基于功能化碳纳米管混合基质膜分离CO2的研究进展及产业化应用趋势

Recent Advances on Functionalized Carbon Nanotube Composite Membranes in CO2 Gas Separation

摘要:

二氧化碳（CO₂）的排放，是导致全球气候变暖的主要原因之一。CO₂的捕集、利用与封存技术（CCUS），被认为是减少温室气体的有效方式。膜分离技术作为一种高选择性和低能耗，以及具有较强的可扩展性的碳捕集方法，受到越来越多研究学者的青睐。综述了近年来功能化碳纳米管复合气体分离膜的主要研究进展，详细讨论了碳纳米管的特性、功能化改性、分散形态以及外场辅助对分离膜的影响机制，总结了不同功能化碳纳米管气体分离膜的特性。功能化复合分离膜是以高分子聚合物为基体，加入功能性填料形成的混合基质膜（MMMs），而碳纳米管（CNTs）相较于其他功能性填料，在分离膜的改性强化方面具有很大优势。研究结果表明：对CNTs进行功能基团接枝，有助于提高CO₂在MMMs中的扩散速度；CNTs的聚合物的改性，可加速CO₂在膜中的传输，提高MMMs对CO₂的选择性及渗透性；CNTs的均匀分散，可提高MMMs对CO₂的分离效率；外场（磁场和静电场）可使CNTs在聚合物基体中有序排列，为CO₂提供有序、长程、易传递的通道，进一步提高MMMs的渗透性。本研究总结了不同形态的CNTs对分离膜的影响，对碳纳米管复合气体分离膜，特别是碳纳米管混合基质膜的未来发展趋势提出了观点；并为以CO₂气体分离为重点的工业化应用指明了方向。

Abstract:

Carbon dioxide （CO₂） emissions are one of the main causes of global warming， and CO₂ capture， utilization and sequestration （CCUS） technology is considered to be an effective way to reduce greenhouse gases， in which the membrane separation technology， as a highly selective， low-energy， and highly scalable carbon capture method， has been favored by more and more researchers and scholars. This paper reviews the main progress of functionalized carbon nanotube composite gas separation membranes in recent years， discusses in detail the mechanism of carbon nanotube properties， functionalization modification and dispersion morphology on the separation membrane， and summarizes the properties of different functionalized carbon nanotube gas separation membranes. Functionalized composite separation membranes are mixed matrix membranes （MMMs） formed by adding functional fillers to a polymer matrix， while carbon nanotubes （CNTs） have done a better job of modifying and strengthening separation membranes. It was shown that grafting CNTs with functional groups helps to increase the diffusion rate of CO₂ in MMMs； modification of polymers with CNTs improves the selectivity and permeability of MMMs to CO₂； uniform dispersion of CNTs improves the separation efficiency of MMMs to CO₂； and the external field can lead to the orderly arrangement of CNTs in the polymer matrix， which provides orderly， long-range， and easy CO₂ transmission channels to further improve the permeability of MMMs. This paper points out the direction for the future research trend of carbon nanotube composite gas separation membranes and the industrialized application focusing on CO₂ gas separation.