GOALI: Tuning Renewable Solvent Systems for Lignin Purification and Fractionation

1403873 ThiesGOALI：调整用于木质素提纯和分级的可再生溶剂系统木质素是地球上最常见的有机化合物之一，约占所有有机碳的30%。木质素在生物聚合物中也是独一无二的，因为它具有显著的芳香性，这使得它具有潜在的广泛用途，包括涂料和碳纤维。不幸的是，由于其高金属(主要是钠)和灰分含量，目前可用的商业级木质素在其应用中受到严重限制。因此，在这5000万吨/年的可用木质素中，只有不到0.2%被回收。显然，如果木质素要发挥其作为生物聚合物的潜力，就必须设计出具有成本效益的分离工艺，以显著提高当今商业木质素的纯度。这种超纯木质素将对生产高价值产品非常有兴趣，例如汽车应用的碳纤维(大幅降低燃料消耗)。克莱姆森公司的研究人员发现了一种功能强大、用途广泛且可再生的热溶剂系统，该系统可以在一步内将硫酸盐法制浆过程中木质素的钠含量降低100倍至150ppm。此外，初步证据表明，通过在溶剂系统中加入压缩的二氧化碳，超纯木质素可以被分馏成确定的相对分子质量和化学组成的切片。对这些现象进行基础研究，为未来的商业应用奠定基础，是这项工作的首要目标。研究计划如下：(1)测定含木质素溶剂体系的高温液液相平衡行为。富木素和富溶剂相的相界、各相中的溶剂组成以及温度的影响将是这些测量的重点。(2)测定金属盐在上述两个相中木质素之间的分配。(3)研究了在木质素-溶剂体系中加入CO2对超纯木质素进行相对分子质量分级的影响。(4)用酚酸和羧酸的含量表征各阶段的木素成分。(5)评价超纯木质素作为石油衍生聚合物替代品在涂料中的应用。工业合作伙伴将把木质素用于不同的聚合物涂层应用。

1403873 ThiesGOALI: Tuning Renewable Solvent Systems for Lignin Purification and FractionationLignin is one of the most common organic compounds on earth, comprising about 30% of all organic carbon. Lignin is also unique among biopolymers in having significant aromatic character, which makes it potentially attractive for a wide range of uses, including coatings and carbon fibers. Unfortunately, the commercial-grade lignins available today are severely limited in their applications because of their high metals (primarily sodium) and ash content. Thus, less than 0.2% of these 50 million tons/yr of available lignin is being recovered. Clearly, cost-effective separations processes must be devised to dramatically improve the purities of today's commercial lignins, if lignin is to achieve its potential as a biopolymer. Such an ultrapure lignin would be of great interest for the production of high-value products, such as carbon fibers for automobile applications (for large reductions in fuel consumption). Clemson researchers have discovered a powerful, versatile, yet renewable hot solvent system that can be "tuned" to reduce the sodium content of lignin derived from the Kraft pulping process 100-fold down to 150 ppm in a single step. Furthermore, preliminary evidence indicates that by incorporating compressed CO2 into the solvent system, the ultrapure lignin can be fractionated into cuts of well-defined molecular weight and chemical composition. A fundamental investigation of these phenomena, in order to lay the groundwork for future commercial application, is the overarching objective of this work. The research plan is as follows: (1) Measure elevated-temperature, liquid-liquid equilibrium phase behavior for the solvent system with lignin. Phase boundaries for the lignin-rich and solvent-rich phases, solvent compositions in each phase, and the effect of temperature will be the focus of these measurements. (2) Determine the distribution of metal salts between the lignin present in the above two phases. (3) Investigate the addition of CO2 to the lignin-solvent system for fractionating ultrapure lignin by molecular weight. (4) Characterize the lignin constituents in each phase in terms of phenolic and carboxylic acid content. (5) Evaluate ultrapure lignins as replacements for petroleum-derived polymers in coatings applications. The industrial partner will use the lignin for different polymer coating applications.