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

开发流动条件下原位 MAS NMR 确定本征动力学和阐明非均相催化氢化反应机理的方法

• 批准号: 243834932
• 负责人: Professor Dr. Michael Hunger
• 金额: --
• 依托单位: Institut für Technische Chemie (ITC)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/243834932?language=en
• 关键词: Development; methods; determining; intrinsic; kinetics

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.

将开发流动条件下的原位 MAS NMR 光谱方法，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，该实验首先包括待氢化反应物在活化和还原的固体催化剂上的吸附，随后通过以下方法研究流动氢气下的氢化动力学：原位 MAS 核磁共振波谱。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分开。通过优化实验参数和反应条件以及选择和研究合适的反应物分子，对不同金属改性沸石催化剂和新型固体催化剂（例如金属改性FSP-铝硅酸盐纳米粒子）的本征加氢活性进行了比较研究。将在介孔载体和金属有机框架上制备金属纳米粒子的微乳液中进行FSP（火焰喷雾热解）。通过这种方式，期待关于金属原子和簇的性质、组成和尺寸以及不同载体和主体材料对上述催化剂体系的固有加氢活性的影响的新发现。为了准备非均相催化氢化反应的 (ii) 机制的研究，计划进行仲氢诱导极化 (PHIP) 的实验。在仲氢分子的两个氢原子成对并入反应物的情况下，例如通过烯烃的氢化，初始自旋顺序转化为大的非平衡自旋极化（超极化）。相应的核磁共振信号的强度大大增强，具有特征性的反相形状。具有高本征加氢活性的金属改性固体催化剂将应用于不同尺寸和仲氢吸附性能的烯烃加氢，并在流动条件下通过原位MAS核磁共振波谱研究其PHIP效应。此外，计划进行侧重于氢化反应产物分子和吸附位点局部结构中从 1H 核到异核的超极化转移的实验。这些研究的重点是阐明多相催化氢化反应的机制，除其他外，应结合文献中提出的机制进行讨论。

项目成果

Relationships between the Hydrogenation and Dehydrogenation Properties of Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Studied by In Situ MAS NMR Spectroscopy and Conventional Heterogeneous Catalysis

• DOI: 10.1021/acs.jpcc.5b11367
• 发表时间: 2016-02-01
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY C
• 影响因子: 3.7
• 作者: Obenaus, Utz;Neher, Felix;Hunger, Michael
• 通讯作者: Hunger, Michael

Parahydrogen-Induced Hyperpolarization inside Meso- and Micropores of Pt-, Rh-, Ir-, and Pd-Containing Solid Catalysts

仲氢诱导的含 Pt、Rh、Ir 和 Pd 固体催化剂介孔和微孔内的超极化

• DOI: 10.1021/acs.jpcc.7b01899
• 发表时间: 2017
• 期刊: Journal of Physical Chemistry C
• 影响因子: 3.7
• 作者: U. Obenaus;S. Lang;R. Himmelmann;M. Hunger
• 通讯作者: M. Hunger

Separation of Anti-Phase Signals Due to Parahydrogen Induced Polarization via 2D Nutation NMR Spectroscopy.

通过 2D 章动 NMR 光谱分离仲氢诱导极化引起的反相​​位信号

• DOI: 10.1002/cphc.201601227
• 发表时间: 2017
• 期刊: Chemphyschem : a European journal of chemical physics and physical chemistry
• 作者: U. Obenaus;G. Althoff-Ospelt;S. Lang;R. Himmelmann;M. Hunger
• 通讯作者: M. Hunger