化工学报 ›› 2019, Vol. 70 ›› Issue (10): 3967-3975.DOI: 10.11949/0438-1157.20190480

• 催化、动力学与反应器 • 上一篇    下一篇

Ag表面乙醇选择性催化氧化的密度泛函理论研究

徐新潮(),田鹏飞,徐晶(),韩一帆   

  1. 华东理工大学化学工程联合国家重点实验室,上海 200237
  • 收稿日期:2019-05-07 修回日期:2019-08-14 出版日期:2019-10-05 发布日期:2019-10-05
  • 通讯作者: 徐晶
  • 作者简介:徐新潮(1988—),男,博士研究生,xinchao.xu@gmail.com
  • 基金资助:
    国家重点研发计划项目(2018YFB0605803)

Density functional study of selective oxidation of ethanol over silver catalysts

Xinchao XU(),Pengfei TIAN,Jing XU(),Yifan HAN   

  1. State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2019-05-07 Revised:2019-08-14 Online:2019-10-05 Published:2019-10-05
  • Contact: Jing XU

摘要:

采用密度泛函理论计算对Ag(111)和Ag(211)表面乙醇催化氧化过程进行了系统性研究。研究发现原子氧物种是常温下乙醇氧化的关键中间体。在表面原子氧物种辅助下,乙醇O—H键和α-C—H键依次断裂,生成乙氧基中间体和乙醛产物(活化能(E a)<38.0 kJ/mol)。乙醛随后与表面原子氧和羟基氧物种作用,导致CCOO(在Ag(111)表面发生CCOO C+ CO2)和CH2COO(在Ag(211)表面发生CH2COO CH2+ CO2)中间体C—C键断裂生成CO2,该过程是速率控制步骤(E a>95.5 kJ/mol)。计算结果表明乙醇在Ag表面催化氧化过程为结构敏感反应,降低表面缺陷位数量可提高产物中乙醛选择性。

关键词: 分子模拟, 银, 催化, 部分氧化

Abstract:

A systematic study on the catalytic oxidation of Ag(111) and Ag(211) on the surface of Ag(111) was carried out by density functional theory. It was found that atomic O* is necessary to initiate the reaction at the ambient conditions. The O—H bond in the ethanol is activated with the help of adsorbed atomic O* to form ethoxy, which then further transfers hydrogen in α-C—H to adsorbed O* forming the acetaldehyde (E a<38 kJ/mol), which, in turn, reacts with atomic O*/OH* to form final product CO2. To generate CO2, C—C bond breaking (CCOO C+ CO2 on Ag(111) and CH2COO CH2+ CO2 on Ag(211)) exhibits the highest barriers (E a>95.5 kJ/mol), which indicated it is the rate-determining step. The results indicate that the catalytic oxidation of ethanol on silver surfaces is structural sensitive. Selectivity towards value-added products like acetaldehyde would be improved by reducing the density of defected sites.

Key words: molecular simulation, silver, catalysis, partial oxidation

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