Programmable Pore Environments in Multivariate ZIF Membranes for Ultra-Selective Helium Recovery from Natural Gas

High Resolution Image Download MS PowerPoint Slide Helium is an essential yet finite resource with critical applications in medical imaging and semiconductor manufacturing, whose production currently relies almost exclusively on energy-intensive cryogenic separation of trace helium from natural gas. Membrane-based separations offer an attractive alternative, but existing materials lack the selectivity required for industrial deployment. Here, we introduce a strategy for pore microenvironment programming in multivariate zeolitic imidazolate framework (MTV-ZIF) membranes, enabling ultraselective helium recovery under realistic feed gas conditions. By precisely combining Zn 2+, 2-methylimidazole, and halogen-substituted benzimidazole linkers, we create synergistic combinations of steric constraints and enhanced CH 4 –framework interactions, which collectively suppress CH 4 transport while preserving rapid He permeation. Under simulated industrial feed conditions (0.6% He/99.4% CH 4 by volume), the best-performing membrane delivered a record He/CH 4 selectivity of 3174, with stable operation over 960 h. Process simulations further show that a two-stage membrane cascade can deliver >99.95% He purity with an 83% reduction in energy demand compared to cryogenic distillation. These results highlight multivariate pore programming in MOFs as a powerful platform for efficient, low-energy He recovery from natural gas.