非活泼芳烃氧化偶联反应金纳米簇催化剂的构建及催化机制研究

Synthesis of biaryls via traditional couplings such as Suzuki coupling bears multiple reaction steps, high energy consumption, heavy pollution and other environmental issues. Direct oxidative coupling of nonactivated arenes to biaryls is a much desirable green process, but it has not been brought into practical utilization up to date. In this context, molecular oxygen O2 is a cheap oxidant with the highest atomic economy. However, the heterogeneous catalytic system of oxidative coupling of nonactivated arenes with O2 in the absence of an additive remains a highly challenging issue. This project designs and prepares gold nanoclusters catalysts anchored on the porous hypercrosslinked ionic polymers (HIPs) with large surface area and high ionic site densities, aiming to highly efficiently catalyze the oxidative coupling of nonactivated arenes in the absence of an additive with convenient catalyst recovery and reuse. Catalyst design and preparation, composition and structure, physical and chemical properties, and catalytic activities and stability, will be studied. Together with catalyst characterizations, influences of ionic site densities, functional groups and porous structure of the HIPs on the particle size distribution and electronic properties of gold nanoclusters will be investigated and recognized. Further, influences of catalytic performances by key parameters will be elucidated, such as particle size distribution, electronic properties and pore structure, based on which the reaction mechanism is discussed. This study will provide a new route and scientific foundation for establishing green heterogeneous catalytic process of highly effective oxidative coupling of nonactivated arenes with O2 in the absence of an additive to biaryls.

工业上主要采用Suzuki等传统偶联方法制备联芳烃，具有反应步骤多、能耗高、污染重等问题。非活泼芳烃直接氧化偶联制联芳烃是至今未得到实际应用的绿色催化工艺，固体催化剂催化的无助剂非活泼芳烃-O2氧化偶联制联芳烃更具有原子经济性，也更是极具挑战性的难题。本项目为实现无助剂非活泼芳烃-O2氧化偶联制联芳烃的高效多相催化工艺，设计和制备高比表面积-丰富离子位的超交联多孔离子聚合物负载Au纳米簇催化剂。重点研究Au纳米簇催化剂的设计和制备、组成结构和物化性质、以及催化活性和稳定性；结合表征深入分析认识超交联多孔离子聚合物的离子位密度、功能基团、孔结构、纳米限域效应等对Au纳米簇的物化性质的影响，研究Au纳米簇催化剂的粒径分布、电子性质和孔结构对催化性能的影响，揭示纳米Au催化非活泼芳烃-O2氧化偶联制联芳烃的作用机制，为构建无助剂非活泼芳烃-O2氧化偶联的绿色高效多相催化工艺提供新途径和科学依据。

本项目面向偶联反应绿色催化工艺，致力于设计构建高活性贵金属纳米簇多相催化剂。在该项目的具体实施过程中，制备了多类别的中性/离子型多孔有机聚合物材料，这些材料具有较高的比表面积、丰富的功能基团和高密度的离子位，以这些材料作为载体制得了负载贵金属纳米簇的催化剂材料，实现了温和条件下偶联反应的高效转化。本项目主要取得了以下进展：（1）构建了超交联多孔离子聚合物材料，该材料具有高比表面积和高密度离子位，作为载体实现了Au0纳米簇催化剂的制备。该催化剂实现了无助剂条件下非活泼芳烃-O2氧化偶联的高效转化，并且催化剂可以多次循环回收复用。（2）无金属参与下成功构建了羧酸功能化超交联有机聚合物，该材料具有高比表面积和丰富的羧酸基团，作为载体实现了Pd0纳米簇催化剂的制备。该催化剂在无助剂非活泼芳烃-O2氧化偶联反应中表现出高催化性能，联芳烃产物收率高达18.0%。选择性高达98.6%，TON高达300，TOF高达150 h-1，并且催化剂可以多次循环回收复用。（3）采用后修饰法设计制备出了新型席夫碱-咪唑功能化的MOFs材料，该材料具有高比表面积和丰富的功能基团，作为载体实现了Pd0纳米簇催化剂的制备。该催化剂实现了温和条件下Suzuki偶联反应的高效转化，联芳烃产物收率>99%，并且催化剂可以多次稳定回收复用。面向绿色催化应用领域，本项目为设计应用导向的绿色高效多相催化工艺提供新的思路和研究基础。受本项目资助，总共发表论文6篇，申请专利5项，其中授权专利4项。