钛氧纳米管上催化功能烯定向氢甲酰化活性中心的设计与构筑

Hydroformylation (the "oxo reaction") is one of the most important catalytic processes to produce aldehydes and alcohols, which are versatile intermediates and building blocks for pharmaceuticals, commodity and fine chemicals. In consequent, over past decades, a great deal of efforts has been put to increase the regioselectivity as well as reaction rate; and to decrease the undesired side products of reaction. However, the hydroformylations of functionalized olefins,e.g. vinyl acetate (I) and 1,3-butadiene (II), and so on, are still uncontrollable regioselectively. Arguably, the reason comes from the lack of regioselectivity in these reactions. For example, the dihydroformylation of 1,3-butadiene can form up to 14 different aldehyde products and the hydroformylation of vinyl acetate gives maily branched aldehyde. So, the controlling regioselectively hydroformylations of (I) and (II) as well as enhancing the regioselectivity in these reactions are important academic problems in organic catalysis. It is well known that complexes containing Rh, Co and Ir elements can act as catalytic active sites for hydroformylation of olefins, and it has also been reported that the Rh/ligand (L-L) complexes might be good regioselective catalyst species. Based on the one-dimensional channels and surface structures of TiO2 nanotubes (TNTs), we intend, in this proposal, to design strategically and construct catalytic active sites that are Rh,Co,Ir/ligands (P-nanotube-P) complexs on the inner and outer surfaces of TNTs through chemical bonds for regioselective hydroformylations of (I) and (II); utilize synergistic effects caused by both of TNTs' confinement effect and the catalytic active sites to control regioselectively hydroformylations of functionalized olefine represented by the vinyl acetate and 1,3-butadiene. We are going to construct catalytic active sites via three procedures. 1) We anchor ligands containing P donors to TNTs by chemical bonds firstly, then synthesize complexes with Rh, Co or Ir elements on the modified TNTs. 2) We synthesize complexes with target structures firstly, and then attach these complexes to TNTs through chemical reactions. 3) We deposit nano metal clusters on TNTs via incipient wetness impregnation-chemical reduction procedure firstly,and then let them react with ligands. We are going to characterize the samples obtained via three processes with ICP, AAS, XRD, 31PNMR, HNMR, MS, ESR, PL, CV, UV-vis, FTIR，EXAFS, Raman spectroscopy, DRUVS, IRDRSA, XPS, EDX, LEED, AES, BET, SAED, TG-DTA, TEM, SEM, AFM, SFG,and so on; evaluate their catalytic performances for hydroformylation of (I) and (II); reveal the synergistic effects caused by both of TiO2-NTs' confinement effect and the catalytic active sites on the catalytic performances of the samples obtained; explore the essence and basic law of functionalied TiO2-NTs catalysts for regioselective hydroformylation of (I) and (II).

功能化烯（FO，Functionalized Olefins）氢甲酰化的定向控制是有机催化中尚未解决的科学问题之一。项目利用钛氧纳米管的一维圆柱介孔和表面结构，设计通过化学键，在钛氧纳米管的内、外表面上构筑FO定向氢甲酰化催化活性中心；探索纳米管限域作用和活性中心两者结合的协同效应，实现FO氢甲酰化反应的定向调控，探针反应以醋酸乙烯和1,3-丁二烯为原料。通过三个途径构筑活性中心:1）在纳米管上锚定设计的含P等配体后，再和含Rh、Co、Ir化合物反应；2）将合成的目标结构配合物锚接到纳米管上；3）在纳米管上先铆钉纳米金属簇，再将其和配体反应。以对比方式研究催化活性中心的结构,测试、评价其稳定性和催化性能；揭示结构和协同效应对活性中心性能等的影响；从实验和理论两个层面认识功能纳米管负载催化剂催化FO定向氢甲酰化的本质和规律。项目将在纳米管功能化、协同效应和FO定向氢甲酰化研究领域取得新成果。

项目在一维钛氧纳米管等载体上构筑设计的催化活性中心，研究合成了一批具有单、双催化活性中心的催化剂；系统地表征了它们的结构；评价了它们在不同反应条件下对醋酸乙烯酯、苯乙烯和丙烯酰胺等底物的氢甲酰化反应的催化性能，分析归纳了活性中心的结构对催化反应区域选择性的影响。项目也对氢甲酰化反应导致的有关问题，如重金属、CO和有机物污染问题，进行了研究。项目完成的主要工作：1）为了在钛氧纳米管等载体上构筑目标催化性能的活性中心，项目合成了不同组成、形貌和表面酸性的载体。合成的载体有钛氧纳米管、硼和锆修饰的钛氧纳米管、硅酸镁纳米管、层状氧化锆和片状g-C3N4等。2）项目研究在这些载体上构筑了单、双催化活性中心。使用的方法包括：溶胶浸渍-光或化学还原法、分步浸渍-光或化学还原法以及浸渍惰气氛中控温焙烧法等。3）项目表征和揭示了所构筑催化剂的结构、活性中心的化学状态及其与载体的相互作用。4）项目评价所合成催化剂对醋酸乙烯酯等的氢甲酰化反应的催化性能。5）项目比较研究了单、双催化活性中心及催化剂表面酸碱性等对氢甲酰化反应区域选择性的调控作用。项目获得的重要结果和科学意义主要表现在：1）钛氧纳米管等载体上构筑的含Rh等金属催化活性中心能在较温和的条件下催化烯烃氢甲酰化，且活性中心有好的稳定性；2）含Rh的双催化活性中心的协同效应可提高催化剂对醋酸乙烯酯氢甲酰化的催化活性；3）催化剂的表面酸碱性对含碱性官能团烯烃的氢甲酰化反应的区域选择性有很大的影响，这是均相催化剂所不具备的；4）通过浸渍-控温焙烧法制备的Rh基催化剂具有良好的催化性能。该方法简单，可增强活性中心和载体的相互作用，提高催化剂的催化性能。项目完成的任务：已发表标注国家自科基金资助的学术论文和会议论文24篇，申请发明专利一项。通过项目的支持，已有4位博士生，3位硕士生获得他们的学位。项目选派一博士后、两博士生分别到澳大利亚、加拿大和法国大学进行交流培养。