含-(CF2)nSO3H基团纳米超强酸的构建

Development of novel acid catalytic materials is of important theoreticalsignificance and practical value to solve the problems of environmental pollutionand energy shortage. In all kinds of acid catalysts, hybrid inorganic/organicnano-superacids have an edge. Based on our previous work with organic nanoparticlecatalysts, the present proposal designs the immobilization of typical organicBrønsted superacid groups on inorganic nanoparticles to prepare novel superacidcatalysts. The inorganic nanoparticle supports are synthesized and coated withazide and then covalently bonded with organic Brønsted superacid groups via "clickreaction", providing mutually reinforcing catalytic activity of Lewis acidic siteson the inorganic cores and Brønsted acidic sites of surface functional groups. Thevarious hybrid organic/inorganic nano-superacids are synthesized and characterizedto compare the relative catalytic activity and stability of each for seeking novelsuperacid materials with unique properties. Meanwhile, with the degradation ofchlorinated aromatic compounds as the model reaction, their superelectrophiliccatalytic activity and mechanism are investigated bounding up the hybridmicrostructure. Further, based upon all results, optimization or reconstructioneither of inorganic cores or organic superacids groups unit and their bonding modeis proposed. The proposed target materials not only maintain high catalyticactivity of organic superacids, but also have high intensity and stability ofinorganic materials and facile recovery and reuse of heterogeneous catalysts. Thisproject would promote the interdisciplinary coalescing of chemistry, materials,environment and energy.

开发新型酸催化材料对解决环境污染和能源短缺等问题具有重要的科学意义和实用价值。在各种类型的酸催化剂中，无机与有机基团共价键合的纳米超强酸具备显著的优越性。本项目设计制备无机纳米材料并进行表面叠氮化修饰，通过“点击反应”将有机Brøted超强酸功能基团密集键合在无机纳米材料上，形成无机核上的Lewis酸和有机Brøted酸相互促进的催化活性中心，合成和表征一系列结构新颖的无机/有机纳米超强酸，经过催化活性及稳定性等实验，筛选出一批具备独特性能的新型超强酸材料；并以卤代芳烃催化降解为反应模型，探索这类超强酸超亲电选择性催化机理，研究微观结构与选择性转化控制规律的关系。在此基础上进一步优化无机核和有机超强酸单元结构及其键合方式。所合成的目标材料不仅具备机超强酸的高催化活性，还具有无机材料的高强度和高稳定性，以及异相催化剂易于再生的特点。本项目是化学、材料、环境和能源等学科的交叉生长点。

按研究计划制备了11种结构新颖的固体酸接枝-(CF2)nSO3H基团纳米或介孔超强酸。通过元素掺杂强化Lewis和Brønsted酸性的手段，制备了具有Lewis-Brønsted酸协同催化效应的过硫酸化固体超强酸和离子液体超强酸，并对产物进行了较为系统的表征与性能测试，获得了一些具有理论和应用价值的结果和结论。重要的成果包括：（1）较完整地展现了设计制备的超强酸所具备的高效、绿色的催化性能。（2）由于半径相近，掺杂离子会置换固体晶格上的中性原子，形成受缚的强Lewis酸（碱）位点，从而获得了在固体界面设计、建造、调节Lewis酸（碱）强度的新方法。（3）Lewis-Brønsted酸的协同作用显著活化“惰性”反应物，使得氟苯与羧酸也能在较温和条件下完成Friedel-Crafts酰基化反应、使得某些“易重排”的碳正离子中间体不重排。