Highly efficient CH₄ purification by LaBTB PCP-based mixed matrix membranes

Membrane-based technology for CO₂/CH₄ separation has received significant interests due to its potentially lower energy consumption relative to that of conventional approaches such as cryogenic distillation and chemisorption. Engineering a new membrane material with excellent performance is a crucial step in achieving this goal. In this study, we report the facile fabrication of novel mixed-matrix membranes (MMMs) that contain a porous coordination polymer (PCP) filler (LaBTB). CO₂/CH₄ mixed-gas permeation measurements showed that LaBTB/6FDA-DAM polyimide exhibited reduced trade-off and plasticization effects and thus surpassed the 2008 Robeson upper-bound even under RH 70% moisture (stable CO₂ permeability of 700 barrer and CO₂/CH₄ selectivity of 30 within 120 h). Importantly, the positive effect of LaBTB within LaBTB/6FDA-DAM for selective CO₂ capture has been established by in situ IR spectroscopy. Excellent separation performance combined with their outstanding water/moisture stability suggests that LaBTB-based MMMs are promising candidates for feasible CO₂/CH₄ separation.