Abstract:

UTSA-280 is a typical molecular sieving metal-organic framework (MOF) for separating CO₂ from CH₄ or N₂, but the traditional solution-based synthesis method usually receives MOF particles with considerable size. Here an alternative mechanochemical way was used to fabricate small sized UTSA-280 particles, which was subsequently acted as filler materials in the polysulfone (PSf) based mixed matrix membranes (MMMs) for natural gas purification and CO₂ capture in flue gases. It shows that the introduction of UTSA-280 filler in the PSf matrix not only accelerates the transmission of CO₂ but also boosts the mixed gas separation factor of CO₂/CH₄ and CO₂/N₂. When the filler loading was 30%(mass) the CO₂/CH₄ and CO₂/N₂ separation factor were 56.39 and 53.17, respectively, and the CO₂ permeability was 18.61 Barrer, compared with pure membrane, the CO₂/CH₄ and CO₂/N₂ separation factor and CO₂ permeability showed 47.3%, 63.5% and 128.9% enhancement ratio, respectively, thus breaking the "trade-off" limitation. By introducing this specific MOF with molecular sieving character, the MOF based MMMs can improve the permeability of CO₂ as well as gas separation performance, which is of great significance to the purification of natural gas and the capture of CO₂ in flue gas.

Key words: metal-organic frameworks, molecular sieving, membrane, natural gas, CO₂ capture

摘要：

利用金属-有机骨架UTSA-280具有特定刚性尺寸的一维孔道可以筛分CO₂、CH₄、N₂的特性，采用机械化学研磨法减小其颗粒尺寸，将UTSA-280掺入聚砜（PSf）中制备MOF基混合基质膜，用于天然气提纯和烟道气CO₂捕获。结果表明，在PSf中掺入UTSA-280不仅可以增加聚合物的CO₂渗透通量而且提高了气体分离选择性。当UTSA-280掺杂量为30%（质量）时，混合基质膜对CO₂/CH₄、CO₂/N₂的分离因子分别为56.39和53.17，CO₂的渗透通量为18.61 Barrer，相对于PSf纯膜，选择性分别提高了47.3%和63.5%，CO₂渗透通量提高了128.9%，打破了“trade-off”效应。该工作通过引进具有分子筛分效应的MOF填料，能够增加气体通量的同时提高混合基质膜对含CO₂气体的分离性能，对天然气的提纯以及烟道气的CO₂的捕获有重要意义。

关键词: 金属-有机骨架, 分子筛分, 膜, 天然气, CO₂捕获