CAREER: Molten Polymers for Selective Biomass Fast Pyrolysis to Produce Value-Added Chemicals

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Biomass from plants (lignocellulosic biomass) has been recognized as a renewable replacement for fossil-derived resources (e.g. crude oil, coal, and natural gas) to produce liquid fuels and value-added chemicals. However, existing methods to convert biomass, such as fast pyrolysis (rapid thermal decomposition of biomass in the absence of oxygen), typically lead to both desired and undesired chemical products. The use of catalysts to accelerate desired chemical reaction pathways has been widely studied to address this challenge. However, the use of inhibitors to suppress undesired pathways has been rarely explored. Molten polymers are thermoplastics that melt at high temperature yet thermally degrade more slowly than biomass, making them good candidates as inhibitors in biomass conversion reactions. The goal of the proposed research project is to investigate the reaction pathways of biomass conversion in the presence of molten polymers. Pathway inhibition with molten polymers will transform existing biomass conversion technologies by selectively promoting product yields in a tunable fashion. The project will examine the ability of MPs to attenuate undesired reaction pathways via transport and intrinsic reaction mechanisms. The research involves both experimental and computational elements on the use of MPs for selectively promoting the yields of desired products in biomass fast pyrolysis via physical inhibition of product escape and chemical inhibition of reactions involving hydroxyl groups. This hypothesis is supported by preliminary results that show a significant increase in levoglucosan and furfural yields during cellulose pyrolysis in the presence of MPs. Pyrolysis experiments will be conducted on glucose-based carbohydrates microscopically mixed with MPs with controlled structures in a microreactor. The energy barriers of key pyrolysis reactions affected by the MPs will be estimated from ab initio calculations. The objective will be to reveal the fundamental mechanisms by which MPs promote product yields in biomass pyrolysis. Integration of research and education will be accomplished by engaging students through interactive teaching, experiential learning, and community outreach. This will be enabled by a game-based software tool, Biomass Conversion Visualizer (BioCon), to be created as part of this project. BioCon will serve as the primary platform for the proposed education and outreach activities and will be designed with assistive technology to broaden the participation of students with learning disabilities.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.