溶胶-凝胶伴随相分离制备阶层多孔Ca12Al10Si4O35块体材料

Ca12Al10Si4O35(C12A5)is one of calcium aluminum oxides (mayenites) with zeolite-like structure. This has a unique nanoporous framework which contains superoxide anions and peroxide species. It has been expected to become an advanced catalytic and purification materials which gathers catalysis, adsorption, solidification, etc together. At present, C12A5 is mostly prepared by solid-phase reaction method, in which there exists low purity of phase composition and simple pore distribution. Based on sol-gel principle and phase separation theory, the project creatively provides an approach to fabricate hierarchically porous C12A5 bulk monoliths via sol-gel accompanied by phase separation. The research focuses on the co-hydrolysis of Ca, Al and Si multi-precursors, transition of sol into gel, phase separation induced by poly(ethylene oxide), and construction of hierarchically porous structure of C12A5 porous monoliths. The controlling mechanism of combining sol-gel transition with phase separation induction and the formation of hierarchically porous structure will be revealed. The relationship between hierarchically porous structure and active oxygen anions will be clarified. As a result, the structure with macro-(>50nm)/meso-(2-50nm)/nano-(<2nm) pores will be constructed, and the hierarchically porous C12A5 bulk monoliths will be fabricated. It will provide the theoretical basis for the preparation of mayenites with advantages like high purity, controllable pore structure and utilization of nanopores.

Ca12Al10Si4O35(C12A5)是一种结构类似沸石的钙铝石(mayenite)，具有独特的纳孔框架以及含有较多超氧离子、过氧离子等活性氧离子，有望成为集催化、吸附、固化等功能于一体的新型催化及净化材料。本课题针对C12A5固相合成存在的物相纯度不高、孔结构分布单一等问题，基于溶胶-凝胶原理和相分离理论，采用溶胶-凝胶伴随相分离制备阶层多孔C12A5块体材料，通过钙铝硅多前驱体共水解原理及溶胶-凝胶转换、聚氧化乙烯诱导相分离、阶层多孔结构构造等机理研究，揭示溶胶-凝胶转换与相分离诱导协同控制、阶层多孔结构可控构造等机制，搭建大孔(>50nm)/介孔(2-50nm)/纳孔(<2nm)的阶层多孔结构，阐明阶层多孔结构与钙铝石活性氧离子之间的内在规律，制备阶层多孔C12A5钙铝石块体材料，为钙铝石体系的高纯制备、孔结构优化及纳孔高效利用奠定重要基础。

本项目针对钙铝石固相合成存在的物相纯度不高、孔结构单一等问题，基于弗洛里-哈金斯晶格理论，以廉价无机钙、铝盐（氯盐或硝酸盐）为共同前驱体，醇水为溶剂，聚氧化乙烯PEO为相分离诱导剂，环氧丙烷PO为凝胶促进剂，乙二醇EG和甲酰胺为络合剂和干燥控制剂，采用溶胶-凝胶伴随相分离制备阶层多孔钙铝石块体材料，通过多元体系溶胶-凝胶原理、共混系统相分离协调机制、溶胶-凝胶转变与相分离诱导协同控制、超氧离子电子取代等机理研究，突破了阶层多孔结构可控构造、氧化及还原模拟计算、稀土元素掺杂等关键技术，搭建了贯通大孔（1~3um）与纳孔（0.6 nm）同时分布、孔隙率在70%以上、共连续纳米晶骨架、外观呈块体状的阶层多孔结构，分别制备含氯及不含氯阶层多孔钙铝石块体材料、多孔钙铝石导电材料和Tb掺杂多孔钙铝石发光材料，阐明了阶层多孔结构特征与块体材料物化性能、孔结构特征、光电功能特性之间的内在规律，完善了环氧化物溶胶-凝胶伴随聚合物诱导相分离制备阶层多孔块体的理论体系，所制备的系列多孔钙铝石块体材料在电化学、发光、催化、吸附等领域展现出重要的应用前景。