负载型Pt@Pd纳米粒子的制备与催化性能研究

摘要

Using self-made poly (N-vinylacetamide ) ( PNVA ) grafted polyacrylonitrile/polystyrene (PNVA-g-PAN/PSt) microspheres as matrix, H2PtCl6 as the metal source, ethanol as reducing agent, platinum nanoparticles were located onto surfaces of the PNVA-g-PAN/PSt microspheres by in-situ reduction method.Palladium ions were then reduced on the surfaces of platinum nanoparticles to form Pt@ Pd nanoparticles.The shape and size of Pt@ Pd nanoparticles were characterized by TEM.The results shows that reduced Pt@ Pd nanoparticles were dispersed evenly on surfaces of the PNVA-g-PAN/PSt micro-spheres.The average size of the loaded Pt@ Pd nanoparticles has a change that increases then decreases through increasing ratio of H2PtCl6 to PdCl2 based on the analysis of TEM and X-ray diffraction.It was found that the average size was about 9 ～22.2 nm.Furthermore,the catalytic activity of this loaded Pt@ Pd nanoparticles for the cross-coupling reaction of iodobenzene with acrylic acid was good, which can be known from the yield measurement of cinnamic acid.%用聚N-乙烯基乙酰胺接枝聚丙烯腈/聚苯乙烯(PNVA-g-PAN/PSt)聚合物微球为载体,H<,2>PtCl<,6>为金属源,无水乙醇为还原剂,将配位的Pt<'4+>离子原位还原成为Pt纳米粒子负载于PNVA-g-PAN/PSt微球表面,进而在Pt纳米粒子上将Pd<'2+>还原,制备r负载型Pt@Pd纳米粒子.用透射电子显微镜(TEM)对所制负载型Pt@Pd纳米粒子的形态与尺寸大小进行表征,结果显示,Pt@Pd纳米粒子均匀分布在聚合物微球表面;TEM和X-射线衍射结果显示,Pt@Pd纳米粒子的平均粒径随H<,2>PtCl<,6>与PdCl<,2>比例的增加出现先增大后减小的变化趋势,粒径在9～22.2 nm之间;对肉桂酸产率的测定结果显示,该负载型Pt@Pd纳米粒子对碘代苯与丙烯酸交叉偶联反应有良好催化活性.