Morphology-Controlled Carbon Molecular Sieve Membranes for Gas Separation

能源工业，包括石油和天然气设施、石化生产和发电，都会产生废气流。这些气流是热的、高压的，并且可能含有有毒的化学物质。在气体可以安全地释放到大气中之前，必须有选择地从气体流中去除化学性质相似的小分子，以满足政府的监管标准。传统的气体分离技术，如低温蒸馏和吸收，是能源密集型的，因此增加了操作成本，进一步加重了环境负担。膜基分离技术是一种极具竞争力的气体分离替代技术，但在工业气体服务中使用的膜基分离技术可以从性能改进中获益，使其能够在更高的温度下使用。该项目将建立一种可控的膜制造工艺，克服膜在气体分离工业应用中面临的主要限制，包括控制孔隙内部网络和材料老化的能力。该制造工艺将聚合物前体和多孔液体结合在一起，形成对目标分子具有高选择性（偏好）和良好机械性能的“混合基质”膜。加入的材料显著提高了膜在较高温度下的工作能力，使其与能源密集型分离方法相比更具竞争力。该项目的研究结果有望广泛应用于多种气体分离工艺，并可能促进空气污染控制新技术的发展。通过研究项目为本科生和研究生提供教育机会。首席研究员还将利用密苏里科技大学现有的项目，与K-12教育工作者和高中生一起参与提高公众科学素养的活动。该项目将系统地研究最近开发的氟化共聚物（fcp）平台的结构/性质关系，该平台具有出色的气体分离性能。本研究的目的是为了更好地了解聚合物前驱体的微观结构与合成的碳分子筛（CMS）膜的物理老化和气体分离性能之间的基本关系。此类FCP材料和相关共混物具有高热稳定性和化学稳定性，因此适合在高温或恶劣化学环境下进行分离，例如天然气加工或烯烃/石蜡分离。在本项目中，研究者将通过共价键将聚合物前驱体的骨架结构与多孔有机笼（POC）纳米颗粒结合在一起，合成一系列fcp及其相关材料。探讨主链结构改性和聚合物前驱体掺杂poc对聚合物形貌、自由体积、过渡层、物理老化和气体分离性能的影响；其目的是发展这些新型膜的基本结构/性质/性能关系。纯气体的溶解度、扩散率和渗透率作为温度和压力的函数将被表征。同样，将评估所得的FCP和衍生的poc基CMS膜的混合气体渗透性能，以用于天然气或烯烃/石蜡分离。该项目将提供本科和研究生教育机会，并与密苏里科技大学现有的项目相结合，研究者将为K-12教育工作者和高中外展活动创建课堂模块。产品将通过YouTube和研究者的研究网站向公众发布。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Energy industries, including oil and gas facilities, petrochemical production, and electric power generation, produce exhaust gas streams. These gas streams are hot, high-pressure, and can contain noxious chemicals. Before the gas can be safely released to the atmosphere, small, chemically similar molecules must be selectively removed from the stream to meet government regulatory standards. Conventional gas separation technologies such as cryogenic distillation and absorption are energy-intensive and, thus, add to operational cost and further burden the environment. Membrane-based separations are a competitive alternative gas separation technology, but those used in industrial gas service stand to benefit from performance improvements that enable use at higher temperatures. This project will establish a controlled membrane fabrication process that overcomes the primary limitations facing industrial use of membranes in gas separations, including the ability to control the internal network of pores and how the material ages. The fabrication process incorporates polymer precursors and porous liquids to form a "mixed matrix" membrane with high selectivity (preference) for a target molecule and good mechanical properties. The incorporated materials significantly increase the ability of the membranes to operate at higher temperatures making them more competitive with the energy-intensive separation methods. The results of this project are expected to be broadly applicable to many types of gas separation processes and may spur the development of new technologies for air pollution control. Educational opportunities will be provided to undergraduate students and graduate students through research projects. The principal investigator will also leverage existing programs at Missouri University of Science and Technology to engage with K-12 educators and high school students in activities that enhance public science literacy. This project will systematically investigate structure/property relationships in a recently developed platform of fluorinated copolyimides (FCPs), which exhibit outstanding gas separation performance. The objective of this study is to develop a better understanding of the fundamental relationships between the microstructure of the polymer precursor and physical aging and gas separation performance of the resultant carbon molecular sieve (CMS) membrane. Such FCP materials and related blends have high thermal and chemical stability, making them suitable candidates for separations at high temperatures or in harsh chemical environments, such as natural gas processing or olefin/paraffin separation. In this project, the investigator will synthesize a family of FCPs and related materials integrating the polymer precursor’s backbone structure with porous organic cage (POC) nanoparticles via covalent bonding. The effects of backbone structure modification and polymer precursor doping with POCs on morphology, free volume, transition layer, physical aging, and gas separation properties will be explored; the objective of which is to develop fundamental structure/property/performance relationships for these novel membranes. Gas solubility, diffusivity, and permeability as a function of temperature and pressure for pure gases will be characterized. Similarly, mixed gas permeation properties over the resulting FCP and derived POC-based CMS membranes will be assessed for application in natural gas or olefin/paraffin separations. The project will offer undergraduate and graduate education opportunities, and in conjunction with existing programs at Missouri University of Science and Technology, the investigator will create classroom modules for K-12 educators and high-school outreach events. Products will be distributed to the public through YouTube and investigator's research website.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.