研究了不同Au/Pd摩尔比的AuPd/CeO2双金属催化剂在苯甲醇氧化制苯甲酸及其钠盐反应中的催化活性,利用XRD, UV-Vis DRS, TEM和XPS等手段对催化剂的结构进行了系统考察。结果表明, Au-Pd纳米颗粒以合金形式分散在CeO2载体上,不同Au/Pd摩尔比会影响催化剂表面活性物种的粒径大小和尺寸分布,并改变催化剂表面物种的组成。 Au-Pd之间的电子效应和协同效应显著影响其催化活性。当Au/Pd摩尔比为3时催化剂表现出最好的催化活性,苯甲酸产率可达92%。此外,双金属催化剂的催化活性显著优于单金属催化剂,主要归因于Au和Pd之间的协同效应。 AuPd/CeO2催化剂还具有良好的稳定性, Au/Pd摩尔比为3的AuPd/CeO2催化剂使用7次后仍然具有较高的催化活性。
A series of AuPd/CeO2 bimetallic catalysts with different Au/Pd molar ratios were investigated and their catalytic performance in the oxidation of benzyl alcohol to sodium benzoate and benzoic acid under solvent-free conditions was studied. The supported catalysts were characterized by X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The Au-Pd nanoparticles were successfully deposited onto CeO2 as a homogeneous alloy. The activity of the bimetallic catalysts was superior to that of the corresponding monometallic catalysts. This improvement was attributed to the synergistic effect between Au and Pd. The catalyst with an Au/Pd molar ratio of 3/1 showed the best catalytic performance (the yield of benzoic acid reached 92%), and it could be easily recovered and reused for more than seven successive reactions without significant loss of activity.