Metal-organic framework (MOF) materials are at an emerging stage in their development as a large class of nanoporous materials for new applications especially in separations and catalysis. The central theme of this project is to create a systematic computational and experimental framework for understanding the interactions of MOF materials with hydrogen-bonding (polar) molecules. The PIs propose a synergistic experimental and modeling effort to quantitatively measure the adsorption and diffusion properties of water and alcohols (methanol and ethanol) in MOFs. Molecular adsorption and diffusion will be measured directly using state-of-the-art vapor phase gravimetry and high-gradient-strength pulsed field gradient nuclear magnetic resonance (PFG-NMR) methods with a series of MOFs chosen to systematically vary pore size and functionality. These measurements will significantly expand the scope of quantitative experimental information that is available about hydrogen-bonding molecule transport and adsorption in MOFs. By directly comparing our experimental results with a careful series of molecular simulations, the PIs expect to understand the key features of hydrogen-bonded adsorption and diffusion in MOFs and assess the capability of force fields for describing such species. In addition to extensive proposed work with established MOFs, the PIs will also study the performance of hybrid zeolitic imidazolate framework (ZIFs), a class of MOF materials developed recently at Georgia Tech. Hybrid ZIFs can be made with continuously tunable pore characteristics and create new opportunities for optimizing material performance in separations. The PIs will examine the possibility of using this fine tuning property to develop high performance membranes for water-alcohol separations. Broader Impacts. The emergence of a rational framework for evaluating MOFs in liquid-phase separations will have long-term impact in the pursuit of applications for MOFs in biofuel processing and biorefinery operations. A nearer-term technological impact could be in the successful selection and use of robust MOFs/ZIFs to create high-performance membranes for water-alcohol separations relevant in biofuel processing. At a more fundamental level, this work will advance the shared goals of the separations, porous materials, and computational chemical engineering communities in overcoming basic challenges inherent in high-throughput discovery of advanced materials for separations. This works is potentially transformative in helping to enhance the role of porous materials in chemical separations through rational design methods. The PIs will pursue these desired impacts by creating a positive and measurable impact on the careers of young and prospective engineers and scientists. The PIs will mentor a diverse group of 6-8 researchers at graduate, undergraduate, and high school levels via carefully designed and assessed learning experiences over periods of 1-3 years. This will encompass PhD thesis projects, undergraduate research projects, and extended high-school student internships in collaboration with a STEM-focused charter school. The transfer of research findings into the PIs? elective courses on nanoscale chemical engineering and molecular modeling will have a significant educational impact.
