新型阴离子框架多孔材料的构筑和烯烃纯化性能的研究

Alkenes (such as ethylene and propylene) are the most produced raw materials for petrochemical production. The separation and purification of alkenes from alkanes is the most important but challenging industrial separation. Development of new porous materials with excellent separation performance for this separation can efficiently reduce energy costs of traditional cryogenic distillation methods. However, the reported materials so far are not good enough, whose performances are limited by the trade-off between selectivity and uptake capacity. This project aims to improve the selectivity and uptake capacity simultaneously in a single inorganic-organic hybrid porous material for alkene/alkane separations. By using self-assembly strategy and mild solvothermal synthesis, we will design and synthesize a series of novel anionic-framework porous materials. In order to achieve charge balance, a variety of metal ions will be immobilized into the pores of anionic-framework materials via ion-exchange method. The incorporated metal ions can form π-complexation with the carbon−carbon double bonds of alkene molecules to afford strong interactions between alkene molecules and the framework, thus enhancing the recognition and adsorption ability of these materials for alkene molecules. We will systematically investigate how the pore shapes, sizes and metal ions of these materials to affect the separation performance. On this basis, the selectivity and alkene adsorption capacity can be well modulated to achieve both high selectivity and high alkene adsorption amount in a single material. The adsorption sites of alkene molecules in the anionic-framework materials will be determined, and mechanistic analysis of the role of pore sizes and metal ions on improving alkene separation properties will also be elucidated.

烯烃（乙烯和丙烯）是化工生产中使用最多的化工原料，将它们和烷烃类副产品分离开是非常重要的分离过程。开发具有高选择性能的分离材料能有效解决传统的低温蒸馏分离技术存在的耗能高和成本高的缺陷，然而目前报道的分离材料的分离性能还不够理想，存在分离选择性和烯烃吸附能力难以兼具的缺陷。本项目以同时提高无机-有机杂化多孔材料的烯烃/烷烃分离选择性和吸附量为目标，设计和构筑一类具有有序规整孔结构的新型阴离子框架微孔材料；利用电荷平衡和离子交换法，引入金属阳离子客体到孔道内，通过与烯烃分子形成π-配位键来提高识别和吸附烯烃分子的能力；系统研究材料的微孔结构、大小和阳离子类型对乙烯/乙烷和丙烯/丙烷分离性能的影响；探寻最优的孔道大小和阳离子组合，在单一材料中实现对烯烃/烷烃分离的高分离选择性和高吸附能力的目标；阐明烯烃分子在这类阴离子框架材料中的吸附位点，揭示提高烯烃分离性能的作用机理。

烯烃（乙烯和丙烯）是化工生产中使用最多的化工原料，将它们和烷烃类副产品分离开是非常重要的分离过程。开发具有高选择性能的分离材料能有效解决传统的低温蒸馏分离技术存在的耗能高和成本高的缺陷，然而目前报道的分离材料的分离性能还不够理想，存在分离择性和烯烃吸附能力难以兼具的缺陷。本项目提出通过向有序多孔MOF材料中引入金属离子和精细调控孔道尺寸的策略，实现并优化乙烯/乙烷等混合气体的分离性能。设计合成了多种新型多孔MOF材料，通过向MOF材料的孔道内螯合Cu(I)金属阳离子，利用金属离子与乙烯分子间形成的π−络合作用，增强了材料对乙烯分子的作用力和识别能力，有效提高了乙烯/乙烷混合气体分离选择性，其选择性提高至80.8，高于目前报道的大部分分离材料。在此基础上，将该策略进一步推广至乙炔/二氧化碳分离，通过在阴离子框架MOF材料中引入Cu(I)−炔化学作用，将其选择性提高至目前最高的185。此外，开发并构筑了“类三明治型”双金属位点和乙炔密堆积等分离策略，大大提高了材料对乙炔的作用力和识别能力，为乙炔/二氧化碳分离材料的开发与研究提供了全新的视角和思路。开发了新型HOF材料并实现乙烯/乙烷反转吸附分离，通过精细设计和调控孔道结构，实现了高效的乙烯/乙烷反转吸附分离性能。这些研究成果为设计高性能分离材料提供了材料的新设计策略和原理，有利于提高材料对于烯烃和乙炔气体的分离选择性，进而克服了这些分离的trade-off效应，有望推动这项分离技术和高效分离材料的实际应用和发展。