可控粒径纳米Rh的液相还原法制备及其在甲醇重整制氢反应中的应用

高等学校化学学报 ›› 2005, Vol. 26 ›› Issue (3): 480.

可控粒径纳米Rh的液相还原法制备及其在甲醇重整制氢反应中的应用

钱玲, 吕功煊

中国科学院兰州化学物理研究所, 羰基合成与催化氧化国家重点实验室兰州 730000

收稿日期:2004-07-30 出版日期:2005-03-10 发布日期:2005-03-10
通讯作者: 吕功煊(1964年出生),男,研究员,博士生导师,主要从事多相催化研究.E-mail:gxlu@ns.lzb.ac.cn E-mail:gxlu@ns.lzb.ac.cn
基金资助:
国家重点基础研究发展规划项目(批准号:G20000264)资助

Synthesis of Size-controlled Rh Nanoparticles with Liquid-phase Reduction Method and Its Application in Preparation of Hydrogen via Steam Reforming of Methanol

QIAN Ling, LV Gong-Xuan

State Key Laboratory for Oxo catalytic and Catalytic Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China

Received:2004-07-30 Online:2005-03-10 Published:2005-03-10

摘要/Abstract

摘要： 采用液相还原法,通过控制溶液的pH值制备了一系列粒径可控的纳米Rh金属粒子,并用TEM和UV-Vis等技术对其进行了表征.结果表明,在不同pH值的还原溶液中得到的贵金属粒径有明显变化.溶液碱性越强,还原所得金属纳米粒子的粒径越小.当溶液pH值为13时,纳米Rh粒径最小,为6nm左右.采用浸渍法将得到的纳米粒子负载于γ-Al₂O₃上,以甲醇重整制氢为探针反应,考察了负载型Rh/γ-Al₂O₃中Rh粒子粒径与反应活性的关系,发现随纳米Rh粒径的减小,反应转化率与氢气选择性都有明显提高.由此可以推测,纳米粒子的尺寸效应是Rh/γ-Al₂O₃在重整反应中具有高活性的重要原因.

关键词: 纳米粒子, Rh/&gamma, -Al₂O₃, pH值, 甲醇重整

Abstract: Development of nanoparticles with well-defined size is an important aspect of nanotechnology. A simple method for preparing size-controlled Rh nanoparticles was developed on the basis of chemical reduction of RhCl₃·3H₂O with nitromethane. Adjusting pH of the solution is necessary in this method. Transmission electron microscopy and UV-Vis absorption were used to study the structure and behavior of the nanoparticles as a function of pH. The results show that pH value is critical determinant for the nanoparticles size in solution, in the case of pH=7, 9 and 11, the average size is 50, 30 and 13 nm, respectively, and with the increase of pH, the size of nanoparticles becomes smaller. As pH in solution is 13, the Rh nanoparticles is the smallest, with a particle size about 6 nm. The nanoparticles were supported on γ-Al₂O₃ by impregnation method. The activity for methanol steam reforming was investigated. The result indicates that the size of the nanoparticles strongly influences the activity and selectivity of steam reforming of methanol. Both conversions and selectivities are dependent on the particle size of Rh. When the nanoparticles become smaller, the activity of reactivity is improved obviously.

Key words: Nanoparticles, Rh/γ-Al₂O₃, pH value, Steam reforming of methanol

中图分类号:

O643.3

TrendMD:

钱玲, 吕功煊. 可控粒径纳米Rh的液相还原法制备及其在甲醇重整制氢反应中的应用. 高等学校化学学报, 2005, 26(3): 480.

QIAN Ling, LV Gong-Xuan . Synthesis of Size-controlled Rh Nanoparticles with Liquid-phase Reduction Method and Its Application in Preparation of Hydrogen via Steam Reforming of Methanol. Chem. J. Chinese Universities, 2005, 26(3): 480.

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