电解银表面氧物种转化的原位拉曼光谱表征  

Transformation of Various Oxygen Species on the Surface of Electrolytic Silver Characterized by in Situ Raman Spectroscopy

作　　者：任丽萍[1] 戴维林[1] 杨新丽[1] 曹勇[1] 谢在库[2] 范康年[1] 

机构地区：[1]复旦大学化学系上海市分子催化与功能材料重点实验室,上海200433 [2]中国石油化工股份有限公司上海石油化工研究院,上海201208

出　　处：《催化学报》2006年第2期115-118,共4页

基　　金：国家自然科学基金(20407006;20573024);上海市科委基础研究重点项目(02DJ14021)资助

摘　　要：首次采用原位共焦显微激光拉曼光谱研究了经纯氧预处理后电解银表面吸附的不同氧物种在升温过程中相互转化的情况.结果发现,当温度低于423 K时,AG-O2物种缓慢转化为超氧物种AG[O-O]-;温度升高至423 K时,AG[O-O]-物种将随着时间的延长转化为AG-O(Α)物种;继续升高温度,AG-O(Α)物种首先转化为AG-O-O-AG物种,再进一步转化为电解银表面最稳定的AG-O(Γ)次表层氧物种并保持至973 K以上.结合实际反应体系,低温下电解银表面吸附的氧物种主要是分子氧,在类似乙烯环氧化反应的条件下这些分子氧将转化成AG-O(Α)物种,而在类似甲醇选择氧化制甲醛的反应条件下又转化为在高温下较稳定的AG-O(Γ)物种,根据具体的转化细节推测了可能的机理.Transformation of various oxygen species adsorbed on electrolytic silver surface pretreated by pure oxygen at 423-973 K under ambient pressure was observed for the first time by in situ confocal microprobe Raman spectroscopy. Ag-O2 species can transform into Ag[O-O]^- species slowly at temperatures below 423 K. Once the temperature rises to 423 K, the transformation of Ag[O-O]^- to Ag-O（α） species takes place. With further increase of temperature, Ag-O（α） species first transforms to Ag-O-O-Ag and then to Ag-O（γ） species which is the most stable oxygen species on the silver surface and can be maintained even above 973 K. As for the practical reaction system, the adsorbed molecular oxygen was found to be present on the silver surface at low temperature. It transforms to Ag-O（α） species under similar conditions as those for the partial epoxidation of ethylene, and then transforms to Ag-O（γ） oxygen Species under conditions similar to those for selective oxidation of methanol to formaldehyde. A possible mechanism for the detailed transformation of oxygen species was also proposed.

关 键 词：电解银 氧物种 原位拉曼光谱 

分 类 号：O643.3[理学—物理化学]