ZrO4/SiO2-Al2O3催化肉桂醛MPV转移加氢性能

以九水合硝酸铝（Al（NO₃）₃·9H₂O）与正硅酸乙酯（TEOS）为前驱盐，采用溶胶-凝胶法制备一系列不同Al₂O₃含量的SiO₂-Al₂O₃复合氧化物，并通过浸渍硝酸氧锆引入ZrO₂，制备ZrO₂/SiO₂-Al₂O₃复合氧化物催化剂，考察催化剂在肉桂醛（CAL）MPV转移加氢中的催化性能，并结合N₂物理吸附、X射线粉末衍射（XRD）、傅里叶变换红外光谱（FTIR）、NH₃-程度升温脱附（NH₃-TPD）、Py-原位红外（Py-IR）等技术，研究催化剂结构、织构以及表面性质与其催化性能间的构效关系.研究表明，所制备的催化剂均以L酸为主，并含有少量B酸中心，这使得加氢产物以肉桂醇（COL）为主，并含有少量1-苯丙烯-2-丙基醚（CPE）.Al₂O₃含量不仅影响催化剂表面的酸中心数量，而且对催化剂的织构参数有较大影响.随Al₂O₃含量的增加，催化剂表面L酸与B酸中心均有所增加，而孔径则持续变小，这使得催化反应呈现CAL转化率先增加后减少、目标产物COL选择性先稍有减小后有所增加的趋势.在Si/Al比为2时，催化剂具有最优的催化性能，优化反应条件下，CAL转化率达96%，目标产物COL选择性达90%.

Catalytic MPV Transfer Hydrogenation Performance of Cinnamaldehyde over ZrO4/SiO2-Al2O3

SiO₂-Al₂O₃ composite oxides with different Al₂O₃ content has been synthesized via sol-gel procedures by using Al(NO₃)₃·9H₂O and TEOS as precursors. Then ZrO₂ was introduced by wetness impregnation method to prepared ZrO₂/SiO₂-Al₂O₃ composite oxides catalysts. The structure-activity relationship of the catalytic MPV transfer hydrogenation of cinnamaldehyde over ZrO₄/SiO₂-Al₂O₃ was investigated by N₂ adsorption, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, temperature programmed desorption of NH₃ (NH₃-TPD), and FTIR spectroscopy of adsorbed Pyridine (Py-IR). The experimental results indicated that the hydrogenation products were mainly cinnamyl alcohol (COL) and a small amount of 1-phenylpropyl-2-propyl ether (CPE) because of the dominant Lewis acid sites and few Bronsted acid sites presented in all catalysts. The Lewis acid sites and Bronsted acid sites both increased as the increase of Al₂O₃ content, while the pore diameters continuously decreased, which result in the increase of CAL conversation at first and then decrease, and result in the decrease of COL selectivity at first and then increase. At Si/Al ratio of 2, the catalyst has the best catalytic performance. Under the optimum reaction conditions, the conversion of CAL reaches 96%, and the selectivity of COL is about 90%.