2025/07/30 by Alexander Knebel, Ayisha Komal, Laura Calderón-Rodríguez +8 · 1 voice
Chemistry · Engineering · #Membrane Separation and Gas Transport #Metal-Organic Frameworks: Synthesis and Applications #Zeolite Catalysis and Synthesis
paper · pdf · doi:10.21203/rs.3.rs-7196877/v1
crossref issued 2025/07/30 · crossref published 2025/07/30 · openalex publication_date 2025/07/30 · crossref created 2025/07/30 · openalex created_date 2025/10/10 · crossref deposited 2026/04/17 · crossref indexed 2026/04/17 · openalex updated_date 2026/08/01
Abstract Helium is a finite but essential resource with important applications in medicine, research and aerospace. Conventional He-upgrading from natural methane gas (CH 4 ) is done by cryogenic distillation. This study presents energy efficient He-upgrading by membrane separation using the "dense" metal-organic framework (MOF) MIL-116(Ga), which enables high precision molecular sieving of non-adsorptive gases. MIL-116(Ga) membranes were synthesized on alumina after developing a method to homogeneously intergrow the MOF into a polycrystalline film. Single gas permeation experiments reveal exceptional ideal selectivity of α ideal (H 2 /CH 4 ) = 116 and α ideal (He/CH 4 ) = 78. In mixed gas permeation, the separation selectivity surpasses α ideal (He/CH 4 ) = 200 in a 1:1 mixture. Mixed-gas tests at realistic 4:96 He/CH 4 feed gas composition reached a selectivity of α(He/CH 4 ) = 31.2 and permeance for He of P(He) = 1800 GPU. Electron microscopy uncovered a complex, grain-boundary microstructure, which limits perfect molecular sieving but still enables superior separation performance. This work demonstrates that dense MOFs, at the example of MIL-116(Ga) enables high performance He-upgrading, setting a new benchmark amongst reported MOF-based membranes. The paper highlights the potential of dense MOFs for the separations of small, non-adsorptive gases and the need to address grain boundary diffusion in polycrystalline MOF membranes.