3 catalystprepared by adding 11.12g of PS microspheres was 13nrn. The porous LaFeO3 catalyst prepared byadding 0. 5g of carbon microspheres was 19nm, and they both have the mesoporous and microporouspore structure. The results showed that the CO conversion temperature of porous LaMO3 was reduced by43~C and 32~C when the CO conversion reached 50~ compared with the LaMOawithout template underthe same conditions. The CO complete conversion temperature was reduced by 90~C and 60~C.