Abstract:

To obtain high-performance CO₂/N₂ separation membranes, a dual-functional filler prepared by mechanochemistry reaction of oxygen-etched molybdenum disulfide (a-MoS₂) and metal-organic framework material MIP-202 was used as the dispersed phase, and polyether block amide (Pebax-1657) was served as a continuous phase, and Pebax/a-MoS₂/MIP-202 mixed matrix membranes (MMMs) were prepared by solution casting. The chemical structure of filler was characterized by FT-IR. The chemical structure, microscopic structure, thermal stability and physical mechanical properties of MMMs were characterized by ATR-FTIR, SEM, TG and mechanical property testing. The effects of water content, dual-functional filler ratio, dual-functional filler content, feed pressure and operating temperature on the gas separation performance of the membranes were studied, and the long-time stability of MMMs under simulated flue gas (CO₂/N₂ volume ratio 15/85) conditions was investigated. The results showed that the best CO₂ permeability of MMMs was 380 Barrer with a CO₂/N₂ selectivity of 124.7 at 25℃ and 0.1 MPa, surpassing the upper bound proposed by McKeown et al in 2019, when the mass ratio of a-MoS₂ to MIP-202 was 5∶5 and the dual-functional filler content was 6%(mass). The separation performance of MMMs was not significantly degraded over 360 h testing, with an average CO₂ permeability of 358 Barrer and CO₂/N₂ selectivity of 120.1. This is mainly due to the synergistic improvement of the gas separation performance of the membrane by a-MoS₂ and MIP-202.

Key words: mixed matrix membranes, molybdenum disulfide, MIP-202, synergistic effect, CO₂ separation

摘要：

为了获得高性能的CO₂/N₂分离膜，把空气中氧刻蚀的二硫化钼（a-MoS₂）和金属有机框架材料MIP-202通过机械力化学反应制备的双功能填料作为分散相，聚醚嵌段酰胺（Pebax-1657）作为连续相，采用溶液浇铸法制备了Pebax/a-MoS₂/MIP-202混合基质膜。采用FT-IR表征了填料的化学结构，借助ATR-FTIR、SEM、TG和力学性能测试表征了混合基质膜的化学结构、微观形貌结构、热稳定性和物理力学性能。研究了水含量、双功能填料配比、含量、膜两侧压差和操作温度对膜气体分离性能的影响，并考察了模拟烟道气（CO₂/N₂体积比15/85）条件下混合基质膜的长时间运行稳定性。结果表明：在温度为25℃、膜两侧压差为0.1 MPa的操作条件下，a-MoS₂与MIP-202质量比为5∶5和双功能填料含量为6%（质量）时，膜的气体分离性能达到最优，CO₂渗透性和CO₂/N₂选择性分别为380 Barrer和124.7，超过了2019年McKeown等提出的上限值。连续测试360 h后，混合基质膜的性能没有明显降低，其平均CO₂渗透性和CO₂/N₂选择性分别为358 Barrer和120.1。这主要是由于a-MoS₂和MIP-202协同提高了膜的气体分离性能。

关键词: 混合基质膜, 二硫化钼, MIP-202, 协同效应, CO₂分离