Joint Bioenergy Institute, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Emeryville, CA, USA.
Biotechnol Biofuels. 2013 Jan 28;6(1):14. doi: 10.1186/1754-6834-6-14.
Lignin is often overlooked in the valorization of lignocellulosic biomass, but lignin-based materials and chemicals represent potential value-added products for biorefineries that could significantly improve the economics of a biorefinery. Fluctuating crude oil prices and changing fuel specifications are some of the driving factors to develop new technologies that could be used to convert polymeric lignin into low molecular weight lignin and or monomeric aromatic feedstocks to assist in the displacement of the current products associated with the conversion of a whole barrel of oil. We present an approach to produce these chemicals based on the selective breakdown of lignin during ionic liquid pretreatment.
The lignin breakdown products generated are found to be dependent on the starting biomass, and significant levels were generated on dissolution at 160°C for 6 hrs. Guaiacol was produced on dissolution of biomass and technical lignins. Vanillin was produced on dissolution of kraft lignin and eucalytpus. Syringol and allyl guaiacol were the major products observed on dissolution of switchgrass and pine, respectively, whereas syringol and allyl syringol were obtained by dissolution of eucalyptus. Furthermore, it was observed that different lignin-derived products could be generated by tuning the process conditions.
We have developed an ionic liquid based process that depolymerizes lignin and converts the low molecular weight lignin fractions into a variety of renewable chemicals from biomass. The generated chemicals (phenols, guaiacols, syringols, eugenol, catechols), their oxidized products (vanillin, vanillic acid, syringaldehyde) and their easily derivatized hydrocarbons (benzene, toluene, xylene, styrene, biphenyls and cyclohexane) already have relatively high market value as commodity and specialty chemicals, green building materials, nylons, and resins.
木质素在木质纤维素生物质的增值过程中经常被忽视，但木质素基材料和化学品代表了生物精炼厂潜在的增值产品，可显著提高生物精炼厂的经济效益。波动的原油价格和不断变化的燃料规格是开发新技术的一些驱动因素，这些新技术可用于将聚合木质素转化为低分子量木质素和/或单体芳香原料，以帮助替代与整桶油转化相关的当前产品。我们提出了一种基于离子液体预处理过程中木质素选择性断裂来生产这些化学品的方法。
发现生成的木质素断裂产物取决于起始生物质，并且在 160°C 下溶解 6 小时会产生大量产物。溶解生物质和技术木质素会产生愈创木酚。溶解硫酸盐木质素和桉树会产生香草醛。溶解柳枝稷和松树时，主要产物为丁香醇和烯丙基愈创木酚，而溶解桉树时，主要产物为丁香醇和烯丙基丁香酚。此外，通过调整工艺条件，可以生成不同的木质素衍生产品。
我们已经开发了一种基于离子液体的工艺，该工艺可使木质素解聚，并将低分子量木质素馏分转化为各种来自生物质的可再生化学品。生成的化学品（酚类、愈创木酚、丁香酚、丁香醛、儿茶酚）、它们的氧化产物（香草醛、香草酸、丁香醛）及其易于衍生的碳氢化合物（苯、甲苯、二甲苯、苯乙烯、联苯和环己烷）已经作为商品和特种化学品、绿色建筑材料、尼龙和树脂具有相对较高的市场价值。
