First-principles based catalyst and solvent design for the selective conversion of biomass to platform chemicals

加拿大拥有巨大的木质纤维素生物质资源，可以作为碳的替代来源，而不会对人口的营养需求造成任何压力。为了将生物质转化为增值燃料和化学品，需要将其转化为可以整合到现有工业基础设施中的所需平台中间体。生物质的液相催化处理是其选择性转化的唯一非生物热化学途径。然而，溶剂系统的筛选和选择是一个挑战，因为溶剂不仅是良性溶剂化介质，而且它们会改变转化率和选择性。此外，需要最小化胡敏素的形成以减少碳损失和催化剂失活，胡敏素是生物质反应中的不溶性缩合和聚合副产物。** 因此，拟议项目的目的是从根本上了解溶剂在生物质反应中的作用以及胡敏素及其前体形成的化学过程。具体目标包括调查溶剂的作用（I）在修改的吸附配置和能量的生物质部分的催化剂上，（II）在改变反应动力学由于不同的相对稳定的反应物和过渡态，由于溶剂动力学和非平衡溶剂化。此外，胡敏素及其前体的形成的催化反应机制将被确定和溶剂系统和促进胡敏素形成的催化剂功能将被揭示。基于对该项目的基本理解，将提出溶剂、催化剂和操作条件的最佳组合。该项目将是液相生物质转化的第一个协同研究，结合溶剂效应，反应机理和胡敏素的形成。** 基于第一原理的坚实基础的多尺度分子建模方法将在该项目中与实验协同实施。初步筛选将使用密度泛函理论中的隐式溶剂化模型进行，并将在量子力学处理的显式溶剂分子中进行选定的计算。从头算分子动力学沿着偏置方法，如metadhesics将实施调查溶剂的影响。首席研究员具有相关的专业知识和跟踪记录，以确保项目的成功。该项目将培养三名博士生和五名本科生。

Canada has huge lignocellulosic biomass resources that can be utilized as an alternate source of carbon, without putting any stress on the nutritional needs of the population. To convert the biomass to value-added fuels and chemicals, it needs to be transformed into desired platform intermediates that can be integrated into the existing industrial infrastructure. Liquid phase catalytic processing of biomass is the only non-biological, thermochemical pathway for its selective conversion. However, screening and selection of solvent systems is a challenge, since solvents are not only benign solvation media but they alter the conversion and selectivity. Additionally, the formation of humins, which are insoluble condensation and polymerization by-products in biomass reactions, needs to be minimized to reduce carbon loss and catalyst deactivation. ******Hence, the proposed project aims to develop fundamental understanding of the role of solvent in biomass reactions and of the chemistry of the formation of humins and their precursors. Specific objectives include investigating the role of solvents (I) in modifying the adsorption configuration and energies of biomass moieties on the catalyst, (II) in altering reaction kinetics due to different relative stabilization of reactants and transition states and due to solvent dynamics and non-equilibrium solvation. Additionally, catalytic reaction mechanisms of the formation of humins and their precursors will be identified and solvent systems and catalyst functionalities promoting humins formation will be revealed. Based on the fundamental understanding developed in the project, optimum combination of solvent, catalysts and operating conditions will be proposed. The proposed project will be the first synergistic investigation in liquid phase biomass conversion, combining solvent effects, reaction mechanisms and humins formation. ******A multiscale molecular modeling approach, based on the solid foundations of first principles, will be implemented in the project, in synergy with experiments. Preliminary screening will be done using implicit solvation model in density functional theory and selected calculations will be performed in explicit solvent molecules, treated quantum mechanically. Ab initio molecular dynamics along with biasing methods like metadynamics will be implemented to investigate solvent effects. The principal investigator has the relevant expertise and track record to ensure the success of the project. Three PhD students and five undergraduate students will be trained in the project.