固相浸渍法和湿浸渍法制备CuO/CeO_2催化剂及其CO氧化性能的对比研究

Comparative study on the catalytic CO oxidation properties of CuO/CeO_2 catalysts prepared by solid state and wet impregnation

采用固相浸渍法和常规湿浸渍法制备了一系列CuO/CeO2催化剂,并结合X射线衍射(XRD)、氢气-程序升温还原(H2-TPR)、激光拉曼光谱(LRS)、原位漫反射红外光谱(in situ DRIFTS)、X射线光电子能谱(XPS)等手段考察了制备方法对催化剂结构性质及其在CO氧化反应中性能的影响.XPS和H2-TPR结果表明,固相浸渍法更有利于得到高分散的铜物种,并促进CuO物种的还原.LRS结果表明,相比于湿浸渍法,固相浸渍法能产生更多氧空位,而这些氧空位可以活化参与反应的O2.CO氧化活性测试结果表明,当铜负载量相同时,固相浸渍法制备的催化剂相比于湿浸渍法表现出更好的催化性能.结合多种表征结果发现,催化剂CO氧化性能与其表面氧空位和Cu+–CO浓度紧密相关,提出了CuO/CeO2催化剂在CO氧化反应中可能的协同作用机制.

A series of CuO/CeO2 catalysts were prepared by solid state impregnation（SSI） and wet impregna‐tion（WI） methods and characterized by X‐ray diffraction, H2 temperature‐programmed reduction（H2‐TPR）, laser Raman spectroscopy（LRS）, in situ diffuse reflectance infrared Fourier transform spectroscopy（in situ DRIFTS）, and X‐ray photoelectron spectroscopy（XPS）. XPS and H2‐TPR results showed that SSI increased the dispersion of the copper species on the catalyst surface, which bene‐fited the reduction of CuO species. LRS results indicated that a higher concentration of oxygen va‐cancies was obtained by the SSI method unlike the WI method. CO oxidation results showed that at a given CuO loading, the activity of the catalysts prepared by SSI was higher than that of their coun‐terparts prepared by WI. Based on the combined characterization results, it was suggested that the enhanced activity was closely related to the higher concentrations of oxygen vacancies and Cu^＋‐CO species on the catalysts. Last, a possible synergetic mechanism was proposed for CO oxidation over the CuO/CeO2 catalysts.