Key Laboratory of Green Chemistry and Technology Ministry of Education College of Chemistry, Sichuan University Chengdu, Sichuan, 610064, P. R. China.
ChemistryOpen. 2023 Feb;12(2):e202200247. doi: 10.1002/open.202200247.
The conversion of biomass faces the challenge of mass and heat transfer, as well as the exertion of heterogeneous catalyst, because raw biomass exists usually in solid state. In this work, the simultaneous transformation and dissolution of the three main components (hemicellulose, cellulose, lignin) in corn straw were achieved in ethanol/ valerolactone (GVL)/H O (10 : 10 : 40, v/v/v) co-solvent system. With the assistance of AlCl ⋅ 6H O, the conversion of hemicellulose, lignin and cellulose was >96 % at 170 °C. The conversion of solid biomass into fluid, overcoming the mass transfer restrictions between solid biomass and solid catalysts, provides new raw materials to further upgrading. H O could penetrate inside the crystalline cellulose to swell even dissolve it, while ethanol and GVL acted as media to dissolve especially the G unit in lignin. The H derived from AlCl ⋅ 6H O hydrolysis could break the linkages of lignin-hemicellulose and glycosidic bond in saccharides, and aluminum chloride promoted the next degradation of polysaccharides to small molecules. Consequently, as high as 33.2 % yield of levulinic acid and 42.2 % yield of furfural were obtained. The cleavage of β-O-4 and C -C bonds in lignin produced large amounts of lignin-derived dimers and trimers. The total yield of monomeric phenols is up to 8 %.
生物质的转化面临着传质传热的挑战，以及多相催化剂的作用，因为原料生物质通常处于固态。在这项工作中，通过在乙醇/戊内酯（GVL）/H O（10：10：40，v/v/v）共溶剂体系中，同时实现了玉米秸秆中三种主要成分（半纤维素、纤维素、木质素）的转化和溶解。在 AlCl ⋅ ⁇ 6H O 的辅助下，半纤维素、木质素和纤维素的转化率在 170°C 时超过 96%。将固体生物质转化为流体，克服了固体生物质和固体催化剂之间的传质限制，为进一步升级提供了新的原料。H O 可以渗透到结晶纤维素内部使其溶胀甚至溶解，而乙醇和 GVL 则作为溶解介质，尤其溶解木质素中的 G 单元。AlCl ⋅ ⁇ 6H O 水解产生的 H 可以切断木质素-半纤维素的连接以及糖甙键，而氯化铝则促进了多糖向小分子的进一步降解。因此，得到了高达 33.2%的乙酰丙酸和 42.2%的糠醛收率。木质素中β-O-4 和 C -C 键的断裂产生了大量的木质素衍生的二聚体和三聚体。单体酚的总收率高达 8%。
