State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, CAS, 457 Zhongshan Road, Dalian 116023 (China).
University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049 (China).
Angew Chem Int Ed Engl. 2015 Dec 14;54(51):15483-7. doi: 10.1002/anie.201505508. Epub 2015 Oct 30.
Fine-tuning of effective pore size of microporous materials is necessary to achieve precise molecular sieving properties. Herein, we demonstrate that room temperature ionic liquids can be used as cavity occupants for modification of the microenvironment of MOF nanocages. Targeting CO2 capture applications, we tailored the effective cage size of ZIF-8 to be between CO2 and N2 by confining an imidazolium-based ionic liquid [bmim][Tf2 N] into ZIF-8's SOD cages by in-situ ionothermal synthesis. Mixed matrix membranes derived from ionic liquid-modified ZIF-8 exhibited remarkable combinations of permeability and selectivity that transcend the upper bound of polymer membranes for CO2 /N2 and CO2 /CH4 separation. We observed an unusual response of the membranes to varying pressure, that is, an increase in the CO2 /CH4 separation factor with pressure, which is highly desirable for practical applications in natural gas upgrading.
微调微孔材料的有效孔径对于实现精确的分子筛性能是必要的。在此，我们证明室温离子液体可用作修饰 MOF 纳米笼微环境的空腔占据物。针对 CO2 捕集应用，我们通过原位离子热合成将基于咪唑的离子液体 [bmim][Tf2N] 限制在 ZIF-8 的 SOD 笼内，将 ZIF-8 的有效笼尺寸调至 CO2 和 N2 之间。由离子液体改性 ZIF-8 衍生的混合基质膜表现出渗透性和选择性的显著组合，超过了 CO2/N2 和 CO2/CH4 分离用聚合物膜的上限。我们观察到膜对变化压力的异常响应，即 CO2/CH4 分离因子随压力增加而增加，这对于天然气升级的实际应用非常理想。
