Metal catalyzed ethylene epoxidation:A comparative density functional theory study

作     者：Ruipeng Ren Yongkang Lu Xianyong Pang Guichang Wang 

作者机构：College of Chemistry and Chemical Engineering Taiyuan University of Technology Taiyuan 030024 Shanxi China Key Laboratory of Coal Science and Technology Ministry of Education and Shanxi Province Taiyuan University of TechnologyTaiyuan 030024 Shanxi China Department of Chemistry Nankai University Tianjin 300071 China 

出 版 物：《Journal of Natural Gas Chemistry》 (天然气化学杂志（英文版）)

年 卷 期：2011年第20卷第3期

页      面：303-310页

核心收录：

学科分类：081702[工学-化学工艺] 0808[工学-电气工程] 081704[工学-应用化学] 07[理学] 0817[工学-化学工程与技术] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0807[工学-动力工程及工程热物理] 0703[理学-化学] 

主　　题：ethylene epoxidation metal surface DFT calculation activity selectivity 

摘      要：Ethylene epoxidation on Ag（111）, Pt（111）, Rh（111） and Mo（100） has been studied by density functional theory （DFT） calculations. The results show that the adsorption energies of possible adsorbed species involved in the ethylene epoxidation increase in the order： Ag〈Pt〈Rh〈Mo, and the activation energies of the formation of epoxide （EtO） and acetaldehyde （Ac） follow the same order. Moreover, it is found that the smallest difference in the activation energies between EtO formation and Ac formation is shown on Ag. These results indicate that the metallic Ag shows the highest between activity and selectivity for ethylene epoxidation among the studied metal surfaces. Perhaps, the stability of OMME intermediate is the crucial factor in controlling the activity and selectivity. And the stronger the binding of OMME, the lower the activity and selectivity are. In addition, the relationships between the reaction enthalpy and activation energy on these four metal surfaces are investigated, and it is found that such a correlation is only applied for OMME（a） → EtO（a） and OMME（a） → Ac（a）, while invalid for the case of C2H4（a） ＋ O（a） → OMME（a）.