微（纳）级介孔羟基磷酸铁负载金催化剂的制备及其催化性能研究

Epoxides and sulfoxides are very useful and versatile intermediates for the synthesis of many commodity and fine chemicals,olefin epoxidation and selective oxidation of sulfides to sulfoxides with high selectivity are subjects of great interest from both academic and industrial points of view.This project is intended to synthesize new types of micro (nano) sized mesoporous reducible iron hydroxyphosphates using inverse microemulsion and solvothermal synthesis technology, then the nano-gold catalysts will be prepared using these materials as supports to achieve environmentally friendly catalytic synthesis for epoxides. The sufficient surface basic hydroxyls are conducive to good dispersion of gold nanoparticles,together with reducible iron components (perhaps yielding large number of oxygen vacancies, so support-gold interactions are strengthened),they will provide higher catalytic performances,then the structure- activity relationships may be established between the basic hydroxyls, oxygen vacancies and the catalytic performance, respectively. While the formation of mesoporous micro (nano) sized structure can solve some disadvantages of the iron hydroxyphosphates, such as the low surface area and the poor mass transfer performance, so the high substrate conversions and desired product selectivities will be obtained. This project will use environmentally friendly reaction system to synthesize the epoxides and sulfoxides (low-temperature liquid-phase reactions, environmentally friendly oxidants such as hydrogen peroxide, oxygen), selective oxidations of olefins and sulfides over series of nano-gold catalysts will be examined, the effects of support-gold interaction and particle size of nano-gold on the mechanisms of these reaction will be discussed, respectively. So this project will widen the research area of iron hydroxyphosphates as catalyst supports, and is very important to the development of nano-gold catalysis.

烯烃环氧化物及亚砜类化合物具有重要的经济价值，以较高产率实现烯烃环氧化及硫醚氧化到亚砜反应具有重要学术意义。本项目拟采用反相微乳液-溶剂热合成方法合成新型微（纳）级介孔羟基磷酸铁，以其为载体制备纳米金催化剂，实现环氧化烯烃及亚砜类产物环境友好的高效催化合成。载体丰富的表面碱性羟基利于纳米金的良好分散，与铁组分的可还原性（或可产生大量氧空位，从而增强载体-金协同作用）共同为纳米金催化性能的提高提供了可能，分别建立表面碱性羟基、氧空位与催化性能的构效关系；而介孔微（纳）结构的塑造可以弥补羟基磷酸盐比表面积小、质量传递差的劣势。采用环境友好的反应体系（低温液相反应，环境友好的氧化剂），考察系列纳米金催化剂对于烯烃及硫醚氧化反应的催化性能，探讨载体-金相互作用及纳米金粒径对这些反应的作用机理。本项目将促进羟基磷酸铁的合成及其作为催化载体的应用，对纳米金催化这一重要领域的发展具有一定的意义。

通过本项目实施，以反相微乳液-溶剂热合成方法合成了四种微（纳）级介孔羟基磷酸铁，分别为羟基磷酸铁（a）(Na4.55Fe(PO4)2H0.45O)、羟基磷酸铁（b）（Fe5(PO4)4(OH)3·2H2O）、羟基磷酸铁（c）(Fe3(PO4)2(OH)2)、羟基磷酸铁（d）（Fe4(PO4)3(OH)3），该方法能够有效调控羟基磷酸铁的微观形貌及介孔孔径，并对四种羟基磷酸铁进行了结构及微观形貌的表征。采用合成的四种羟基磷酸铁为催化载体，以沉积-沉淀法制备得到系列负载金催化剂，对苯乙烯环氧化、硫醚氧化到亚砜反应进行了测试，实现了预期催化性能。结合催化表征及实验数据分析，研究了载体-金相互作用等机理方面对烯烃及硫醚氧化反应的性能影响，羟基磷酸铁丰富的表面碱性羟基及微（纳）级介孔结构是取得良好催化性能重要原因。在延伸研究中，羟基磷酸铁负载铂催化剂在α，β-不饱和醛（酮）选择加氢到不饱和醇的反应中表现出较好的催化效果，催化性能主要归因于羟基磷酸铁自身路易斯强酸的存在。