采用沉积-沉淀法制备了Al2O3和MOx-Al2O3 (M=Fe,Zn)负载型金催化剂.室温下对其CO氧化及富氢条件下CO选择氧化催化活性进行了广泛的研究.催化剂床层温度由热电偶直接测定.催化剂表面温度与O2/CO的体积比以及CO和H2的浓度密切相关.在CO氧化反应过程中Au/Al2O3催化剂的温度可高达170℃,添加FeOx可使其降至55 ℃.利用一系列仪器(X射线衍射仪,X射线光电子能谱仪和透射电镜等)对催化剂的结构进行了表征.结果显示Al2O3负载型金催化剂热点的形成可以通过添加合适的助剂很好地控制.助剂的添加能够使催化剂活性中心由金属态Au变为Au(m),从而导致了CO选择氧化反应机理不同.%Au catalysts supported on Al2O3 and MOx-Al2O3 (M=Fe and Zn) were prepared by the deposition-precipitation method.Their catalytic activities for CO oxidation in the absence and presence of an H2-rich steam at room temperature were investigated in detail.Catalyst bed temperatures were determined directly by a thermocouple.The catalyst surface temperature depended on the volume ratio of O2/CO,and the concentrations of CO and H2.The temperature on the Au/Al2O3 surface can reach 170 ℃ during CO oxidation,and is decreased to 55 ℃ by addition of FeOx.These results indicate that formation of hot-spots on Y-alumina-supported gold catalysts could be controlled by adding an appropriate dopant.The structure of the catalysts was characterized by techniques such as X-ray powder diffraction,X-ray photoelectron spectroscopy and transmission electron microscopy.Addition of a dopant could transfer the active center from Au to Au(m),which resulted in different reaction mechanisms of preferential oxidation of CO in the presence of H2.
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