Collaborative Research: Towards a Generalized Microkinetic Description of Lignin Liquefaction

木质素是一种丰富的自然资源，与纤维素和半纤维素相比，其碳含量更高，是一种非常有吸引力的可再生燃料和化学品原料。木质素液化是一种很有前途的过程，可以将这种未被充分利用的资源转化为单体酚，这些单体酚可以很容易地升级为燃料和化学品，但其潜在的化学动力学过程尚不清楚。这一合作研究项目旨在开发一个合理的框架，集成建模和实验工具，在有或没有溶剂的相关液化条件下明确解释木质素及其低聚中间体化学结构。木质素液化可以在水环境(水热液化)、有机溶剂(溶剂化)、离子液体或无溶剂条件(热解)中进行。给木质素及其低聚中间体分配一个真实的化学式是合理描述和控制木质素液化反应的主要挑战之一。溶剂和添加剂影响液化反应的机理也知之甚少。正因为如此，木质素液化仍然是一门艺术，而不是一门科学。本项目的主要目标是在描述木质素液化过程中解聚和再聚合反应以及中间产物去除机理的详细微观动力学模型的基础上，开发合理的微观动力学框架。实际的目标是利用这个数学模型和实验工具来确定合适的木质素在溶剂和酸碱催化剂存在下的液化策略，以最大限度地提高单酚的产量，从而促进现有基础设施中生物油的进一步升级。除了培训两名研究生外，首席研究人员还计划通过西北大学的暑期研究机会计划和太平洋西北路易斯·斯托克斯少数民族参与联盟，在他们的实验室接待女性和代表性较低的少数族裔高中生作为暑期研究实习生。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Lignin is an abundant natural resource whose higher carbon content, when compared to cellulose and hemicellulose, makes it a very attractive renewable feedstock for producing fuels and chemicals. Lignin liquefaction is a promising process for converting this underutilized resource into monomeric phenols that can be easily upgraded to fuels and chemicals, but the underlying chemical kinetic processes are not well understood. This collaborative research project aims to develop a rational framework that integrates modelling and experimental tools to explicitly account for lignin and its oligomeric intermediate chemical structures at relevant liquefaction conditions in the presence or absence of solvents.Lignin liquefaction can be conducted in aqueous environments (hydrothermal liquefaction), in organic solvents (solvolysis), in ionic liquids or in solvent free conditions (pyrolysis). Assigning a realistic chemical formula to lignin and its oligomeric intermediates is one of the major challenges to rationally describe and control lignin liquefaction reactions. The mechanisms by which solvents and additives impact liquefaction reactions are also poorly understood. Because of this, lignin liquefaction remains an art rather than a science. The main goal of this project is to develop a rational micro-kinetic framework based on detailed micro-kinetic models describing depolymerization and repolymerization reactions and intermediate products removal mechanisms during lignin liquefaction. The practical goal is to use this mathematical model and experimental tools to identify suitable lignin liquefaction strategies in the presence of solvents and acid-base catalysts to maximize mono-phenol production which will facilitate further bio-oil upgrading in existing infrastructure. In addition to training two graduate students the principal investigators plan to host female and underrepresented minority high school students in their laboratories as summer research interns through the Summer Research Opportunity Program at Northwestern University and the Pacific Northwest Louis Stokes Alliance for Minority Participation.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.