离子液体中富纤维农林废弃物转化成能源平台分子的研究

Every year nearly 10 billion tons rich fiber agricultural and forestry waste will be formed in our country, but they can be converted into a liquid fuel or high value-added chemicals through the chemical refining. However, the supramolecular structure of cellulose has high stability and chemical properties, which greatly limits the current conversion of them into the small molecular compounds via acid hydrolysis. According to the characteristics of cellulose dissolved in ionic liquid and acidic environment degradation, this project proposes using the functional dicationic ionic liquid as solvent and catalyst to enhance the catalytic degradation of cellulose under mild conditions, by changing the structure of ILs, adjusting the acidic sites and the hydrophilic lipophilic properties. The investigation focus on the law and influence factors of the degradation of cellulose into monosaccharide and the conversion of monosaccharide dehydration to furan derivatives will be proceeded. Then the conversion of the rich fiber agricultural and forestry waste to the energy platform compounds will done after the in-depth investigation of the action and the mechanism of degradation of cellulose fiber in acidic ionic liquid..With this research project proformed, it could be clear that the dissolve and degradation behavior of cellulose in acidic ionic liquid, and the chemical refining of agricultural and forestry waste can also be explored, and then provide a reference for the processing and utilization of biomass resources.

我国每年将产生近10亿吨的富纤维农林废弃物，通过化学炼制可以定向地将其转化成液体燃料或高附加值化学品。然而，纤维素的半晶态超分子结构使其具有高稳定化学性能，极大地限制了目前酸解技术将其转化成小分子化合物。本项目拟根据纤维素在离子液体中可溶及酸性环境可降解的特性，研制双阳离子型的功能化离子液体，通过改变离子液体阴阳离子的结构，调节其酸性位点和亲水亲油性能，在温和条件下催化降解纤维素；并通过分步考查纤维素降解成单糖以及单糖脱水环合成呋喃类衍生物反应的规律及影响因素，深入研究其作用机制及纤维素降解机理，实现富纤维农林废弃物高效地转化成能源平台分子。通过本项目的研究可以深入认识纤维素在酸性离子液体中溶解和降解行为和规律，还可以探索农林废弃物的化学炼制可行性，为生物质资源加工与利用提供参考。

为了提升木质纤维素转化成能源平台分子，本项目围绕纤维素降解制备还原糖，糖类化合物脱水环合成呋喃类物质，以及糠醛精制加工成能源化合物的方面开展了相关研究。通过对生物质的表征，分析了生物质基本特性，并对生物质中各种成分进行了定量检测，为其离子液体中的高效转化提供指导；然后通过研制合成一系列功能化双咪唑离子液体，并将筛选的离子液体应用到纤维素制备能源分子的研究中。结果表明研制的双咪唑六氟磷酸型离子液体具有对称性好，结构易调，易于制备，具有绿色环保的优点；由于良好的温控特性，使其在纤维素转化，尤其是在木糖和果糖制备糠醛和羟甲基糠醛方面存在较好的潜力，可以实现单糖高转化率和呋喃类化合物的高产率的“双高”特点，其中木糖在水溶液中定向转变成糠醛的产率超过50%，果糖定向转化成5-HMF的产率80%以上。此外，通过糠醛缩合反应，制备出了C10或C13中长链能源分子，其中十三碳二醇的产率80%以上，为制备C13烃类化合物开辟新的途径，实现了项目计划中木质纤维素制备能源平台分子的预期目标。该项目成果，为生物质化学转化制备生物质能源探索了新的途径。