杂多酸盐/有机配合物杂化材料协同效应及催化纤维素绿色选择氧化

Hybrids of polyoxometalate/organic complex are an unique composite materials combining rigidness, size stability of inorganic components and flexility, modifiability of organic ones, which can be endowed with higher added values than each of the components. However, only few efforts have been paid on investigaton of relationships between the structures and performances of the hybrids. In this project, selective oxidation of primary hydroxy in cellulose is selected as probe, and following studies will be carried out. (1) A series of the hybrids will be designed and prepared. Their catalytic performances of selective oxidation of cellulose will be investigated carefully using molecular oxygen as oxidant.(2) The properties and catalytic performances of the hybrids will be tuned by modifying polyoxometalates and organic moleculars. The methods and conditions for preparation of the hybrids will be also optimized.The hybrid catalysts with higher added values will be obtained consequently,and the reaction conditions for oxidation of cellulose will be optimized.(3)The tunable preparation methods and relationships between the structures and performances of the hybrids will be studied mainly combining kinetics and quantum calculation. Based on the above studies, the potential capacities and advantages of the hybrids as catalysts for selective oxidation will be disclosed, the theoretical and experimental supporting will be provided for design, preparation and optimizing of the hybrids.So the project is of significant importance in both fundamental and applied aspects.

杂多酸盐/有机配合物是一类集杂多酸的刚性、尺寸稳定性和有机配合物的韧性、可修饰性于一体的性能优化互补的杂化材料。但对其构效关系的研究仍然非常欠缺。本项目以纤维素伯羟基的选择性氧化为探针反应，将设计制备系列杂多酸盐/有机配合物杂化材料，以分子氧为清洁氧源，考察其催化活性。通过对杂多酸和有机配合物组成、结构的调变和修饰，来调控杂化材料的物理化学性质及催化性能，优化制备方法和条件，从而得到性能优于单一组分的催化剂，并对催化反应条件进行优化。同时，结合反应动力学研究和理论计算重点研究杂化材料的构效关系和可控制备，揭示此类杂化材料提高催化活性的优势和潜力，为功能化杂多酸盐/有机配合物杂化材料的设计合成和性能优化提供一定的理论依据和实验技术。

本项目以纤维素伯羟基的选择性氧化为探针反应，设计制备了系列杂多酸盐/有机配合物杂化材料，以分子氧为清洁氧源，考察了其催化活性。本项目构建了以下杂多酸/有机配合物杂化材料：.（1）通过共价键结合的方法，将系列席夫碱Pd（II）配合物与Keggin型缺位硅钨酸K8[SiW11O39] (POM)结合，制备了系列杂化材料Pd(salen)-POM；（2）将氮杂卡宾配合物的盐酸盐 (iPr•HCl) 分别以离子交换和共价接枝的方法与Keggin型缺位硅钨酸K8[SiW11O39]及Pd取代的硅钨酸K6[SiW11PdO39]和钼酸盐KPd Mo6O19杂化，制得杂化材料(iPr•HCl)6SiW11PdO39，(iPr.HCl)Pd Mo6O19及(iPr•HCl)Pd NH2(CH2)3SiW11O39；（3）将分子筛SBA-15用离子液体修饰后，用来负载系列Keggin型杂多酸盐KnXW11PdO40•12H2O (X=Si, n=6; X=B, n=7; X=P, n=5)，制得系列负载型杂化材料；（4）通过离子交换法将离子液体[C4mim]Br与Keggin型杂多酸H3-xPMo12-xVx040 (x=0, 1, 2)杂化，制得[C4mim]3+xPMo12-xVxO40 (x=0, 1, 2)杂化材料；（5）用一步水热法直接将Keggin型杂多酸负载到H3+xPMo12-xVxO40 (x=0, 1, 2) 负载到金属有机框架化合物MIL-100(Fe)中，形成H3+xPMo12-xVxO40/MIL-100(Fe) (x=0, 1, 2)杂化材料。.以NHPI为催化剂，上述所得杂化材料为共催化剂，分子氧为氧化剂，建立了杂多酸盐/有机配合物杂化材料—NHPI—O2共催化体系，考察了其催化微晶纤维素氧化的性能。结果表明，和单一组分相比，杂化材料各组分间能够表现出明显的协同效应。所得催化体系对纤维素伯羟基的氧化表现出了高活性和高选择性，产物中羧基的含量最高可达到97.6 mmol/kg，且纤维素的降解得到了很好的控制，其粘均聚合度的降低值在100以内。.以上成果的取得，不仅创建了新的具有非常广阔应用前景的绿色催化体系，同时为调变杂多酸盐/有机配合物杂化催化剂的组成和结构，进而调控其催化性能，实现催化剂的可控制备积累了经验。