ZIF-93/Pebax 2533混合基质膜的制备及其CO_(2)/N_(2)分离性能研究

Preparation of ZIF-93/Pebax 2533mixed matrix membrane for CO_(2)/N_(2) separation

燃烧后CO_(2)捕获技术的发展对降低温室效应至关重要.CO_(2)选择性多孔骨架与高分子材料的结合有望开发高性能混合基质膜,用于CO_(2)/N_(2)混合气分离.考察了孔径在CO_(2)和N_(2)动力学直径之间的两种沸石咪唑酯骨架(ZIFs)材料,即ZIF-8和ZIF-93的吸附特性,结果表明ZIF-93由于骨架中醛基的存在具有CO_(2)优先吸附性能,其等摩尔CO_(2)/N_(2)混合气体的理论吸附选择性为25,远高于ZIF-8的6.5.通过旋涂法在PVDF载体上制备了具有非对称结构的ZIF-93/Pebax 2533混合基质膜.当ZIF-93负载量为12%时,ZIF-93/Pebax混合基质膜展示出最优的CO_(2)/N_(2)混合气分离性能,CO_(2)渗透率为47GPU,CO_(2)/N_(2)选择性为42.随着原料气中CO_(2)分压的增大,ZIF-93/Pebax混合基质膜的CO_(2)/N_(2)选择性基本不变,实现了高压下CO_(2)的高效分离.

The development of post-combustion CO_(2) capture technology is essential to reduce the greenhouse effect.The combination of CO_(2) selective porous framework and polymer materials is expected to develop high-performance mixed matrix membranes for mixed-gas CO_(2)/N_(2) separation.This work investigated the adsorption characteristics of two zeolitic imidazole frameworks(ZIFs)materials,namely ZIF-8 and ZIF-93 with pore diameters between the kinetic diameters of CO_(2) and N_(2) molecules.The results show that ZIF-93 has preferential adsorption of CO_(2) due to the presence of aldehyde groups in theframework.The theoretical adsorption selectivity of equimolar CO_(2)/N_(2) mixture is 25,which is much higher than that of ZIF-8(6.5).The ZIF-93/Pebax 2533 mixed matrix membrane was then prepared on the PVDF substrate by spin coating.When the ZIF-93 loading is 12%,the ZIF-93/Pebax mixed matrix membrane shows the best CO_(2)/N_(2) mixed gas separation performance,with CO_(2) permeance of 47 GPU and CO_(2)/N_(2) selectivity of 42.As the partial pressure of CO_(2) in the feed gas increases,the ZIF-93/Pebax mixed matrix membrane exhibits basically unchanged CO_(2)/N_(2) selectivity,realizing the efficient separation of CO_(2) under high pressure.