木质纤维素催化转化制高附加值化学品乙醇酸甲酯

Methyl glycolate (MG) is widely used in chemical, pharmaceutical and agrochemical industries. In particular, MG can be used as an intermediate for production of ethylene glycol and ethanol via hydrogenation reactions. Presently, the production of MG heavily relies on the fossil resources, which will cause serious concerns about CO2 emissions. In this project, we propose a new production method for MG, that is, “one-pot” production of MG from renewable lignocellulosic biomass. To this end, three sequential reactions involved in the one-pot process, including alcoholysis of cellulose, retro-aldol condensation of sugars, and esterification of glycolaldehyde are required to match with each other in their reaction rates. Supercritical methanol will be used as the solvent and a series of early transition metal oxides will be explored as the catalysts for the selective C-C cleavage of cellulose-derived sugars (i.e., retro-aldol condensation reaction of sugars). It is expected that a high yield of MG will be achieved through optimization of the reaction conditions and catalyst formulations. For practical applications, this project will lay the basis on the further transformation of MG to ethylene glycol and ethanol. In fundamental science, we will employ in situ characterization technologies in combination with DFT calculations to reveal the cleavage mechanism of C-O-C and C-C bonds at molecular scale, which will contribute to the field of biomass valorization.

乙醇酸甲酯广泛应用于化工、医药、农药等领域，特别是其通过催化加氢反应可进一步制取大宗化工产品乙二醇和乙醇。但目前乙醇酸甲酯的生产主要通过化石路线。本项目创新性提出利用可再生的木质纤维素生物质资源通过催化转化“一锅”法制备高附加值化学品乙醇酸甲酯。项目将以超临界甲醇为溶剂，拟利用对纤维素糖类的反羟醛缩合反应（糖分子中C-C键选择性剪切）具有催化作用的前过渡金属氧化物为催化剂，通过优化催化剂和反应条件使得该过程所涉及的三个串联反应（即：纤维素醇解反应、反羟醛缩合反应、酯化反应）实现高效偶联，从而实现纤维素“一锅”高收率转化为乙醇酸甲酯，为乙醇酸甲酯的下游转化提供基础。基础研究方面，通过利用一系列原位表征方法，结合反应动力学和密度泛函理论计算，从分子层次阐明纤维素大分子C-O-C键和C-C键选择性活化和剪切的反应机理，从而为木质纤维素的高值化利用奠定理论基础。

乙醇酸甲酯广泛应用于化工、医药、农药等领域，特别是其通过催化加氢反应可进一步制取大宗化工产品乙二醇和乙醇。但目前乙醇酸甲酯的生产主要通过化石路线。本项目以钨基化合物为催化剂，首次在超临界甲醇中将纤维素一步转化为乙醇酸甲酯。对催化剂和反应条件进行详细的考察后，发现性能最优的催化剂为W2C/CMK-3，在优化的反应条件下(1MPa O2，240 oC，2 h)获得了51.2%的乙醇酸甲酯收率，且催化剂表现出较好的循环稳定性，使用6次后乙醇酸甲酯的收率仍大于50%。从而开发了一条全新的通过生物质获得精细化学品乙醇酸甲酯的高效转化路线。