木质纤维混合生物质高温水热共解聚及其强化机制

Blended lignocellulosic biomass owns the characteristic of stable supply and low cost of collection, and its bio-refinery would realize the sustainable development of fuel ethanol production. The heterogeneity and recalcitrance of blended materials limit its conversion efficiency of ethanol. Depolymerization and saccharification of biomass are the basis of cellulosic ethanol production. The good sugars accumulation in the hydrothermal conditions would help the co-depolymerization of hemicellulose, but its lignin removal and mass transfer are unsatisfied. Understanding the structure-properties relationship of biomass blending and building the efficient hydrothermal co-depolymerization system would overcome the above bottlenecks. . In this proposal, the models of blended lignocellulosic biomass are set up based on our previous works firstly, and then a synergistic or antagonistic effect of chemical compositions and structures on the depolymerization of polysaccharides and heat/mass transfer under different hydrothermal conditions will be investigated to guide the blending of different single biomass with the help of multi-scale characterization. Moreover, a novel polyhydrogen-bonding ionic liquid analogous system is developed in situ based on the property of autohydrolysis of biomass in the hydrothermal conditions, there one-pot autocatalysis-dissolution of biomass occurs. And the depolymerization mechanisms of blended biomass under the combined system of hydrothermal and ionic liquid analogous will be explained after comparing the mode of chemical bonds breaking and interfacial mass transferring at the single hydrothermal system. Furthermore, the progress of hydrothermal co-depolymerization will be further controlled after combining the analysis of substrate structures suitable for co-digestion and evaluation of energy efficiency during ethanol fermentation process. Overall, the related research in this proposal would provide insight into the industrialization of hydrothermal co-depolymerization technology in the area of bio-ethanol production from blended biomass.

木质纤维混合生物质供应稳定、收储运成本低，其乙醇炼制有利于燃料乙醇产业可持续发展，但组成结构不均一限制了其转化效率。生物质解聚糖化是其乙醇发酵的前提，高温水热过程温和、糖产物累积而有助于混合原料半纤维素共解聚，但其木质素脱除及过程传质不理想，明晰生物质混合的构效关系、构建高效水热共解聚体系，必将为解决上述瓶颈问题提供突破口。. 本项目拟在已有工作基础上，组建混合生物质模型物，从微观和宏观结合角度入手，多尺度研究混合生物质组成结构对其多糖水热解聚、热质传递的干扰和促进机制，获得多原料混合配比依据；进一步依据高温水热自催化特性，原位构建新型多氢键类离子液体强化体系，实现生物质“一锅法”水热自催化-溶解功能；对照单一高温水热过程断键及界面反应方式，阐明类离子液体参与的水热解聚机制；关联纤维素共酶解底物结构特征解析及乙醇发酵能效计算，深度掌控高温水热共解聚尺度，为该技术的实际应用提供理论基础。

木质纤维混合原料供应稳定、收储运成本低，其乙醇炼制有利于燃料乙醇产业可持续发展，但物料不均一性降低了其转化效率，构建混合生物质高效共解聚糖化体系、明晰其强化机制，是其乙醇炼制迫切需要解决的问题。本项目围绕多原料混合、半纤维素共解聚、木质素共溶、纤维素共酶解发酵展开研究。首先选取物种不同但木质素含量相近的原料羊蹄甲树枝、稻草秆和甘蔗渣，基于JMP最小二乘法构建混料模型预测不同原料混合比例的解聚效果。并以木质化程度差异性较大的玉米芯、甘蔗渣和松木作为混合原料，考察不同水热环境下混料类型对多糖解聚的影响，与单一原料相比，混合原料的耐水热缓存能力更强，混料孔径分布和颗粒形态更有利于反应传热传质。混料玉米芯/甘蔗渣（质量比2:1）的半纤维素解聚反应活化能和焓变较单一玉米芯更小、解聚反应更容易进行，混合原料递次水解的生成产物存在反馈抑制等相互影响。设计木质素衍生类离子液体（氯化胆碱/对香豆酸）与水热协同作用，将原料半纤维素和木质素共溶解脱除，纤维素酶解率达到99.36%。借助SEM、FT-IR、X射线三维显微镜表征分析发现，解聚渣表面变得粗糙，孔隙率增加了31.39%，比表面积增加了19.82%，细胞壁厚度减少了25.84%，这些变化均有利于纤维素酶与底物的接触反应，其中玉米芯/甘蔗渣（质量比2:1）混料解聚渣的纤维素基乙醇得率较未处理混料提高了1.75倍。此外，对于添加富氮构树的混合原料，其水热解聚残渣纤维素酶解发酵产乙醇、解聚液培育小球藻与粘红酵母，可以实现原料多组分全利用，相关研究为混合生物质水热共炼制提供了理论依据和科学导向。项目执行期间共发表论文19篇，其中SCI收录18篇，授权发明专利8件，参编中英文专著2部，项目负责人获批广东省杰出青年基金项目。