溶剂热、无模板合成结构可控的介孔聚合型固体强酸及其对催化结晶纤维素解聚反应的性能研究

Acid-catalyzed production of glucose, cellobiose and HMF from depolymerization of crystalline cellulose has received considerable attention in the area of biomass transformation, and development of highly efficient solid acids plays key factor for catalyzing depolymerization of crystalline cellulose under green and low cost conditions, which was very important for the widely industrial applications of biofuels. In this application, we plan to prepare mesoporous polymeric solid strong acids with controllable structural characteristics and acidic sites, which could be synthesized from copolymerization of divinylbenzene or 1-allyl-3-vinylimidazolium with p-styrene sulfonate and 1-vinylimidazole under solvothermal conditions without using any organic templates. After treating the resultant samples with 1,3-propane sultone and ion exchanging with various strong acids, efficient mesoporous polymeric solid acids with controllable structure characteristics were obtained. We will systematically characterize the solid acids and investigate their catalytic applications for catalyzing depolymerization of crystalline cellulose into glucose, frutose and HMF in ionic liquids system, revealing the reaction mechanism, and investigating the relationship between structural properties and their catalytic performances. To further reduce the cost of biofuels and maintain high catalytic performances of these solid acids, we will partially replace the ionic liquids with green solvents such as DMSO and DMF, and adjust the structure and acidity of the solid acids. The preparation of mesoporous polymeric solid acids will overcome the low catalytic performances of conventional solid acids, and the pollution resulted from usage of mineral acids, which will be potentially important for their wide applications for catalyzing depolymerization of crystalline cellulose into biofuels through green and sustainable processes in industry.

酸催化结晶纤维素解聚制备葡萄糖、果糖、HMF等是近几年生物质转化研究的热点，开发高效固体酸是实现其绿色、低成本催化转化的关键。本申请计划在溶剂热、无模板条件下，以二乙烯基苯、烯丙基-N-乙烯基咪唑离子液体为交联剂与苯乙烯磺酸、乙烯基咪唑等为功能单体聚合，经过季胺化处理、强酸交换制备新型介孔聚合型固体强酸。合成过程中调变单体摩尔比实现对其酸中心、孔结构的有效调控，同时利用多种现代化测试技术对材料的孔结构、酸中心进行细致研究。计划以离子液体为溶剂，系统研究介孔聚合型固体酸在催化植物结晶纤维素解聚到糖类、HMF等生物平台化合物的反应机制。揭示固体酸孔结构、表面极性、酸中心等与其催化性能与产物选择性的关联性，优化反应条件。克服传统固体酸催化效率低、选择性差的缺点，避免液体酸催化剂的使用，实现微晶纤维素高活性、高选择性催化转化。合理调变反应体系，实现绿色、低成本条件下植物微晶纤维素高效催化解聚。

生物质催化转化制备生物能源是催化化学及能源化学领域的研究热点，生物能源的清洁开发及高效利用克服了传统化石能源储量有限、不可再生等难题。结晶纤维素作为天然生物质储量大、价格低廉，催化微晶纤维素解聚制备生物能源及相关精细化学品受到了广泛研究。结晶纤维素催化解聚需要在酸碱催化剂存在下，通过解聚、异构化、脱水等反应实现，均相酸碱催化剂具有优异的催化性能，然而其腐蚀性强、难分离、再生困难等限制了其广泛应用。利用固体酸碱替代均相酸碱对于实现过程绿色化、提升经济性具有重要意义，而报道的固体酸碱催化活性较差，限制了其在催化微晶纤维素解聚中的应用。本项目开发出对微晶纤维素具有高效催化转化性能的系列多孔固体酸：(i)通过调变多孔固体酸孔结构及表面浸润性强化过程传质及活性中心暴露度；(ii)调控酸中心含量、强度降低反应活化能。得到了磺酸根、强酸性离子液体等功能化的多孔聚合物、碳等固体酸，并实现其绿色、快速制备，上述固体酸温和条件下实现结晶纤维素高效催化解聚制备葡萄糖、果糖、HMF等。研究为多孔固体酸的绿色可控制备，并应用于高效催化结晶纤维解聚制备生物能源提供了技术源头。.生物能源组成较为复杂，利用过程中产生大量CO2及一定浓度硫化物气体(SO2、H2S、COS等)。CO2是典型的温室气体，硫化物气体毒性大、腐蚀性强、污染环境，其高效脱除对于我国能源安全及环境保护具有重要意义。本项目开发的多孔固体碱对CO2具有高效吸附及催化转化性能，其对硫化物气体同样表现出优异的选择性吸附性能，且温和条件下将COS、H2S直接催化转化成单质硫，克服了传统脱硫技术硫容低、能耗大及含硫尾气排放等缺点。上述研究为生物能源清洁高效利用提供了贯通式技术支撑。基于以上研究，负责人所带领的研究小组在Adv. Mater., ACS Catal., Chem. Comm., AIChE J.等期刊发表论文32篇(一区论文19篇)，申请发明专利14件(授权5件)，合作撰写专著1章。