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

[160084]金属有机骨架（MOF）是一种新型的微孔材料，可作为气液分离膜。然而，MOF膜所特有的几个基本问题，如薄膜的合成、吸附引起的结构变化和热梯度对膜分离性能的影响等尚未得到研究，传统微孔无机膜无法达到的MOF膜的独特分离性能尚未得到实际应用的探索。本项目旨在合成和表征薄、高通量的微孔IRMOF-1和ZIF-69膜，并研究这些MOF膜的渗透和分离，重点了解吸附引起的结构变化和热梯度对膜运输性能的影响。该研究将探索大孔MOF膜的独特性质，即二氧化碳的选择性随压力的增加而增加，用于天然气中二氧化碳的高压分离。所有现有的膜都表现出随着压力的增加而降低的热选择性。主要工作包括：开发制备薄（小于5 ìm）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，研究吸附引起的膜结构变化和热梯度对膜特性的影响。利用纳米MOF晶体种子，采用二次生长法制备膜。我们将开发一种分子探针方法来检测MOF膜的质量。在25-150℃的大压力范围（1-70大气压）下，研究IRMOF-1和ZIF-69膜的二氧化碳、甲烷、氮和氢的气体渗透以及这些气体特别是二氧化碳/甲烷二元混合物的分离特性，并与模型和分子模拟的结果进行比较。研究气体渗透过程中膜上的结构变化和热梯度，并将其与膜的气体渗透和分离性能联系起来。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，表征和分离性能方面的几个主要问题。该结果将为实际应用MOF膜在高压下从气体混合物（特别是天然气）中分离二氧化碳奠定基础。IRMOF-1和ZIF-69膜的合成和性能研究的基础性工作将扩展目前以金属和金属氧化物材料为主的无机膜科学。该项目将开发出具有良好分离性能的高性能膜，用于在高压下分离含有二氧化碳的气体混合物。膜的主要应用之一将是天然气净化，以产生高压天然气，准备在管道中运输。这种膜还可以在燃烧前的二氧化碳捕获过程中进行二氧化碳分离等其他应用，并将有助于提高行业对应用这些新膜的许多机会的认识。MOF材料的独特特性和薄膜膜技术的结合代表了一种革命性的方法，用于开发有效分离气体混合物的新膜技术，并将有助于确保美国在二氧化碳捕集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被培养成为膜科学和分离技术的领导者。亚利桑那州立大学的无机膜和膜分离过程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产生的扩展视角。该项目还将包括为高中教师和学生建立一个使用膜进行二氧化碳分离的实验室演示单元，作为亚利桑那州立大学“科学乐趣”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.