Au/Cu_xMn_yO_z催化剂的制备、表征及其CO消除性能

Preparation and Characterization of Au/Cu_xMn_yO_z Catalyst and Its Catalytic Performance for CO Removal

采用溶胶-凝胶法制备了新型CuxMnyOz复合氧化物,并利用沉积-沉淀法制备了1%Au/CuxMnyOz系列催化剂样品,在富H2条件下评价了该催化剂在CO选择性氧化反应和水煤气变换(WGS)反应中的催化性能.结果发现,极少量Au的负载使得CuxMnyOz复合氧化物不仅具有良好的CO氧化活性和选择性,而且在WGS反应中也表现出较高的催化性能.运用N2物理吸附、X射线粉末衍射、X射线光电子能谱、X射线荧光分析、透射电镜和H2程序升温还原等技术对催化剂的物化性质进行表征后发现,CuxMnyOz复合氧化物主要是以类尖晶石相的Cu1.5Mn1.5O4形式存在,其含量与催化剂样品的活性呈对应关系;负载的Au物种大部分是以金属态Au0粒子形式分散在复合氧化物上,并与其中Cu1.5Mn1.5O4形成良好的协同效应,从而提高了催化剂的还原能力.

This paper presented the study on the catalytic performance of a deposition-precipitation prepared Au catalyst supported on cop-per-manganese complex oxide,which was synthesized via a sol-gel method. This Au/CuxMnyOz catalyst with a low Au content exhibited high activity for both preferential CO oxidation and water-gas shift reaction. The structure-activity relationship was investigated by N2 physisorp-tion,X-ray diffraction,transmission electron microscopy,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,and X-ray fluorescence characterization. The results revealed that the CuxMnyOz samples exist mainly in the form of nonstoichiometric spinel Cu1.5Mn1.5O4 phase,which favors the CO conversion in both CO removal reactions. Most Au species dispersed onto the surface of Cu-Mn complex oxide in the metallic state of Au0. The relatively strong interaction between Au and support enhanced the reducibility of Au/CuxMnyOz catalyst,which is also responsible for the excellent performance of the as-prepared catalyst.