负载型Pt@Pd纳米粒子的制备与催化性能研究

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,H2PtCl6为金属源,无水乙醇为还原剂,将配位的Pt4+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Pd2+还原,制备了负载型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H2PtCl6与PdCl2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。

Preparation of loaded Pt@ Pd nanoparticles and catalytic property

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 microspheres.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.