酸性离子液体中铂纳米粒子的制备、表征及应用

Preparation,Characterization and Application of Platinum Nanoparticles in Acidic Ionic Liquid

基于功能化离子液体的特性,开发出不使用聚合物保护剂制备铂纳米粒子并同时获得具有金属和酸活性中心双功能催化剂的新方法。首先,设计并合成出了一种新型季铵型质子(Br觟nsted)酸性离子液体(N,N,N-三甲基-N-磺丁基硫酸氢铵([HSO3-b-N(CH3)3]HSO4)),然后,利用化学还原方法在该离子液体中制备了金属铂纳米粒子,并采用紫外光谱、傅立叶红外光谱、X-光电子能谱、透射电子显微镜和X射线衍射等方法对所制备的金属铂纳米粒子进行了结构表征。结果表明,所制备的铂纳米粒子具有面心立方结构,离子液体作为修饰剂修饰在铂纳米粒子的表面,有效地阻止了铂纳米粒子的团聚;将该含有铂纳米粒子的酸性离子液体作为双功能催化剂,直接用于硝基苯加氢合成对氨基苯酚反应,发现其具有良好的催化性能,在85℃、4h、0.4MPa条件下,硝基苯转化率为98.6%,对氨基苯酚收率为75.8%,回收的酸性离子液体纳米铂双功能催化体系中铂纳米粒子依然具有很好的分散性和稳定性。

Based on the characteristics of ionic liquid, platinum nanoparticles were prepared without using polymer as protecting agent, and a bifunctional catalyst with metallic and acidic active sites was prepared simultaneously. Firstly, a quaternary ammonium type of Bronsted acidic ionic liquid （N,N,N-trimethyl-N-sulfobutyl hydrogen sulfate （[HSO3-b-N（CH3）3]HSO4）） was designed and synthesized. Then, platinum nanoparticles were prepared in this ionic liquid. UV-Vis, FTIR, XPS, HRTEM and XRD were used to characterize the nanoparticles. The results show that the platinum nanoparticles are with a face-centered cubic structure and good stability because the aggregation is effectively prevented by the surface modification of the ionic liquid. When the ionic liquid containing platinum nanoparticles is used as a bifunctional catalyst for the hydrogenation of nitrobenzene to p-aminophenol, it shows a good catalytic activity. The nitrobenzene conversion and p-aminophenol yield is 98.6% and 75.8%, respectively, for the reaction conditions of 85 ℃, 0.4 MPa and 4 h. In addition, platinum nanoparticles still show a good dispersion and stability in the recovered bifunctional catalyst.