Molecularly Engineered 6FDA‐Based Polyimide Membranes for Sour Natural Gas Separation

Glassy polyimide membranes are attractive for industrial applications in sour natural gas purification. Unfortunately, the lack of fundamental understanding of relationships between polyimide chemical structures and their gas transport properties in the presence of H2S constrains the design and engineering of advanced membranes for such challenging applications. Herein, 6FDA‐based polyimide membranes with engineered structures were synthesized to tune their CO2/CH4 and H2S/CH4 separation performances and plasticization properties. Under ternary mixed sour gas feeds, controlling polymer chain packing and plasticization tendency of such polyimide membranes via tuning the chemical structures were found to offer better combined H2S and CO2 removal efficiency compared to conventional polymers. Fundamental insights into structure–property relationships of 6FDA‐based polyimide membranes observed in this study offer guidance for next generation membranes for sour natural gas separation. No need to be sour: CO2/CH4 and H2S/CH4 separation performance of glassy polyimide membranes can be tailored by finely tuning the DAM:DABA ratio in the 6FDA‐DAM:DABA polyimide backbone. This facile tunability is attractive for their applications for challenging sour gas separation (that is, methane contaminated with undesirable acid gases (CO2 and H2S)) across a spectrum of feed compositions.