双相体系中生物质基γ-戊内酯的绿色高效制备方法

γ-valerolactone (GVL) is a new biomass based platform chemical which rises in recent years. From GVL, various liquid fuels and chemicals can be produced. Focusing on the problems such as low effiency and difficulty to recycle acid catalysts in the one-pot preparation of GVL from the upstream feedstock such as cellulose, this project will employ the extraction of levulinic acid and formic acid from the aqueous phase to the GVL phase during the reaction in water-GVL biphasic system, and the consumption of levulinic acid and formic acid in GVL phase, to improve the yield of levulinic acid in aqueous phase due to the change in aqueous reaction equilibrium, and then increase the overall yield of GVL and utilization rate of formic acid. Moreover, the acid solution can be recycled after reaction. With the establishment and evaluation of catalysis system of Lewis acid-Bronsted acid-hydrophobic metal supported catalyst, the yield and selectivity of GVL will be further improved. After that, the studies on product distribution, reaction pathway, different reaction conditions, reaction kinetics of GVL preparation from cellulose and model compounds in biphasic system will be carried out. The regularities and mechanisms of GVL catalytic preparation from cellulose will be revealed. A new approach of one-pot preparation of cellulose in biphasic system will be established. The research work will promote the industrial progress of green and efficient preparation of GVL.

γ-valerolactone (GVL）是近年兴起的一个新生物质基平台化合物,由GVL出发可以制备多种液体燃料和化工产品。针对目前纤维素等上游原料一步法制备GVL技术中催化效率不高、酸催化剂难以回收等问题，本项目拟利用水-GVL双相体系的GVL相在反应过程中对水相中乙酰丙酸和甲酸的不断提取及GVL相中乙酰丙酸和甲酸的不断消耗，改变水相中反应的平衡以提高乙酰丙酸的产率，进而提高一步法制备GVL的最终产率和甲酸利用率，而且反应后的酸溶液可回收。并拟通过Lewis酸-Bronsted酸-疏水型金属负载催化剂催化体系的构建和评价，进一步提高GVL的产率和选择性，开展双相体系中纤维素及模型物质制备GVL的产物分布、反应途径、不同反应条件、动力学等方面的研究，揭示纤维素催化制备GVL的反应规律性和机理，进而建立双相体系中纤维素一步法制备GVL的新方法，推动GVL绿色、高效制备的工业化进程。

γ-戊内酯是近年来兴起的重要生物制基平台化合物，可以通过世界上存量最大的生物质—纤维素催化制备得到。以γ-戊内酯为中间产物，可制备烷烃等液体燃料，从路线上解决纤维素到液体燃料的转化问题。本项目首先以乙酰丙酸为原料，开展了催化制备γ-戊内酯的研究，以催化剂的制备为基础，构建了三个催化体系：Ni/ZrO2催化制备γ-戊内酯、Ni/Al2O3催化制备γ-戊内酯、Ni/MgO-Al2O3催化制备γ-戊内酯。在二氧六环作为溶剂中，40% Ni/MgO-Al2O3 (Mg:Al=1:1)催化效果最好，反应条件最为温和，在160 °C下催化原料反应1 h，乙酰丙酸转化率即可达到100%，γ-戊内酯选择性在99%以上。在实现了从乙酰丙酸到γ-戊内酯的高效制备后，研究了水热条件下纤维素及六元糖在离子液体催化下降解制备乙酰丙酸，并对反应动力学进行了研究，阐明了离子液体催化降解反应的催化机理和反应规律。当使用1-磺酸丁基-3-甲基咪唑硫酸氢盐为催化剂时，乙酰丙酸最高收率为56%，该离子液体结构稳定，可以回收重复使用。通过本项目的研究，制备了高催化活性、高稳定性的催化剂，考评了催化剂的催化活性，优化了γ-戊内酯制备的反应条件，成功研发了在较为温和的反应条件下γ-戊内酯的催化制备技术，并阐明其催化机理和反应规律，并研究了多反应之间的耦合机制，建立了从纤维素出发高效制备γ-戊内酯的方法，为从生物质出发制备γ-戊内酯的工业化进程提供了理论依据和实验基础。本项目共发表标注期刊论文14篇，其中SCI论文10篇，EI论文2篇；标注国内外会议论文5篇；相关发明专利授权4项，申请3项，培养毕业博士生1名，硕士生4名。