Collaborative Research: Low-Energy Tandem Process for Fractionation and Reversible Preservation of Lignocellulose Using Multifunctional Aldehyde Sulfonic Acids

木质纤维素是一种很有前途的化石资源替代品，用于生产燃料，化学品和材料。然而，大多数目前的生物质分级方法面临的问题，如碳水化合物级分（纤维素纤维和半纤维素糖）的不希望的损失和木质素（芳族化合物）的显着结构变化的过程中，这两个贬值的分级组分。拟议的项目将开发一种节能，廉价和保值的生物质分馏系统使用醛磺酸。拟议研究的成功将直接影响美国基于木质纤维素的生物炼制，纸浆和造纸工业以及其他相关部门。它还将通过替代石油原料和减少分馏过程中的能源消耗，促进低碳生物经济。该项目将通过研究生和本科生培训（特别是女性和少数民族学生）和课程开发，促进生物精炼，生物能源和生物制品（3B）的STEM教育。该项目还将包括与K-12学生的外联活动，为对3B领域感兴趣的学生提供实验室图尔斯，暑期实习和研究项目。拟议的研究使用新的醛磺酸（含乙醛的芳香族磺酸）来实现木质纤维素生物质的快速和接近完全的分馏，而不需要显著的生物质尺寸减小预处理。该方法不仅使纤维素、半纤维素和木质素的产量最大化，而且相对于现有方法还降低了工艺能耗。使用基于模型的分子设计方法，将通过磺化从廉价的含芳族化合物合成具有可调结构、物理性质和反应活性的醛磺酸。机理上，醛磺酸通过磺酸基团使木质纤维素断裂，然后通过与醛基相互作用保护碳水化合物和木质素免于降解和缩合。由于其作为催化剂、溶剂和分解剂的多功能性质，预期醛磺酸在温和条件下将厘米级木质纤维素原料快速且几乎完全地分解成可裂解且可分解的木质素、纤维素和半纤维素。这项研究将测试的中心假设，醛磺酸将是更有效的和选择性比目前的无机/有机酸和醛的组合在分馏木质纤维素。将使用定量结构-性能分析开发数学模型，以预测一系列醛磺酸的结构特性和性能。通过这些建模研究，将从机理上阐明木质素和半纤维素的串联解聚和可逆保存，以了解酸不稳定键的裂解反应动力学和保护性化学基团的形成。该奖项反映了NSF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。

Lignocellulose is a promising alternative to fossil resources for the production of fuels, chemicals, and materials. However, most current biomass fractionation processes face issues such as unwanted loss of carbohydrate fractions (cellulose fibers and hemicellulose sugars) and significant structure changes of lignin (aromatic compounds) during the process, both of which devalue the fractionated components. The proposed project will develop an energy-efficient, inexpensive, and value-preserving biomass fractionation system using aldehyde sulfonic acids. The success of the proposed research will directly impact the U.S. lignocellulose-based biorefinery, pulp and paper industries, and other related sectors. It will also contribute to a low-carbon bioeconomy by replacing petroleum feedstocks and reducing energy consumption in the fractionation process. The project will promote STEM education in biorefineries, bioenergy, and bioproducts (3B) through graduate and undergraduate student training (particularly female and minority students) and curriculum development. This project will also include outreach activities with K-12 students by providing lab tours, summer practicums, and research projects for the students interested in the 3B fields. The proposed research uses novel aldehyde sulfonic acids (aldehyde-containing aromatic sulfonic acids) to accomplish a rapid and near-complete fractionation of lignocellulosic biomass without the need for significant biomass size-reduction pretreatment. This process not only maximizes the production of cellulose, hemicellulose, and lignin but it also reduces process energy consumption relative to existing methods. Using a model-based molecular design approach, aldehyde sulfonic acids with tunable structure, physical properties, and reactivity will be synthesized from inexpensive aldehyde-containing aromatics by sulfonation. Mechanistically, aldehyde sulfonic acids fractionate lignocellulose through the sulfonic acid group and then protect carbohydrates and lignin from degradation and condensation by interaction with the aldehyde group. Because of their multifunction nature as a catalyst, solvent, and preserver, aldehyde sulfonic acids are expected to fractionate centimeter-sized lignocellulose feedstocks rapidly and nearly completely under mild conditions into cleavable and upgradable lignin, cellulose, and hemicellulose. This research will test the central hypothesis that aldehyde sulfonic acid would be more effective and selective than current combinations of mineral/organic acids and aldehydes in fractionating lignocellulose. Mathematical models will be developed using quantitative structure-performance analysis to predict structural properties and performance of a range of aldehyde sulfonic acids. The tandem depolymerization and reversible preservation of lignin and hemicellulose will be mechanistically elucidated through these modeling studies to understand the cleavage reaction kinetics of the acid-labile linkages and the formation of protective chemical groups.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.