Guest/Host Interactions in High-Silica Zeolites

Raul F. Lobo教授将研究有机结构导向剂在合成的高硅沸石中的主客体相互作用，以获得有机结构与孔隙结构之间的相关性。利用各种衍生化烷基铵盐模板，从纯硅分子筛到高硅硅铝分子筛的合成将系统地发展，并将影响笼和孔结构。此外，Lobo教授将研究如何在合成过程中控制缺陷和Al3+位点的密度和位置。热重法将用于测量内部体积。多核固体核磁共振实验将用于表征相互作用，氘核磁共振将研究有机分子的动态状态作为温度和分子大小的函数，以及其他选定标签的有机分子的核磁共振来描述几种沸石结构中的分子运动。29Si和1H的异核化学位移相关将用于获得关于四面体Al3+阳离子和沸石框架缺陷位置的分子排列信息。为了表征缺陷，还将进行x射线衍射实验，其中25 ？将合成纯ZSM-11的单晶。通过核磁共振实验，特别是自旋回波双共振（SEDOR, 23Na{1H}）和旋转回波双共振（REDOR, 29Si{23Na}）来确定合成沸石的有机和无机组分的空间接近性。本研究将有助于改进沸石材料的设计和合成。这些信息也将反映在用于模板选择和沸石合成的更精确的分子力学和量子力学模型中，并将改进沸石中输运和扩散的分子模拟模型。从外部来看，这将为设计具有定制孔结构和活性位点分布的催化剂和分子筛分离材料提供更强的基础依据。这些化学活性物质支持了化学工业的主要部分，包括石化、燃料、精细化工、农用化工等。

Prof. Raul F. Lobo will study the host-guest interactions of organic structure-directing agents in as-synthesized high-silica zeolites, in order to obtain correlations between organic structure and pore structure. The synthesis will evolve systematically from pure silica cathrasils to high-silica silica-alumina zeolites, utilizing various derivatized alkylammonium salt templates, and will affect cage and pore structures. Additionally, Prof. Lobo will investigate how to control the density and location of defect and Al3+ sites during the synthesis. Thermogravimetry will be used to measure internal volume. Multinuclear solid-state NMR experiments will be used to characterize the interaction, deuterium NMR to investigate the dynamic state of organic molecules as a function of temperature and molecule size, and NMR of other selected labels of the organic molecule to describe the molecule motion in several zeolite structures. Heteronuclear chemical shift correlation of 29Si and 1H will be used to obtain information on the molecular arrangement with respect to the location of tetrahedral Al3+ cations and zeolitic framework defects. To characterize the defects, also X-ray diffraction experiments will be done, for which 25 ? single crystals of pure ZSM-11 will be synthesized. The NMR experiments and in particular the spin-echo double resonance (SEDOR, 23Na{1H}) and rotational echo double resonance (REDOR, 29Si{23Na}) will be done to determine the spatial proximity of organic and inorganic components of the as-synthesized zeolite. The proposed research will help to improve the design and synthesis of zeolitic materials. This information will also be reflected in more accurate molecular mechanics and quantum mechanical models used for template selection and zeolite synthesis, and will improve the molecular simulation models of transport and diffusion in zeolites. Extrinsically, it will provide a stronger fundamental basis for the design of catalysts and molecular sieve separation materials with tailor ed pore structure and active site distribution. These chemically active materials support a major fraction of the chemical industry, including petrochemical, fuels, fine chemical, agrochemical, and others.