PdO-CeO2复合氧化物催化剂的CO低温氧化  

PdO-CeO_2 Composite Catalysts for Low Temperature CO Oxidation

作　　者：肖小燕[1] 鲁继青[1] 苏孝文[1] 郭明[1] 罗孟飞[1] 

机构地区：[1]浙江师范大学物理化学研究所,浙江省固体表面反应化学重点实验室,浙江金华321004

出　　处：《物理化学学报》2009年第3期561-566,共6页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20473075);浙江省自然科学基金(Y407020);浙江省钱江人才计划(QJD0702098)资助

摘　　要：采用共沉淀法制备了一系列不同Pd含量的PdO-CeO2复合氧化物催化剂,并考察了该催化剂的CO低温氧化反应催化性能.运用X射线衍射(XRD),物理吸附(BET),CO化学吸附,程序升温还原(TPR),脉冲反应等技术对催化剂进行了表征.XRD结果表明,焙烧温度从400℃升高到800℃,有利于CexPd1-xO2-δ固溶体的形成.然而焙烧温度升至1000℃时,导致Pd从固溶体中析出.催化剂的CO氧化活性(TOF)与CexPd1-xO2-δ固溶体的含量存在一定的对应关系.随着CexPd1-xO2-δ固溶体含量的增加,CO氧化的TOF值大,可见CexPd1-xO2-δ固溶体的形成对CO氧化活性有着主要的贡献.在催化剂焙烧温度相同的条件下,催化剂的CO氧化活性与Pd粒子大小无对应关系.脉冲反应进一步说明PdOx的CO氧化活性高于金属Pd.A series of PdO-CeO2 composite catalysts were prepared using a co-precipitation method and tested for low temperature CO oxidation. The catalysts were further characterized by X-ray diffraction （XRD）, the Brunauer- Emmett-Teller （BET） technique, chemisorption of CO, temperature programmed reduction （TPR）, and a pulse reaction technique. Results of XRD indicated that CexPd1-xO2-δ solid solution was formed when the catalysts were calcined at 400-800 ℃, while PdO or metal Pd species re-migrated to the catalyst surface when it was calcined at a higher temperature （1000 ℃）. The turnover frequency （TOF） for the CO oxidation reaction over these catalysts was found to be independent on the Pd particle size and it increased with increasing the content of CexPd1-xO2-δ solid solution in the catalyst. This suggests that the solid solution might be the active phase for the reaction. Furthermore, pulse reaction results indicated that oxidized Pd species were more active than metallic Pd.

关 键 词：PdO-CeO2 CO氧化 CexPd1-xO2-δ固溶体 

分 类 号：O643.36[理学—物理化学]