基于含氟载体外围活化策略的金属酰基中间体高效构建与转化

Carbonylations of alkenes or alkynes with CO have 100% atomic efficiency, and are used to produce aldehydes, ketones, carboxylic acids and derivatives. However, the catalysts used in there reactions often suffer from several fundamental problems such as catalyst poisoning, activation with acids and limited selectivities etc. One key reason is related with complicated reaction pathways and the lack of understanding of important reaction intermediates, such as metal acyls. This application focuses on the influence of functional sites adjacent by space to the metal acyl intermediates. As observed in our initial study, pyridine group in the ligand and the addition of metal fluorides in CO hydrogenation are helpful for the reactivity and/or selectivity. Based on the idea of combination of homo- and heterogeneous catalysis, we will develop a series of F-contained support-metal (oxide) materials, with the "each site performs its own functions" surface based on "outer-sphere activation" strategy, to realize high efficiency, high selectivity for the carbonylation of alkynes and preparation of C2 oxygen-containing chemicals from syngas. Through systematic study of the mechanism, the relationship between catalytic performance and parameters such as surface status, crystal size, electronic state and stability etc will be clarified.

以CO作为原料的烯烃、炔烃羰化反应具有100%的原子经济性，反应产物随亲核试剂不同可以是醛、酮、（不饱和）酸及其衍生物类重要化学品。但催化剂往往存在需要酸性助剂活化、易失活、区域选择性控制能力有限等问题。一个重要原因是羰化反应本身有多条反应途径，对反应的中间体尤其是金属酰基类中间体生成和转化缺乏系统性地认识。本项目关注空间邻近的功能位点对羰化反应中酰基活性位的构建与转化的影响，基于均多相融合的思路和本项目前期工作取得的正向结果，拟开发一系列含氟载体-金属（氧化物）复合材料，构建“各司其职”的表面功能位点结构，达到表面金属酰基选择性生成和快速转化，从而实现高效、高选择性的烯烃、炔烃羰化制备酯、酰胺、醛等化学品。通过系统研究机理，获得活性位的暴露晶面、电子状态以及稳定性调控等方面的规律认识，并为非贵金属催化和以CO2为羰源的羰化新体系的建立贡献力量。

氟作为已知元素中非金属性最强的元素，能够和金属或非金属形成强配位键。本项目拟研究氟盐在碳一分子催化转化中的作用，并通过对双组分金属进行氟化，制备得到了双金属含氟材料。与常用载体(如Al2O3、SiO2等)相比，双金属含氟材料表面同时具有多金属和氧、多金属和氟的成键和空穴，这使双金属含氟材料能表现出更加丰富的表面性质。本项目围绕CO2的新型转化、炔烃羰基化等反应，开展了氟盐促进效应研究。研究发现，氟盐的添加对于反应的效率和选择性均有较大影响。在首创的CO2为碳源的催化氰基化反应中，KF的添加可以大幅提升目标反应的产率，推测氟离子对于稳定关键的Ni(I)物种有重要作用。通过使用四氟化锆为助催化剂，实现了目前已知报道的最高效率的羰基铁催化的炔烃的羰化酰胺化反应，推测四氟化锆的作用是活化十二羰基三铁更高效地解离为活性的单核羰基铁物种。同时，发现双金属含氟材料可以作为多相催化剂活化硅氢键，用于实现CO2的还原官能团化。