Abstract:

Helium (He), owing to its unique physicochemical properties, plays an indispensable role in fields such as magnetic resonance imaging (MRI), semiconductor manufacturing and aerospace. Membrane separation technology has emerged as a research hotspot for helium purification due to its advantages of room-temperature operation without phase change. This review systematically summarized recent advances in high-performance polymeric membranes for helium separation from natural gas with a focus on the permeation mechanisms, structural designs and separation performances of cellulose acetate, polycarbonate, polyimide, polybenzimidazole and fluorinated polymer membranes for He/CH₄ and He/N₂ separation. By analyzing the effects of polymer chain architectures, free volume modulation and chemical modifications (e.g., fluorination, thermal rearrangement and incorporation of rigid groups) on separation performance, key strategies to enhance selectivity and permeability were elucidated. The study revealed that polyimide membranes incorporating intrinsic microporous structures surpassed the Robeson upper bound for He permeability. Fluorinated polymers demonstrated exceptional sieving capabilities attributed to their high free volume and chain-hindrance effects. Thermally rearranged membranes achieved a remarkable He/CH₄ selectivity (up to 324) by forming interconnected micropores through high-temperature structural reorganization. Furthermore, this review highlighted the role of asymmetric membrane fabrication techniques (e.g., interfacial polymerization and phase inversion) in reducing membrane thickness and enhancing flux. Challenges such as plasticization resistance, industrial processability and long-term stability were identified as critical areas for future research. This work provided theoretical insights and technical pathways for developing efficient and cost-effective helium-selective membranes, offering significant implications for addressing helium resource scarcity.

Key words: helium, polymeric membrane, polyimide membrane, helium/methane, polybenzimidazole membrane, permeation mechanism

摘要：

氦气（He）因为其独特的物理化学性质在核磁共振成像、半导体制备、航空航天等领域发挥着不可或缺的作用。膜分离技术凭借室温操作、无相变等优势，成为氦气提纯的研究热点。本文系统综述了高性能聚合物膜在天然气氦气分离领域的最新进展，重点探讨了醋酸纤维膜、聚碳酸酯膜、聚酰亚胺膜、聚苯并咪唑膜及氟化聚合物等材料的渗透机理、结构设计及其对He/CH₄和He/N₂的分离性能。通过分析聚合物链结构、自由体积调控及化学改性（如氟化、热重排、引入刚性官能团等）对分离性能的影响，揭示了提升选择性与渗透系数的关键策略。研究发现，聚酰亚胺膜通过引入固有微孔结构可使He渗透系数突破Robeson上限；氟化聚合物凭借大自由体积和链阻碍效应展现出卓越的筛分性能；热重排膜则通过高温重构形成互连微孔，显著提升了He/CH₄选择性（达324）。此外，本文总结了非对称膜制备工艺（如界面聚合、相转化法）对降低膜厚度与提高通量的作用，并指出耐塑化性、工业加工性及长期稳定性是未来研究的核心挑战。本文为开发高效、低成本的氦气分离膜材料提供了理论依据与技术方向，对缓解我国氦资源短缺问题具有重要意义。

关键词: 氦气, 聚合物膜, 聚酰亚胺膜, He/CH₄, 聚苯并咪唑膜, 渗透机理