Thin Metal-Organic-Framework Membranes for High Pressure Carbon Dioxide Separation

金属-有机-骨架（MOF）代表了一组新的微孔材料，作为用于气体和液体分离应用的膜。然而，还没有研究MOF膜所特有的几个基本问题，例如薄MOF膜的合成以及吸附引起的结构变化和热梯度对膜分离性能的影响，并且还没有探索传统微孔无机膜所不能达到的MOF膜的独特分离性能以用于实际应用。该项目旨在合成和表征薄的高通量微孔IRMOF-1和ZIF-69膜，并研究这些MOF膜的渗透和分离，重点是了解吸附引起的结构变化和热梯度对膜传输性能的影响。该研究将探索大孔MOF膜的独特性质，即，二氧化碳的选择渗透性随着从天然气中高压分离二氧化碳的压力而增加。所有现有的膜都表现出随着压力增加而降低的选择渗透性。工作包括开发用于制备薄（小于5 μ m）大孔MOF膜的合成方法，确定表征MOF膜质量的适当方法，研究MOF膜在高压下的渗透和分离性能，并调查吸附引起的结构变化和热梯度对膜特性的影响。膜将通过二次生长方法与纳米尺寸的MOF晶种制备。将开发分子探测方法来检查MOF膜的质量。将在大的压力范围（1-70 atm）内研究IRMOF-1和ZIF-69膜的二氧化碳、甲烷、氮气和氢气的气体渗透以及这些气体的二元混合物，特别是二氧化碳/甲烷的分离性能。在25- 150 ℃温度下进行，并与模型和分子模拟的结果进行比较。研究了气体渗透过程中膜的结构变化和热梯度，并将其与膜的气体渗透和分离性能相关联。在这个项目中进行的研究将是变革性的，因为它将解决由一组新的微孔材料制成的膜的合成，表征和分离性能中的几个主要问题。这些结果将为MOF膜在高压下从气体混合物，特别是天然气中分离二氧化碳的实际应用奠定基础。IRMOF-1和ZIF-69膜的合成和性能研究的基础工作将扩展迄今为止专注于金属和金属氧化物材料的无机膜科学。该项目将导致开发具有良好分离性能的高性能膜，用于高压下含CO2的气体混合物。该膜的主要应用之一将是天然气净化，以生产准备在管道中运输的高压天然气。该膜将发现其他应用，如燃烧前二氧化碳捕获过程中的CO2分离，并将有助于提高工业界对应用这些新膜的许多机会的认识。MOF材料的独特性能和薄膜膜技术的结合代表了开发用于有效分离气体混合物的新膜技术的变革性方法，并将有助于确保美国在CO2捕获领域的竞争力和技术领先地位。该项目还将教育和培训研究生和本科生。特别是，女性和少数民族学生将接受培训，成为膜科学和分离技术的领导者。ASU无机膜和膜分离过程的研究生课程将结合这些基于MOF的气体分离装置的成功开发所带来的扩展观点。该项目还将包括建立一个实验室示范单位，使用膜分离二氧化碳的高中教师和学生作为亚利桑那州州立大学的“科学的乐趣”推广计划的一部分。

1160084LinMetal-organic-frameworks (MOF) represent a new group of microporous materials as membranes for gas and liquid separation applications. However, several fundamental issues unique for MOF membranes such as synthesis of thin MOF membranes and effects of adsorption induced structural change and thermal gradient on membrane separation properties have not been studied, and the unique separation properties of MOF membranes unattainable by traditional microporous inorganic membranes have not been explored for practical applications. This project is directed toward synthesis and characterization of thin, high flux microporous IRMOF-1 and ZIF-69 membranes and to study permeation and separation of these MOF membranes with a focus on understanding the effects of the adsorption induced structural change and thermal gradient on membrane transport properties. The study will explore the unique property of large pore MOF membranes, i.e., the carbon dioxide perm-selectivity increases with pressure for high pressure separation of carbon dioxide from natural gas. All existing membranes exhibit a decreasing perm-selectivity with increasing pressure. The work includes developing synthesis methods for preparation of thin (less than 5 ìm) large pore MOF membranes, identifying an adequate method for characterizing the quality of the MOF membranes, studying the permeation and separation properties of the MOF membranes at high pressures, and investigating adsorption induced structural change and thermal gradient on membrane characteristics. The membranes will be prepared by the secondary growth method with nano-sized MOF crystal seeds. A molecular probing method will be developed to examine the quality of the MOF membranes. Gas permeation of carbon dioxide, methane, nitrogen and hydrogen and separation properties of binary mixtures of these gases, particularly carbon dioxide/methane, for the IRMOF-1 and ZIF-69 membranes will be studied in a large pressure range (1-70 atm.) at 25-150C and compared with the results of modeling and molecular simulations. Structural changes and thermal gradient across the membranes during gas permeation will be studied and correlated to the gas permeation and separation properties of the membranes. The research conducted in this project will be transformational as it will address several major issues in synthesis, characterization and separation properties of membranes made from a new group of microporous materials. The results will be the basis for practical use of MOF membranes for separation of carbon dioxide from gas mixtures, in particularly natural gas, at high pressures. The fundamental work on synthesis and property study of IRMOF-1 and ZIF-69 membranes will expand inorganic membrane science which has so far been focused on metallic and metal oxide materials. The project will result in development of high performance membranes with good separation properties for gas mixtures containing CO2 at high pressures. One of the major applications of the membranes will be for natural gas purification to produce high pressure natural gas that is ready for transport in pipelines. The membranes will find other applications such as CO2 separation in pre-combustion carbon dioxide capture processes and will serve to increase industry's awareness of the many opportunities that exist for applying these new membranes. The combination of the unique properties of the MOF materials and thin film membrane technology represents a transformational approach to development of new membrane technologies for efficient separation of gas mixtures and will contribute to ensuring US competitiveness and technological lead in the area of CO2 capture. The project will also educate and train graduate and undergraduate students. In particular, female and minority students will be trained to become leaders in membrane science and separation technologies. An ASU graduate course in Inorganic Membranes and Membrane Separation Processes will incorporate the expanded perspectives resulting from the successful development of these MOF based gas separation devices. The project will also include the establishment of a laboratory demonstration unit using membranes for carbon dioxide separation for high school teachers and students as part of Arizona State University's "Science for Fun" outreach program.