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

来自植物的生物质（木质纤维素生物质）已被认为是化石来源资源（如原油、煤炭和天然气）的可再生替代品，可以生产液体燃料和增值化学品。然而，现有的转化生物质的方法，如快速热解（在无氧条件下对生物质进行快速热分解），通常会产生所需和不需要的化学产物。为了解决这一挑战，人们广泛研究了使用催化剂来加速所需的化学反应途径。然而，使用抑制剂来抑制不希望的途径很少被探索。熔融聚合物是热塑性塑料，在高温下熔化，但热降解速度比生物质慢，使其成为生物质转化反应抑制剂的良好候选者。提出的研究项目的目标是研究在熔融聚合物存在下生物质转化的反应途径。熔融聚合物的途径抑制将通过选择性地以可调的方式促进产品产量来改变现有的生物质转化技术。该项目将检查MPs通过运输和内在反应机制减弱不希望的反应途径的能力。该研究包括实验和计算两个方面，通过物理抑制产物逸出和化学抑制涉及羟基的反应，利用MPs选择性地促进生物质快速热解中所需产物的产量。这一假设得到了初步结果的支持，初步结果表明，在MPs存在下，纤维素热解过程中左旋葡聚糖和糠醛的产量显著增加。热解实验将在微反应器中对葡萄糖基碳水化合物与可控结构的MPs微观混合进行。受MPs影响的关键热解反应的能垒将通过从头计算来估计。目的是揭示MPs促进生物质热解产物产量的基本机制。研究与教育的整合将通过互动教学、体验式学习和社区外展吸引学生来完成。这将通过一个基于游戏的软件工具，生物质转换可视化器（BioCon）来实现，这是该项目的一部分。BioCon将作为拟议的教育和推广活动的主要平台，并将采用辅助技术进行设计，以扩大有学习障碍的学生的参与。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。

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.