氧化淀粉均相还原制备纳米金及用于催化丙烯环氧化反应

发布时间：2018-01-25 13:44

本文关键词： 羧基淀粉纳米金催化剂丙烯环氧化催化　出处：《功能材料》2017年02期 　论文类型：期刊论文

【摘要】：以过氧化氢氧化淀粉制备水溶性羧基淀粉(OST),通过红外光谱、滴定法、粘度和水溶性测试表征OST结构与性能。选择溶解性最高、羧基含量42.1%OST(OST42.1)用于还原氯金酸获得纳米金颗粒,通过溶胶负载制备纳米金催化剂。利用紫外-可见光谱、透射电镜、X衍射和低温N_2物理吸附表征所制备的催化剂的微观结构与性能。结果表明,随着OST42.1浓度由5g/L上升40g/L时,纳米金颗粒直径呈先降低而上升的趋势,在20g/L时还原所得纳米金颗粒负载量和颗粒平均直径分别为0.5%和1.8nm,比表面积和容积率分别为353.01m~2/g和0.293cm~3/g。以20g/L的OST42.1制备的催化剂,用于催化丙烯环氧化反应,转化率、氢气效率和丙烯环氧化选择性分别达到18.5%,31.1%和68%。其原因在于OST42.1在水中具有溶解度高和粘度低等优点,以均相还原氯金酸能增加纳米金颗粒负载量及降低直径,提高丙烯气相环氧化效率。研究表明,高水溶性的羧基淀粉能有效还原氯金酸,获得高催化活性的纳米金颗粒,在丙烯气相环氧化领域中具有广泛的应用。
[Abstract]:Water soluble carboxyl starch was prepared by oxidizing starch with hydrogen peroxide. The structure and properties of OST were characterized by IR, titration, viscosity and water solubility tests. Carboxyl content 42.1 OST42.1) was used to reduce chlorgold acid to obtain gold nanoparticles, and the nanometer gold catalyst was prepared by sol-supported catalyst. UV-Vis spectrum and transmission electron microscope were used. The microstructure and properties of the catalysts were characterized by X-ray diffraction and physical adsorption at low temperature. The results show that with the concentration of OST42.1 increasing from 5 g / L to 40 g / L. The diameter of nanocrystalline gold particles decreased first and then increased. The loading amount and average diameter of gold nanoparticles reduced at 20g / L were 0.5% and 1.8 nm, respectively. The specific surface area and volume ratio were 353.01mg and 0.293cm / g, respectively. The catalyst prepared with 20g / L OST42.1 was used to catalyze the epoxidation of propylene. The conversion efficiency of hydrogen and the selectivity of propylene epoxidation reached 18.5% and 68% respectively. The reason is that OST42.1 has the advantages of high solubility and low viscosity in water. Homogeneous reduction of chlorgold acid can increase the loading amount and decrease the diameter of gold nanoparticles and improve the gas phase epoxidation efficiency of propylene. The study shows that the high water-soluble carboxylic starch can effectively reduce chloruronic acid. Gold nanoparticles with high catalytic activity are widely used in propylene gas phase epoxidation.
【作者单位】：华南理工大学机械与汽车工程学院;厦门大学化学化工学院;
【基金】：中央高校基本科研业务费重点资助项目(2015ZZ020) 广州市科技计划基础研究资助项目(2014J4100038)
【分类号】：TB383.1;O621.251
【正文快照】： 0引言环氧丙烷(propylene oxide,PO)是非常重要的基础化工原料,主要用于生产丙二醇、各种非离子表面活性剂等[1]。目前工业上主要采用氯醇法、共氧化法等生产环氧丙烷,其缺陷是会造成严重的环境污染。贵金属纳米材料因具有颗粒粒径小、比表面积大和催化活性高等优点,能应用于

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