Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-forest Biomass, Nanjing Forestry University, Nanjing, Jiangsu 210042, China.
Jiangsu Co-Innovation Centre of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing, Jiangsu 210037, China.
J Agric Food Chem. 2020 Nov 25;68(47):13760-13769. doi: 10.1021/acs.jafc.0c04804. Epub 2020 Nov 16.
Levulinate is one of the high added-value biomass-derived chemicals that is primarily produced from hexoses in cellulose and hemicellulose. Producing levulinate from pentoses in hemicellulose that is extensively distributed in biomass is still highly challenging. In this study, biomass materials and carbohydrates (including cellulose, xylan, glucose, fructose, and xylose) were collaboratively converted into levulinates efficiently over various zeolites with ethanol/dimethoxymethane as cosolvents. The key process for converting pentoses into levulinates is the synthesis of intermediates (furfural) into alkoxy methyl furfural via electrophilic substitution or their conversion into furfuryl alcohol via in situ hydrogenation. The substitution was achieved by the synergic effect between bifunctional catalysts and cosolvents, which promotes conversion of furfural into alkoxy methyl furfural via the electrophilic addition of alkoxy methyl radicals. Hydrogenation of furfural into furfuryl alcohol was impelled by the cooperative process between in situ generated H-donor from alcohol solvents and zeolite catalysts. Moreover, a favorable yield of 21.05 mol % of levulinates was achieved by simultaneous and collaborative conversion of cellulose and hemicellulose with the one-pot process using ethanol/dimethoxymethane as a cosolvent and the zeolite with B and L acid sites as a catalyst.
乙酰丙酸是一种高附加值的生物质衍生化学品，主要由纤维素和半纤维素中的己糖生产。然而，从广泛存在于生物质中的半纤维素中的戊糖生产乙酰丙酸仍然极具挑战性。在这项研究中，使用乙醇/二甲氧基甲烷作为共溶剂，各种沸石将生物质材料和碳水化合物（包括纤维素、木聚糖、葡萄糖、果糖和木糖）协同转化为乙酰丙酸。将戊糖转化为乙酰丙酸的关键工艺是通过亲电取代将中间体（糠醛）合成为烷氧基甲基糠醛，或通过原位氢化将其转化为糠醇。取代是通过双功能催化剂和共溶剂的协同作用实现的，这促进了烷氧基甲基自由基的亲电加成，将糠醛转化为烷氧基甲基糠醛。糠醛加氢成糠醇是由醇溶剂原位产生的 H-供体与沸石催化剂之间的协同过程推动的。此外，通过使用乙醇/二甲氧基甲烷作为共溶剂和具有 B 和 L 酸位的沸石作为催化剂的一锅法工艺，同时协同转化纤维素和半纤维素，可获得 21.05mol%的乙酰丙酸的良好收率。
