高稳定性孔性配位聚合物在能源气体分离的研究

Recently, a new class of designable and robust porous materials, porous coordination polymers (PCPs) or metal organic frameworks (MOFs), have demonstrated significant promise for energy gas adsorption and separation because of their chemical tailorability, which results in high BET surface areas and specific recognition ability for components in the gas mixture. Because of the theoretically limitless possibilities in assembling organic linkers and metal or cluster connectors, a large number of structures have been reported,but a few of them show show outstanding storage and selectivity for small hydrocarbons. This is mainly due to their similar physical and chemical properties, which lead to the difficulty for adsorption-based separation. However, among these few structures, their rather low hydrothermal and chemical stabilities, compared with zeolites, further limit their usage in moist and chemical environments. Therefore, candidate PCPs with high separation capability and enhanced stability in air, water, and acidic and basic media for energy gas separation are urgently needed. To overcome these issues, our strategy is to employ the trivalent ion and rigid azole-carboxylic ligand with hydrophobic group to construct porous frameworks. Because of the high coordination number of metal, zeolite-framework, and also the protected coordination bond by hydrophobic group may enhance the water stability of the framework. Meanwhile, it is very important to explore the relationship between the stability and adsorption/separation performance that will influenced by the the position of the hydrophobic group, cooprative tuned pore type/size and the framework topology. Overall, our work will provide a scientic support for finding the porous materilas with independent creation.

孔性配位聚合物，以其可控的结构，较高的比表面积,特殊的认知能力等特点，受到全球范围化学家、材料学家的广泛关注，也将成为"清洁能源气体存储和低能耗混和能源气体分离"的重要平台，但是材料的水稳定性是目前尚待解决的关键难题。本项目拟基于运用唑类和多酸配体连接子，引入疏水基团和高价金属节点的策略，利用增强配位键能力和遮挡配位键等方法，从而实现控制搭建高水稳定，且兼具高分离性能的孔性配位聚合物材料。同时，系统研究不同疏水基团，配位点位置，孔洞类型和尺寸，气体扩散效率等因素与多孔材料稳定性和分离性能的关系，为制备具有自主创新的孔性材料提供科学依据和技术支持。

构建高孔性配位聚合物结构以及它们丰富可调的可接触空间是近几年材料领域的研究热点。然而像沸石分子筛那样成功的工业应用，孔性配位聚合物材料在水稳定性和孔功能性的兼容性等方面还差强人意。本课题结合前期在晶体材料设计合成方面的研究基础，通过引入唑类基团，疏水基团引入等策略，成功制备出6个稳定的孔性配位聚合物。其中，基于咪唑修饰且具有高pKa值的混合多齿配体铜配位聚合物展现出较高的孔隙率，其比表面积也达到可能工业应用的前提（1000m2/g）。重要的是，材料稳定性测试实验表明，该化合物能够保持非常好的结构完整性，即使暴露其在比较苛刻的条件，比如：60度的水和酸碱溶液（pH = 2-7）。更为重要的是，这是极其罕见的离子骨架具有高稳定性，高孔性的化合物。气体吸附分离实验，理论模拟研究表明该化合物展现出高效的天然气分离能力。另外，通过修饰疏水基团，首次发现层状二维结构的稳定性以及其疏水能力（130º）。以上两个例子的成功合成和制备为高稳定性孔性配位聚合物材料工业化的发展提供重要理论依据和科学意义。