关于Cs在Ag上的乙烯环氧化中促进Cs的机制
1Department of Chemical Engineering, University of Delaware, Newark, DE 19716, USA. linic@fhi-berlin.mpg.de
Journal of the American Chemical Society
|July 1, 2004
概括
(Cs) 提高了对白银催化剂的乙烯环氧化选择性. 它稳定了燃烧过程中所需的乙烯氧化物 (EO) 形成途径,提高了催化剂的性能.
科学领域:
- 表面科学是一门科学.
- 不同质的催化剂.
- 化学反应机制的化学反应机制
背景情况:
- 银催化剂对于乙烯环氧化,一个关键的工业过程至关重要.
- 了解促进剂效应对于优化催化剂选择性至关重要.
- (Cs) 已知会影响银催化剂的性能.
研究的目的:
- 阐明 (Cs) 影响银表面乙烯环氧化选择性的机制.
- 分析促进体-中间体和促进体-过渡状态的相互作用.
- 确定Cs如何改变竞争反应路径的能量格局.
主要方法:
- 理论检查促进体-中间体和促进体-过渡状态相互作用.
- 对吸附的Cs在Ag111) 表面上产生的电子效应的分析.
- 过渡状态稳定性的计算建模.
主要成果:
- (Cs) 增加了对乙烯氧化物 (EO) 形成的选择性.
- Cs比燃烧的过渡状态更稳定了EO形成的过渡状态.
- 吸附的Cs通过双极/双极相互作用在Ag上诱导显著的电场.
- 选择性路径的过渡状态与燃烧路径的过渡状态相比,呈现出更有利的双极方向.
结论:
- 通过选择性地稳定导致乙烯氧化物的过渡状态而起促进作用.
- 银表面上由Cs产生的电场是调节反应选择性的关键.
- 这项工作为异质催化中的促进子功能提供了基本的见解.
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