硬模板法制备铈基复合氧化物及其对甲苯燃烧的催化性能

采用硬模板法制得CeM-HT(M=Cu、Mn、Fe和Co)复合氧化物催化剂,借助XRD、BET、O₂-TPD和H₂-TPR研究了催化剂的物理化学性质,通过甲苯催化燃烧探针反应评价了催化剂的催化性能。结果表明,CuO、MnO_x、FeO_x和Co₃O₄能溶入CeO₂晶格形成Ce-O-Cu、Ce-O-Mn、Ce-O-Fe和Ce-O-Co固溶体,Cu和Mn离子的溶入导致CeO₂晶格发生了较大程度的晶格畸变,Fe和Co离子对CeO₂晶格的影响较小,且在CeCo-HT氧化物催化剂中还存在微量晶相Co₃O₄。所制得的CeM-HT氧化物催化剂表现出了优越的甲苯催化燃烧性能,在反应温度为300、270、260和230 ℃时,CeFe-HT、CeCo-HT、CeMn-HT和CeCu-HT氧化物催化剂上甲苯的催化燃烧转化率分别达93.7%、95.0%、96.5%和95.0%以上。Ce基复合氧化物催化剂的甲苯催化燃烧活性顺序与其氧脱附性能、储氧性能和可还原性能具有正相关性,遵从顺序为CeCu-HT > CeMn-HT > CeCo-HT > CeFe-HT。

Catalytic combustion of toluene over the Ce-based composite oxides prepared by hard-template methods

Ce-based composite oxides (CeM-HT, M=Cu, Mn, Fe, and Co) were prepared by the hard-template method and characterized by XRD, O₂-TPD, nitrogen physisorption, and H₂-TPR; their catalytic performance in toluene combustion was investigated. The results show that CuO, MnO_x, FeO_x, and Co₃O₄ can be well dissolved into the CeO₂ lattice, forming Ce-O-Cu, Ce-O-Mn, Ce-O-Fe, and Ce-O-Co solid solutions, respectively. The CeO₂ lattice is significantly distorted by the incorporation of Cu and Mn ions, but less affected by the doping of Fe and Co ions. Moreover, a little amount of Co₃O₄ crystal exists in the CeCo-HT oxide catalyst. The Ce-based composite oxides exhibit excellent catalytic performance in toluene combustion; the toluene conversions over CeFe-HT, CeCo-HT, CeMn-HT, and CeCu-HT oxide catalysts reach 93.7% at 300 ℃, 95.0% at 270 ℃, 96.5% at 260 ℃, and 95.0% at 230 ℃, respectively. The catalytic activity of the Ce-based composite oxides is closely related to their oxygen desorption amount, oxygen storage capacity, and reducibility, following the order of CeCu-HT > CeMn-HT > CeCo-HT > CeFe-HT.