Development of methods for determining the intrinsic kinetics and for clarifying the mechanisms of heterogeneously catalyzed hydrogenation reactions by in situ MAS NMR under flow conditions

将开发流动条件下的原位MAS NMR光谱法，其可用于（i）测定金属改性固体催化剂的固有加氢活性和（ii）阐明这些反应的机理。（i）固有氢化活性的测定将通过半间歇实验进行，该半间歇实验首先包括待氢化的反应物在活化和还原的固体催化剂上的吸附，随后通过原位MAS NMR光谱法研究流动氢气下的氢化动力学。这种方法的优点是将氢化反应的时间依赖性与反应物和反应产物的传输限制以及时间依赖性催化剂失活解耦。通过对实验参数和反应条件的优化以及反应物分子的选择和考察，比较了不同金属改性沸石催化剂和新型固体催化剂（如金属改性的FSP-硅铝酸盐纳米颗粒）的本征加氢活性（FSP：火焰喷雾热解），在微乳液中在介孔载体和金属有机框架上制备金属纳米颗粒。通过这种方式，新的发现的性质，组成，和金属原子和簇的大小以及不同的载体和主体材料对上述催化剂体系的本征加氢活性的影响是预期的。准备研究的（ii）机制的非均相催化氢化反应，实验上使用仲氢诱导极化（PHIP）的计划。在将仲氢分子的两个氢原子成对并入反应物中的情况下，例如通过烯烃的氢化，初始自旋序被转化为大的非平衡自旋极化（超极化）。相应的NMR信号，这是强烈增强的强度，具有特征的反相形状。具有高本征加氢活性的金属改性固体催化剂将用于加氢不同尺寸和吸附性能的烯烃与仲氢，其PHIP效应将通过流动条件下的原位MAS NMR光谱来研究。此外，实验的重点是转移超极化从1H核的异构核的氢化反应的产物分子和吸附位点的局部结构的计划。这些调查的重点是阐明非均相催化氢化反应，这应该，除其他外，在文献中提出的机制进行了讨论的机制。

Methods of in situ MAS NMR spectroscopy under flow conditions will be developed, which can be utilized for the (i) determination of the intrinsic hydrogenation activity of metal-modified solid catalysts and for (ii) elucidating the mechanisms of these reactions. The (i) determination of the intrinsic hydrogenation activity will be performed via semibatch experiments consisting at first in the adsorption of the reactants to be hydrogenated on the activated and reduced solid catalyst and, subsequently, in the study of the hydrogenation kinetics under flowing hydrogen by in situ MAS NMR spectroscopy. The advantage of this approach is the decoupling of the time-dependence of the hydrogenation reaction from transport limitations of the reactants and reaction products as well as the time-dependent catalyst deactivation. After optimizing the experimental parameters and the reaction conditions as well as the selection and investigation of suitable reactant molecules, comparative studies of the intrinsic hydrogenation activity of different metal-modified zeolite catalysts and novel solid catalysts, such as metal-modified FSP-aluminosilicate nanoparticles (FSP: flame spray pyrolysis), in microemulsions prepared metal-nanoparticles on mesoporous supports, and metal-organic frameworks, will be performed. By this way, new findings on the effects of the nature, composition, and size of metal atoms and clusters as well as different support and host materials on the intrinsic hydrogenation activities of the above-mentioned catalyst systems are expected. Preparing the studies of the (ii) mechanisms of heterogeneously catalyzed hydrogenation reactions, experiments on the use of parahydrogen-induced polarization (PHIP) are planned. In the case of a pairwise incorporation of the two hydrogen atoms of a parahydrogen molecule into a reactant, such as by hydrogenation of olefins, the initial spin order is converted into a large nonequilibrium spin polarization (hyperpolarization). The corresponding NMR signals, which are strongly enhanced in their intensities, have characteristic antiphase shapes. Metal-modified solid catalysts with high intrinsic hydrogenation activities will be applied for hydrogenating olefins of different sizes and adsorption properties with parahydrogen, and their PHIP effect will be studied by in situ MAS NMR spectroscopy under flow conditions. Furthermore, experiments focusing on the transfer of hyperpolarization from 1H nuclei to hetero-nuclei in product molecules of hydrogenation reactions and in the local structure of adsorption sites are planned. These investigations focus on elucidating the mechanisms of heterogeneously catalyzed hydrogenation reactions, which should be, inter alia, discussed in relation to mechanisms suggested in literature.