金属有机骨架材料/聚酰亚胺混合基质膜的制备及气体分离性能

合成了3种不同结构、 粒径和气体吸附性能的金属有机骨架材料(MOFs): 微米级Cu₃(BTC)₂、 亚微米级ZIF-8和S-Cu₃(BTC)₂. 氮气吸附等温线分析结果表明, ZIF-8和Cu₃(BTC)₂具有较大比表面积(1653和1439 m²/g), S-Cu₃(BTC)₂的比表面积为171.4 m²/g. 用共混法将MOFs直接引入聚酰亚胺中制备了MOFs/聚酰亚胺混合基质膜(MMMs). X射线衍射(XRD)和全反射红外光谱(FTIR-ATR)分析结果表明, MOFs在混合基质膜中保持物理和化学稳定. 气体渗透测试结果表明, MOFs的加入使膜的气体渗透分离性能明显提高, S-Cu₃(BTC)₂使渗透系数增加了1.75倍; ZIF-8和Cu₃(BTC)₂使渗透系数增加了3倍左右; 同时, 膜的气体分离系数变化很小.

Preparation and Gas Separation Properties of Metal-organic Frameworks/Polyimide Mixed Matrix Membranes†

Three metal-organic frameworks(MOFs) with different structure, particle size and gas adsorption properties were synthesized: micron-scale Cu₃(BTC)₂, sub-micron ZIF-8 and S-Cu₃(BTC)₂. Nitrogen adsorption-desorption isotherms of MOFs showed that ZIF-8 and Cu₃(BTC)₂ possessed quite large BET surfaces(1653 and 1439 m²/g), and BET surface of S-Cu₃(BTC)₂ was 171.4 m²/g. MOFs were directly introduced into polyimide to fabricate mixed matrix membranes(MMMs). It was proved by XRD and FTIR-ATR characterizations that MOFs had no structural or chemical degradation in MMMs. Gas permeation test result indicated that gas separation properties of MMMs were enhanced as MOFs were added. Comparing with pure polyimide membrane, the adding of ZIF-8 or Cu₃(BTC)₂ brought gas permeability increase about 3 times, gas permeability of MMMs with S-Cu₃(BTC)₂ increased 175%. Meanwhile gas selectivies for O₂/N₂ and CO₂/CH₄ decreased slightly.