ABSTRACT

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.

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