SGER - Fundamental Understanding of Catalytic Cleavage of Lignin in Ionic Liquids

SGER - 对离子液体中木质素催化裂解的基本了解

• 批准号: 0849342
• 负责人: John Ekerdt
• 金额: --
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0849342&HistoricalAwards=false
• 关键词: SGER; Fundamental; Understanding; Catalytic; Cleavage

0849342EkerdtIntellectual Merit Lignin is one of the major components in lignocellulosic biomass. The recalcitrant nature of lignin toward microbial breakdown is a highly beneficial feature in guarding natural forestry from rapid degradation by nature itself. Even though nature has evolved a number of enzymes that collectively are efficient in hydrolytically cleaving cellulose and hemicelluloses into their building units, the presence of lignin has been known to severely inhibit such activities. This research addresses this most pressing of issues in biomass conversion and seeks to develop processes and insight into key steps in lignin depolymerization, which are first steps in efficient biomass conversion. The research builds on previous studies and literature that demonstrate lignin can be dissolved in ionic liquids and that lignin is attacked by bases. Lignin has a complicated but poorly characterized composition and architecture, which also depend on the plant species and conditions in which the lignocellulosic biomass are produced. To avoid analytical complication for the purposes of understanding the mechanisms involved in base catalyzed hydrolysis of lignin oxygen linkages, this research will study model compounds that contain oxygen linkages found in lignin. The research investigates neutral ionic liquids and basic ionic liquids, each with an optimized amount of water, and with and without using a catalyst. The pH and the temperature of the test media will be controlled and followed. The effects of reaction time, process pressure, base catalyst type and concentration will all be examined. The research will employ aromatic alkali, of which the basicity can be tuned by the alkalinity of the metal ion, the type and the size of aromatic moiety, and polybasicity. Basic aromatic carboxylates will be included in the study to leverage their strong affinity toward lignin structure in a suitable carrier solvent, such as ionic liquids. By selecting catalysts of varying basicity and by varying operating conditions, we propose to target selectively oxygen linkages of different bond strength in different bonding networks. Broader Impacts By working with a number of model compounds that simulate the oxygen linkages in lignin, this research seeks to achieve a fundamental understanding of the mechanisms involved in lignin hydrolytic cleavage. Ionic liquid solvents that dissolve lignin will be used as media to carry out the reactions. Base catalysts with varying basicity will be used to study the effect of base strength in their activity toward the hydrolytic cleavage of oxygen linkages in ionic liquid solvents. The types of oxygen linkages in the model lignin compounds will be ranked according to their ease of cleavage in the presence of a base in ionic liquids. The knowledge to be gained through this research will help design processes for the rapid fragmentation nature of lignin in ionic liquids. Further, building upon an understanding in the hydrolytic cleavage of oxygen linkages in lignin, the model lignin compounds will be further studied in ionic liquids for selective cracking to produce aromatic molecules as potential fuels and chemicals.

0849342Ekerdt智力优点木质素是木质纤维素生物质的主要成分之一。木质素对微生物分解的顽抗性质是保护天然林业免受自然本身快速降解的非常有益的特征。尽管自然界已经进化出许多酶，它们共同有效地将纤维素和半纤维素水解成其结构单元，但已知木质素的存在会严重抑制这种活性。这项研究解决了生物质转化中最紧迫的问题，并寻求开发工艺并深入了解木质素解聚的关键步骤，这是高效生物质转化的第一步。该研究建立在先前的研究和文献的基础上，这些研究和文献证明木质素可以溶解在离子液体中并且木质素会受到碱的攻击。木质素具有复杂但特征不明的组成和结构，这也取决于植物种类和产生木质纤维素生物质的条件。为了避免分析复杂化，以了解木质素氧键碱催化水解所涉及的机制，本研究将研究含有木质素中发现的氧键的模型化合物。该研究研究了中性离子液体和碱性离子液体，每种液体都含有优化的水量，并且使用和不使用催化剂。测试介质的 pH 值和温度将受到控制和遵循。反应时间、工艺压力、碱催化剂类型和浓度的影响都将被检查。该研究将使用芳族碱，其碱度可以通过金属离子的碱度、芳族部分的类型和大小以及多碱度来调节。研究中将包括碱性芳香族羧酸盐，以利用其在合适的载体溶剂（例如离子液体）中对木质素结构的强亲和力。通过选择不同碱度的催化剂和不同的操作条件，我们建议选择性地瞄准不同键网络中不同键强度的氧键。更广泛的影响 通过使用许多模拟木质素中氧键的模型化合物，本研究旨在对木质素水解裂解的机制有一个基本的了解。溶解木质素的离子液体溶剂将用作进行反应的介质。具有不同碱度的碱催化剂将用于研究碱强度对其活性对离子液体溶剂中氧键水解断裂的影响。模型木质素化合物中的氧键类型将根据它们在离子液体中存在碱的情况下裂解的难易程度进行排序。通过这项研究获得的知识将有助于设计离子液体中木质素快速裂解性质的工艺。此外，基于对木质素中氧键水解断裂的理解，模型木质素化合物将在离子液体中进一步研究，用于选择性裂解，产生芳香族分子作为潜在的燃料和化学品。