Au/TiO2催化剂制备条件对巴豆醛选择加氢的影响

采用沉积-沉淀法制备了纳米Au/TiO2催化剂, 以X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)等手段对催化剂进行了系统的表征, 并考察了该催化剂在巴豆醛液相加氢制巴豆醇反应中的催化性能. 通过改变活化气氛、负载量和还原温度, 能够调节Au粒子的尺寸及金属与载体间的相互作用. 在673 K还原条件下制备Au质量分数为9.2%的Au/TiO2 催化剂上, Au粒子的平均粒径为2 nm, 初始加氢速率达到13.7×10-5 mol·s-1·g-1, 同时巴豆醇最高收率可达69.9%. 结合表征结果, 该催化剂良好的巴豆醛选择加氢性能归属为载体TiO2在还原条件下产生的氧缺陷位对Au纳米粒子的锚定作用及给电子作用.

Influence of Au/TiO2 Catalyst Preparation Parameters on the Selective Hydrogenation of Crotonaldehyde

Nanosized Au/TiO2 catalysts were prepared by the deposition-precipitation method. These catalysts were evaluated by a liquid phase hydrogenation of crotonaldehyde to crotyl alcohol and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). By changing the activation atmosphere, the Au loading, and the reduction temperature we found that the dimension of the Au particles and the metal-support interaction were readily adjustable. For the Au/TiO2 catalyst reduced at 673 K with an optimal Au mass fraction of 9.2%, the mean particle size of Au was 2 nm and the initial hydrogenation rate was as high as 13.7×10-5 mol·s-1·g-1, while the maximum yield of crotyl alcohol was 69.9%. Combined with the characterization results, the superior performance of this catalyst was attributed to it having an optimal size and to its electronic modification effects on the Au nanoparticles. This was due to oxygen defects generated on the TiO2 during the reduction process.