碳化硅基双金属催化剂光催化呋喃化合物加氢开环的研究

The catalytic hydrogenolysis of furan and its derivatives to alcohols, acids and esters is one of key processes to produce fine chemicals from biomass. Pt, Pd and Ru are usually employed as catalysts for the hydrogenolysis of furan derivatives. However, many of these reactions are carried out under the condition of high temperature and high pressure to achieve high yield and efficiency, which greatly increase the energy consumption. Au nanoparticles exhibit strong visible light absorption due to the localized surface plasmon resonance (LSPR) effect. The conduction electrons in Au nanoparticles gain the irradiation energy to produce “hot” electrons with high energy concentrating at the surface, which is desirable for activating reactants adsorbed on the nanoparticles for chemical reactions. Therefore, incorporating Au into Pt, Pd or Ru to form bimetallic nanaoparticles can utilize visible light as energy source to enhance the hydrogenolysis of furan derivatives at mild conditions. Moreover, when n-type SiC is employed to support metal nanoparticles with higher work functions, there can form a metal-semiconductor contact (Mott-Schottky contact) between them. The photo-generated electrons can quickly transfer form SiC to metal nanoparticles and thus improve their catalytic activity. The project will employ the surface modified SiC as the support for dispersing bimetallic nanoparticles and investigate the LSPR effects of bimetallic nanoparticles through adjusting and controlling their composition, structure and particle size. By theoretical calculation and experimental investigation, we will analyze the interactions of bimetallic components, and the synergistic catalytic mechanism between bimetallic nanoparticles and SiC support; elucidate the dependence of the catalytic activity of different catalysts; and clarify the influences of different functional groups in furan derivatives on the hydrogenolysis performances over the bimetallic catalysts. The goal of this project is to get an efficient and stable SiC based bimetallic photocatalyst for the hydrogenolysis of furan derivatives.

呋喃及其衍生物的催化加氢开环可制备各种醇、酸和酯类物质，是生物质转化为多种化学品的关键过程之一。Pt、Pd、Ru等金属常用于呋喃化合物加氢开环，但反应多在高温高压下进行。Au纳米颗粒由于局域表面等离子体共振（LSPR）效应，其自由电子吸收可见光，成为高能热电子富集在表面，可高效活化反应物。因此，将Au掺杂到Pt、Pd、Ru等金属粒子中形成双金属纳米颗粒，可望利用可见光，在温和条件下催化呋喃化合物加氢开环。同时，n型SiC与功函数较大的金属形成肖特基接触时，其光生电子能够迅速转移到金属活性位，从而增强金属粒子的催化活性。本项目采用表面修饰的SiC负载双金属纳米颗粒，通过颗粒组分、结构和尺寸的调控研究其LSPR效应，并探讨不同组分之间以及金属与SiC之间的协同催化机理，建立不同纳米颗粒结构与其催化活性之间的关系，明晰呋喃化合物不同官能团对加氢开环性能的影响。

由于光催化能够有效利用太阳能，在温和条件下促使反应进行，并且能够定向的选择性合成目标产物，提高目标产物的产率，因此其在有机合成中的应用引起了广泛的关注。在本项目的支持下，我们发展出碳化硅表面修饰改性的控制方法，实现具有可控尺寸和结构的双金属纳米颗粒在碳化硅表面负载，同时阐明了呋喃氢解及多种有机反应在双金属纳米颗粒表面的活化机制，建立了不同纳米颗粒的尺寸、组分和结构与其局域表面等离子体共振效应和控制步骤活化能之间的匹配关系。. 本项目制备出SiC负载的非接触型Au-Ru双金属纳米颗粒，利用光照下Au/SiC间局域等离子体吸收所产生的高能电子注入和SiC/Ru间肖特基接触所引起的电子定向迁移的协同作用，在环境温度和较低压力下，催化呋喃化合物加氢开环。光照条件下，糠醇在5小时内的转化率大于99%，其中1,2-戊二醇的选择性达到61.5%。短的入射波长和高的光照强度有利于糠醇分子在Ru纳米颗粒表面斜式吸附，进而有助于提高转化率和1,2-戊二醇的选择性。. 我们也发现SiC负载的Pd-Au非接触型双金属催化剂具有优异的光催化硝基苯类化合物选择性加氢性能，在室温常压下，仅需半小时即可使转换频率（TOF）高达1715 h-1，是目前报道的最高值之一。SiC负载的Ni-Pd双金属催化剂则在溴代和氯代芳香烃化合物的Suzuki-Miyaura反应中展现出很高的光催化活性。此外，SiC负载的单金属纳米颗粒，纳米螺旋碳负载的Pd纳米颗粒，以及石墨烯负载的活泼金属纳米颗粒（如Cu、Ru），均在光催化有机合成以及光催化传统费托合成反应中展现出优异的催化活性。. 在以上研究基础上，我们在Journal of the American Chemical Society、ACS Catalysis等国际期刊上发表研究性论文12篇，申请专利3件，目前已授权1件，在国际会议中做口头报告2次，培养6名学生，其中2名硕士生已经顺利毕业，仍有4名博士生在读。目前，已顺利完成此项目所有的研究目标，执行完毕所有研究计划。