State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Chemistry. 2011 Jan 24;17(4):1247-56. doi: 10.1002/chem.201002469. Epub 2010 Dec 10.
Gold nanoparticles with uniform mean sizes (≈3 nm) 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 β-C-H bond of alcohol, which requires the coordinatively unsaturated Au atoms, is the rate-determining step.
负载在各种载体上的具有均匀平均粒径（≈3nm）的金纳米颗粒已被制备并研究用于无氧化剂条件下苄醇氧化脱氢为苯甲醛和氢气。水滑石（HT）具有强酸性和强碱性，提供了最佳的催化性能。通过在控制条件下的沉积-沉淀法成功制备了具有各种平均金颗粒尺寸（2.1-21nm）的 Au/HT 催化剂。对这些催化剂的详细催化反应研究表明，Au 催化的苄醇脱氢是一个结构敏感的反应。随着 Au 平均粒径（从 12nm 减小到 2.1nm）的减小，TOF 增加。当平均 Au 粒径小于 4nm 时，TOF 急剧上升。我们目前的工作表明，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。提出了一个反应机理来合理化这些结果。假设醇的β-C-H 键的活化，这需要配位不饱和的 Au 原子，是速率决定步骤。
