【摘要】 用XPS和XAES（X光激发歇电子能谱）研究了Pt/ZnO催化剂的金属与担体间的相互作用。X射线照射、真空加热、尤其是不同温度下的H₂处理都能不同程度地使 ZnO还原,而担载Pt原子簇的存在明显地促进了ZnO的还原;实验结果表明:由H₂处理引起的Pt与ZnO间的相互作用在较宽温度范围内经历两个不同的阶段:低温氢处理（室温和 150℃）使Pt4f电子结合能产生负化学位移,表明电荷从部分还原的担体转移给了担载的金属Pt原子;而高温（300℃）则引起担载金属与担体间界面原子重排,只有经过400℃空气氧化才会破坏这种作用,使体系恢复到初始状态。更多还原

【Abstract】 The interaction between Pt and ZnO support of Pt/ZnO catalyst was studied by means of photoelectron spectroscopy. It was found that the binding energy of Zn2p electron was not sensitive to the valence states of zinc atom, so binding energies of Pt4f XPS and ZnLMM(344) XAES were examined.X-ray irradiation, vacuum heating and especially H2 treatment at different temperatures would effect the reduction to varying degrees on ZnO and Pt/ZnO. A ZnLMM(344) shoulder peak revealed the appearance of lower valence zinc. Pt/ZnO as a whole entity is remarkably susceptible to hydrogen. Lower valence Zn as well as negatively charged Pt could be noticeably detected on samples subjected, to hydrogen even at room temperature. Charge transfer from reduced Zn to Pt was assumed at ambient temperature. It implied that metal-support interaction was effected since the moment of Pt deposition on ZnO.However, such valence shift realized at room temperature was partly reversible by merely exposure to atmosphere. In contrast with this, for samples treated in hydrogen at elevated temperature, more distinguished and irreversible result happened so that the peak shift of Pt4f XPS and ZnLMM(344) XAES could be restored only after oxidation in air above 400℃. It demonstrated the occurrence of a stronger state of Pt-ZnO interaction.Thus, it was verified that the metal support interaction of Pt/ZnO catalyst in fact developed in different stages during hydrogen treatment in wide temperature range.更多还原