贵金属纳米簇及负载物的可控制备及应用

发布时间：2018-01-26 19:27

本文关键词： 贵金属纳米材料载体 Au催化选择性加氢　出处：《吉林化工学院》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,贵金属纳米材料的制备及其在催化领域的研究越来越引起人们的广泛关注。但是,由于贵金属催化剂在制备方法、生产成本等方面的局限性,一定程度上限制了其大规模的商品化应用。未解决上述问题,本论文以贵金属纳米粒子的可控合成及其催化反应性能研究为主要内容进行了研究,主要包括以下几个部分:以水或乙醇作为溶剂,以PVA、PVP、十二烷基硫醇等作为保护剂,在NaBH_4或其它还原剂(如氨基硼烷、H_2等)作用下,得到均匀分散的Au纳米簇或更大尺寸的金纳米颗粒,颗粒尺寸可以在0.7-5nm范围内进行调节。将该制备方法扩展到Pd、Pt、Ag等纳米簇以及Au-Ag合金纳米簇的可控制备中。采用PVP作为保护剂,乙醇作为溶剂,NaBH_4作为还原剂制备胶体Au粒子,然后将其负载到γ-Al_2O_3、ZnO、ZSM-5分子筛等载体上。在450°C焙烧6小时后,颗粒尺寸依然小于2nm。采用相同方法制备的Pd-Sn/TiO_2复合材料,在300°C焙烧后颗粒尺寸仍保持在1.3nm。将Au纳米粒子合成过程与分子筛合成过程相结合,探索了原位法合成Au/分子筛材料。制备的Au/MTS-1、Au/MCM-41、Au/MCM-48复合材料500°C高温焙烧后,颗粒尺寸保持在2nm,表现出较好的稳定性。XRD与TEM的表征结果显示,Au纳米颗粒的引入未对分子筛的有序结构造成破坏。在肉桂醛选择性加氢反应中,纳米Au催化剂在肉桂醇选择性上展示了显著的差别。Au/Ni_2O_3表现出较好的C=C加氢能力,选择性生成苯丙醛,选择性为86%;催化剂Au/γ-Al_2O_3表现出较好的C=O加氢能力,选择性生成肉桂醇,选择性为67%。NH3-TPD和CO_2-TPD等表征结果显示肉桂醇选择性主要取决于纳米Au催化剂的酸碱性。催化剂Au/γ-Al_2O_3同时拥有酸中心和碱中心,酸碱中心间协同作用使得C=O双键优先吸附、活化和加氢,从而实现高的肉桂醇选择性。
[Abstract]:In recent years, more and more attention has been paid to the preparation of noble metal nanomaterials and their research in the field of catalysis. However, due to the limitations of noble metal catalysts in preparation methods, production costs and so on. To some extent, the large-scale commercial application of noble metal nanoparticles has been limited. However, the above problems have not been solved. In this paper, the controllable synthesis of noble metal nanoparticles and their catalytic properties are the main contents of the study. Mainly include the following parts: water or ethanol as a solvent, PVA, PVP, 12 alkyl mercaptan as protective agent in NaBH_4 or other reductants (such as aminoborane). Under the action of H2 and so on, the au nanoclusters or larger gold nanoparticles with uniform dispersion can be obtained. The size of au nanoparticles can be adjusted in the range of 0.7-5nm, and the preparation method is extended to PdPb-Pt. In the controllable preparation of Ag and Au-Ag alloy nanoclusters, colloidal au particles were prepared by using PVP as protective agent and ethanol as solvent NaBH4 as reducing agent. Then it was loaded on 纬 -Al2O3ZnOOZSM-5 molecular sieve carrier and calcined at 450 掳C for 6 hours. The particle size is still less than 2 nm. The Pd-Sn/TiO_2 composite is prepared by the same method. The particle size was kept at 1.3 nm after calcination at 300 掳C. the synthesis process of au nanoparticles was combined with the synthesis process of molecular sieve. Au- / molecular sieve materials were synthesized by in-situ method and calcined at 500 掳C after calcination of Au/ MCM-41 / MCM-41U / MCM-48 composite materials. The particle size remained at 2 nm, showing good stability. XRD and TEM characterization results showed. The introduction of au nanoparticles did not destroy the ordered structure of molecular sieve. The nanometer au catalyst showed remarkable difference in the selectivity of cinnamyl alcohol. Au/ Ni2O3 showed a better hydrogenation ability of Con C, and the selectivity was 86% for phenylpropanal. The catalyst au / 纬 -Al _ 2O _ 3 showed better hydrogenation ability and selectivity to cinnamol. The selectivity of cinnamol was determined by the acidity and alkalinity of au / 纬 -Al _ 2O _ 3 catalyst, and the results showed that the selectivity of cinnamyl alcohol was mainly determined by the acidity and basicity of au / 纬 -Al _ 2O _ 3 catalyst. Has acid and base centers. The synergistic action between acid-base centers leads to the preferential adsorption, activation and hydrogenation of Con O double bonds, thus achieving high selectivity of cinnamol.
【学位授予单位】：吉林化工学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O643.36

【相似文献】