Towards High Selectivity MFI Molecular Sieve Membranes through Microstructural Optimization

建议没有。项目编号：cts -0091406项目类型：发起人：首席研究员：Michael Tsapatsis机构：马萨诸塞大学阿默斯特分校通过微结构优化实现高选择性分子筛膜本项目的目标是将多晶沸石膜的微结构与膜分离性能联系起来。本项目研究了同一种沸石（高硅MFI）的两类膜，它们的微观结构、稳定性和分离性能都有明显的不同。这些薄膜是用二次生长技术制备的。光学和电子显微镜结合x射线衍射在纳米水平上揭示了这些薄膜的微观结构差异。结构信息用于将这些差异与膜的特性联系起来，如选择性和对膜开裂的敏感性。研究了避免裂缝形成的途径和选择性密封裂缝的方法。沸石和相关的分子筛是具有微孔框架的晶体材料，能够在亚纳米水平上过滤分子。结晶分子筛膜的形成使具有相似物理化学性质的分子得以分离，而这些分子是其他方法难以分离的。因此，沸石膜的制备越来越受到世界各国的重视。最近的进展已经带来了商业化的努力，并为气体、液体和蒸汽分离的应用提供了新的机会。潜在的应用包括通过渗透蒸发分离特殊化学品、碳氢化合物异构体、永久性气体以及水/酒精溶液。为了维持第一代沸石膜的初步成功，并找到当前膜技术无法实现的新处理策略的应用（例如，异构化膜反应器，手性分离等），需要将合成创新与对合成-微结构-性能相互关系的基本理解相结合的研究工作。这项工作强调微观结构-性能问题。其结果将有助于合理的发展，而不是试错策略，形成高性能分子筛膜量身定制的特定分离应用。

Proposal No.: CTS-0091406Proposal Type: Investigator InitiatedPrincipal Investigators: Michael Tsapatsis Institution: University of Massachusetts Amherst Towards High Selectivity Molecular Sieve Membranes through MicrostructuralOptimizationThe objective of this project is to relate the microstructure of polycrystalline zeolite films to membrane separation performance. The project involves the study of two classes of films of the same zeolite (high-silica MFI) with distinctly different microstructure, stability and separation performance. These films are prepared by the secondary growth technique. Optical and electron microscopy are combined with X-ray diffraction to unravel the microstructural differences of these films at the nanometer level. The structural information is used to relate these differences to membrane properties likeselectivity and susceptibility to membrane cracking. Approaches for avoiding crackformation and methods for selective crack sealing are being investigated.Zeolites and related molecular sieves are crystalline materials with microporous frameworks capable of filtering molecules at the subnanometer level. The formation of crystalline molecular sieve membranes enables separations of molecules with similar physicochemical properties that are difficult to separate by other methods. As a result,efforts towards zeolite membrane preparation are receiving increasing attention worldwide. Recent advances have resulted in commercialization efforts and suggest new opportunities for applications in gas, liquid and vapor separations. Potential applications include separations of specialty chemicals, hydrocarbon isomers, and permanent gases as well as water/alcohol solutions by pervaporation. In order to sustain the initial success of first-generation zeolite membranes, and to find uses in new processing strategies unattainable with the current membrane technology (e.g., isomerization membrane reactors, chiral separations, etc.), research efforts are required that will combine synthetic innovation with fundamental understanding of the synthesis-microstructure-performanceinterrelationships. This work emphasizes the microstructure-performance issues. Its outcome will contribute to the development of rational rather than trial-and-error strategies for the formation of high performance molecular-sieve membranes tailored to specific separation applications.