核苷酸的界面组装与原位还原协同调控金属催化肉桂醛选择性加氢研究

In the catalytic hydrogenation of α,β-unsaturated aldehydes, it is difficult to achieve both high catalytic activity and high chemoselectivity toward carbonyl groups. To solve this problem, the regulation of metal dispersion and electronic property as well as and the rational construction of steric hindrance will be simultaneously achieved based on the interfacial assembly and the in-situ reduction properties of nucleotide derivatives. First, the mechanisms on the interaction modes between metal precursors and nucleotide derivatives will be investigated on the surface of magnetic nanoparticles. Then the effects of functional groups and molecular assembly modes on the size, valence distribution and coordination environment of metal species will be disclosed. Next, the influence of metal loading and dispersion, electronic property as well as steric hindrance, on the conversion, chemoselectivity and turnover frequency will be studied for the selective hydrogenation of cinnamaldehyde. Finally, the influence of coupling between slurry reactors and magnetic separation on the reaction processes will be investigated, to achieve the intensification techniques for the selective hydrogenation of cinnamaldehyde. The achievements of this proposal will provide scientific guidance on the eco-friendly and efficient industrial production of α,β-unsaturated alcohols.

本申请针对当前α,β-不饱和醛加氢研究中普遍存在的高催化活性与高C=O选择性不易同时达到的问题，利用核苷酸的界面超分子组装与原位还原机制，同时实现金属分散度的控制、电子性质的调控以及空间位阻的合理构筑。揭示金属前驱体与核苷酸衍生物在磁性颗粒表面的相互作用模式，获得金属组分的尺寸、价态分布、配位环境随核苷酸的官能团、组装模式的变化规律；揭示催化剂的金属负载量与分散度、电子性质、空间位阻对肉桂醛加氢反应的转化率、选择性、转换频率的影响规律；进而，研究浆态床反应器和磁分离耦合结构对反应过程的影响规律，形成肉桂醛选择性加氢的过程强化技术。本申请的研究成果将为α,β-不饱和醇的绿色、高效工业生产提供科学基础。

针对肉桂醛选择性加氢，在鸟苷-5'-单磷酸（GMP）的调控下，采用低温水热法合成了一系列3D Pd催化电极，GMP-Pd/NF具有良好的导电性和浸润性，有利于活性氢在电极表面上的吸附和解吸，具有较高的电化学活性面积、优异的电荷转移能力。通过优化电解质组成、电流密度、反应时间以及反应物浓度，发现阴极为中性电解质时，在20 ℃、电流密度为10 mA/cm2下反应6 h，CAL的转化率为71.1%，COL的选择性可达90.1%，法拉第效率达到68.2%。机理研究表明，阴极电解液中的碱金属阳离子与pH值对COL的选择性起到至关重要的作用，α, β-不饱和醛末端的大π键共轭体系有利于C=O键的选择性加氢。以氧化锡为载体，通过吸附-还原法制备了不同Pd负载量的Pd/SnO2催化剂。当电流密度为3.33 mA·cm-2时，在15℃下恒流电解8 h，CAL转化率为84.88%，法拉第效率达到65.25%，COL选择性达到78.85%。以浆态电化学反应器对CAL进行电加氢反应，Pd/SnO2的催化性能优于商用Pd/C，在CAL转化率为98.22%时，FE为46.75%，COL选择性达到73.76%。该项目的研究成果为肉桂醇的高效、绿色合成提供了新途径。