在竞争性化中的选择性:单位催化剂···酸氧化物表面结合几何学的影响
Weixing Gu1, Madelyn Marie Stalzer1, Christopher P Nicholas2
1†Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
Journal of the American Chemical Society
|April 18, 2015
概括
在酸性氧化物上的有机基催化剂有效化. 催化剂的活性和选择性取决于表面酸度和硬质量,为从汽油中去除提供了洞察力.
科学领域:
- 不同质的催化剂.
- 有机金属化学 有机金属化学
- 表面科学是一门科学.
背景情况:
- 化是从汽油中去除致癌的关键.
- 在酸性氧化物上支持的Organozirconium复合物显示出作为催化剂的希望.
- 了解结构-活动关系是优化催化剂性能的关键.
研究的目的:
- 为了研究素化中的有机基催化剂的活性和选择性.
- 探索支酸度和催化剂固体质量对催化性能的影响.
- 用光谱和计算方法阐明烯化机制.
主要方法:
- 在布伦斯特德酸氧化物 (硫酸ZrO2,硫酸Al2O3,ZrO2-WO3) 上,有机氧化物复合物 (Cp*ZrMe3,Cp*ZrBz3,Cp*ZrPh3) 的化学吸收.
- 在温和条件下 (25°C,1 atm H2) 使用/混合物的化反应.
- 使用固态NMR光谱,X射线吸收光谱 (XAS) 和周期密度函数理论 (DFT) 计算进行了表征.
主要成果:
- 催化剂活性与支的布伦斯特德酸度正相关 (ZrS > AlS ≈ ZrW).
- 素化选择性受到催化剂结构和固体阻碍的影响,其中Cp*ZrBz3/ZrS具有高活性和中等选择性.
- 在有机基催化剂中的庞大的基团扩大了金属支距离,削弱了离子配对,并使硬质负载的激活.
结论:
- 支的Bronsted酸度在增强基催化剂活性中起着关键作用,用于化.
- 固态因素,特别是上配体群的大小,显著影响化速率和选择性.
- 这些发现为设计有效的催化剂提供了有价值的见解,用于从燃料流中选择性去除.
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