覆盖对催化乙酸乙烯合成的影响:理论与实验之间的比较
Florencia Calaza1, Dario Stacchiola, Matthew Neurock
1Department of Chemistry and Biochemistry, and Laboratory for Surface Studies, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA.
表面覆盖面显著影响异质催化. 这项关于乙烯乙氧化对的研究揭示了反应通过萨马诺斯机制进行,具有限制速率的β-化物消除步骤.
科学领域:
- 不同质的催化剂.
- 表面化学 表面化学
- 反应动力学反应动力学
背景情况:
- 表面覆盖在异质催化中至关重要,影响反应通路和动力学.
- 理论和实验研究往往忽视了吸附剂覆盖对催化反应的影响.
- 了解覆盖效应对于优化催化剂性能至关重要.
研究的目的:
- 调查表面覆盖面对乙烯乙氧化对Pd的影响.
- 为了阐明反应机制,并确定在高覆盖条件下速度限制的步骤.
- 结合理论计算与实验数据进行综合分析.
主要方法:
- 第一个原则密度函数理论 (DFT) 计算.
- 在精确定义的Pd(111) 表面上进行实验性表面定位研究.
- 动力测量以确定实验激活障碍.
主要成果:
- 反应通过在酸盐和的Pd{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{\displaystyle Pd}{11}}表面上通过萨马诺斯机制进行.
- 速度限制的步骤被确定为从吸附的乙基乙烯中间体中消除β-化物.
- 计算的激活障碍 (53 kJ/mol) 与实验值 (55 ± 4 kJ/mol) 非常接近.
结论:
- 表面覆盖在确定乙烯乙氧化反应途径方面发挥着关键作用.
- 在高吸附剂覆盖条件下,萨马诺斯机制更受欢迎.
- 这项研究提供了对酸乙烯合成与催化剂的详细机制理解.
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