CAREER: Unlocking Reactivity-Based Separations of Olefins using Metal-Organic Frameworks

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Chemical separations, which involve partitioning a mixture of compounds into its individual components, are critical to the industrial production of commodities such as plastics. Separations account for 15% of energy consumption in the United States alone. The development of new energy-efficient separations could greatly reduce greenhouse gas emissions, improve the sustainability of the chemical industry, and decrease the cost of everyday consumer products. Traditionally, separations are carried out based on differences in the physical properties of chemicals, such as their boiling points. Here, the investigator will develop sponge-like materials capable of separating chemicals based on their differing reactivities. This will enable industrial separations with much higher selectivities for one component over another and potentially unlock new types of separations. This project will be highly interdisciplinary, involving aspects of chemistry, chemical engineering, and materials science, which will help strengthen communication between these fields. In addition, new scientists from underrepresented communities will be trained, improving the diversity of the STEM workforce. As part of the project, the public, especially underserved students in rural communities, will learn about the importance of chemical separations, sustainability, and green technologies.Unsaturated molecules such as olefins are critical building blocks for the global production of polymers. However, polymerization reactions typically require ultrapure streams of olefins to proceed efficiently. Currently, mixtures containing olefins (including mixtures of olefins/paraffins or olefin isomers) are inefficiently separated based on small differences in their physical properties. This project seeks to separate mixtures containing olefins based on differences in their reactivities rather than physical properties. Specifically, porous crystalline materials known as metal-organic frameworks (MOF) will be designed such that they can undergo reversible cycloaddition reactions with olefins. These novel MOF systems will allow for separations to be carried out with unparalleled selectivities and for the production of ultrapure olefin product streams in an energy-efficient manner. The materials design strategy is potentially generalizable to separations involving a range of unsaturated molecules, including carbon dioxide, reflecting the versatility of this approach. The separation efficiency of the strategy will be assessed using gas adsorption analysis and breakthrough measurements. The reactivity of the adsorbents will be characterized using in situ solid-state nuclear magnetic resonance, X-ray diffraction, and Infrared spectroscopy. This interdisciplinary research program will forge new connections between chemists, chemical engineers, and materials scientists.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.