ZIFs杂化膜的合成与低浓度糠醛分离性能研究

Furfural is one of the important platform compounds based on biomass resources. Due to its side reaction at reaction conditions, furfural should be removed from the solution during the reaction process by steam. This leads to the final concentration of furfural that is generally low. In industry distillation technique for the separation of furfural is maturity, however, it has high energy consumption defects. Membrane separation technique can effectively reduce energy consumption. From the literature reported, the separation factor of furfural over water is high, however, the furfural flux is generally low. The separation performance of membrane materials can be improved by the preparation of mixed matrix membranes by incorporating porous materials. The research concepts of this project: the changes of hydrophobic and organophilic substituted groups in zeolitic imidazolate frameworks (ZIFs) can efficiently adjust and improve the furfural affinity selectivity of membrane materials, and the large pore volume of ZIFs by design synthesis ensures the furfural flux of membrane materials. Therefore, mixed matrix membranes were prepared for the efficient separation of furfural. This project plans to design and synthesize large pore ZIFs by using bulky amides as the structure directing agents, and the relationship between the pore structure of ZIFs and the pervaporation performance of the mixed matrix membranes will be established. At the same time, by the experiment and computer simulation the hydrophobicity/furfural affinity properties of ZIFs group will be obtained, the relationship between the type/position of the ZIFs groups and pervaporation performance of the mixed matrix membranes will be established. Through above research, ZIFs mixed matrix membranes with high performance is designed and constructed for the separation of low concentration of furfural, which will provide theoretical basis and fundamental data for industrial application.

糠醛是基于生物质资源的重要平台化合物之一。糠醛在其生成条件下容易发生副反应，需要及时移出反应体系，导致原液中糠醛浓度较低。工业上蒸馏法分离糠醛工艺成熟，但分离能耗高；膜分离能有效降低能耗，但文献报道的膜材料存在糠醛通量低的问题。通过掺杂多孔材料制备杂化膜能够有效提高膜材料的分离性能。本项目的研究思路：利用沸石咪唑酯骨架材料（ZIFs）中憎水亲有机基团变化来调节和提高膜材料对糠醛的亲和选择性，设计合成大孔容ZIFs保证膜材料糠醛通量，获得高效分离糠醛的杂化膜。计划采用大尺寸酰胺溶剂合成大孔的ZIFs，建立ZIFs孔道结构与杂化膜糠醛渗透汽化性能关系；同时通过实验和模拟计算，理解ZIFs基团的憎水/亲糠醛特性，建立ZIFs基团类型和位置变化与杂化膜糠醛渗透汽化性能的关系。通过上述关系规律的研究，设计构筑对低浓度糠醛高效分离的ZIFs杂化膜，为实际应用提供理论和基础数据的支撑。

针对生物质平台化合物糠醛原液低浓度的特点，设计合成低能耗高性能的沸石咪唑酯骨架（ZIFs）吸附剂/ZIFs杂化膜。利用支链酰胺溶剂作为模板剂/结构导向剂合成大孔ZIFs材料，建立ZIFs孔道结构与糠醛限域和传质扩散性能关系；实验和模拟结合研究ZIFs基团类型与其憎水亲糠醛性能关系；综合获取确定憎水亲糠醛的ZIFs关键孔表面和孔结构参数。通过上述关系规律的研究，制备ZIFs纳米颗粒均匀分散且糠醛渗透汽化性能优异的ZIFs杂化膜。同时拓展研究了ZIFs基多孔碳制备及糠醛吸附性能。研究结果显示：（1）通过酰胺溶剂中胺基N连接C链长度的增加结构导向实现大孔ZIFs材料的合成；（2）确定憎水亲糠醛的关键孔表面（憎水亲糠醛的烷基基团）和孔结构参数（适合糠醛限域吸附和传质扩散的孔窗尺寸）；（3）憎水性的PEBA颗粒溶解在未经干燥的大孔憎水ZIFs纳米颗粒形成的悬浮液中，制备了纳米高分散的ZIFs/PEBA杂化膜，所制备的杂化膜展示了优异的糠醛渗透汽化综合性能；（4）通过相同化学组成但不同孔结构的ZIFs制备的杂化膜对比，确定了ZIFs杂化膜优先透糠醛机理；（5）制备了大孔容憎水的ZIFs基多孔碳微孔材料，其具有高的糠醛吸附容量和耐酸稳定性。上述ZIFs分离材料的合成及性能研究为具有工业应用价值的吸附剂/杂化膜制备提供基础数据和理论支持。