Towards High Selectivity MFI Molecular Sieve Membranes through Microstructural Optimization

提案编号：CTS-0091406提案类型：研究人员发起主要研究人员：迈克尔·萨帕特研究所：马萨诸塞大学阿默斯特大学通过微结构优化获得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。该项目涉及同一沸石(高硅MFI)的两类膜的研究，这些膜具有明显不同的微观结构、稳定性和分离性能。这些薄膜是用二次生长技术制备的。光学显微镜和电子显微镜与X射线衍射相结合，在纳米水平上揭示了这些薄膜的微结构差异。结构信息被用来将这些差异与膜特性联系起来，如选择性和对膜破裂的敏感性。人们正在研究避免裂缝形成的途径和选择性裂缝封闭的方法。沸石及其相关分子筛是具有微孔骨架的结晶材料，能够在亚纳米级过滤分子。晶态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，而这些分子很难用其他方法分离。因此，沸石膜的制备越来越受到世界各国的重视。最近的进展导致了商业化努力，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汽化分离特种化学品、碳氢化合物异构体、永久气体以及水/酒精溶液。为了保持第一代沸石膜的初步成功，并在当前膜技术无法实现的新的处理策略中找到用途(例如，异构化膜反应器、手性分离等)，需要将合成创新与对synthesis-microstructure-performanceinterrelationships.的基本理解相结合的研究努力这项工作强调了微观结构-性能问题。它的成果将有助于开发合理的、而不是反复试验的策略，以形成专为特定分离应用而定制的高性能分子筛膜。

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.