金的化学状态对Au／CoCeOx催化剂CO氧化性能的影响

以CoCeOx复合氧化物为载体,采用沉积沉淀法制备了负载型的金催化剂,并通过不同温度的预处理控制Au的化学状态. 使用粉末X射线衍射、高分辨透射电子显微镜、程序升温还原和X射线光电子能谱对催化剂进行了表征,考察了在室温条件下该系列催化剂的一氧化碳氧化性能. 结果表明, Au/CoCeOx催化剂的CO氧化性能与催化剂表面Au 的含量成正比, Au 可能是反应的主要活性物种. 添加水汽对反应有一定的促进作用,但由于Au 不能稳定存在,特别是当催化剂表面Au 的含量过高时,在水汽的作用下Au 迅速发生歧化反应,使得催化剂的性能下降.

Influence of Chemical States of Au on CO Oxidation over Au/CoCeOx Catalyst

Au/CoCeOx catalysts were prepared by a deposition-precipitation method.Au chemical states were controlled by varying the temperature of pretreatment in an oxygen-containing atmosphere.The catalysts were characterized by powder X-ray diffraction,high-resolution transmission electron microscopy,temperature-programmed reduction,and X-ray photoelectron spectroscopy.The catalytic performance for CO oxidation was investigated at ambient temperature.It was found that the conversion of CO increased with increasing amount of Au in the catalyst,and thus the cationic gold(Au ) was considered the main active species.Addition of water vapor to the feed gas promoted CO conversion to some degree,but the catalytic performance decreased rapidly due to the disproportionation of Au to Au3 and Au0,particularly for the catalyst that contained relatively large amounts of Au species.