Hydrotalcite-Supported Gold Catalyst for the Oxidant-Free Dehydrogenation of Benzyl Alcohol: Studies on Support and Gold Size Effects
Hydrotalcite-Supported Gold Catalyst for the Oxidant-Free Dehydrogenation of Benzyl Alcohol: Studies on Support and Gold Size Effects
复制标题
用于苯甲醇无氧化剂脱氢的水滑石负载金催化剂：负载和金尺寸效应的研究
DOI：
10.1002/chem.201002469
复制
发表时间：
2011-01-01
影响因子：
4.3
通讯作者：
Wang, Ye
中科院分区：
文献类型：
--
作者：
Fang, Wenhao;Chen, Jiashu;Wang, Ye
制备了平均粒径约为3 nm的金纳米粒子负载于不同载体上，并研究了其在苯甲醇无氧化脱氢反应中的催化性能。同时具有强酸性和强碱性的水滑石（HT）的使用提供了最佳的催化性能。采用沉积沉淀法在控制条件下成功地制备了不同平均Au粒径（2.1-21 nm）的Au/HT催化剂。详细的催化反应研究表明，金催化的苯甲醇脱氢反应是一个结构敏感的反应。周转频率（TOF）的增加而减少Au平均粒径（从12至2.1 nm）。当平均Au颗粒尺寸变得小于4 nm时，TOF急剧上升。我们的工作表明，载体的酸碱性质和Au纳米颗粒的尺寸是控制醇脱氢催化的两个关键因素。提出了一种反应机理来合理化这些结果。推测醇的β C-H键的活化是反应的速率控制步骤，而活化过程需要配位不饱和的Au原子。
Gold nanoparticles with uniform mean sizes (approximate to 3nm) loaded onto various supports have been prepared and studied for the oxidant-free dehydrogenation of benzyl alcohol to benzaldehyde and hydrogen. The use of hydrotalcite (HT), which possesses both strong acidity and strong basicity, provides the best catalytic performance. Au/HT catalysts with various mean Au particle sizes (2.1-21 nm) have been successfully prepared by a deposition precipitation method under controlled conditions. Detailed catalytic reaction studies with these catalysts demonstrate that the Au-catalyzed dehydrogenation of benzyl alcohol is a structure-sensitive reaction. The turnover frequency (TOF) increases with decreasing Au mean particle size (from 12 to 2.1 nm). A steep rise in TOF occurs when the mean Au particle size becomes smaller than 4 nm. Our present work suggests that the acid base properties of the support and the size of Au nanoparticles are two key factors controlling the alcohol dehydrogenation catalysis. A reaction mechanism is proposed to rationalize these results. It is assumed that the activation of the beta C-H bond of alcohol, which requires the coordinatively unsaturated Au atoms, is the rate-determining step.