Recent advances in polymer blend and metal-organic framework-based mixed matrix membranes for H2/CO2 separation

This review critically evaluates polymer-blend and metal-organic-framework (MOF)-based mixed-matrix membranes (MMMs) for H 2 /CO 2 separation, with emphasis on the relationship between membrane chemistry, polymer–filler interfaces, filler loading, operating conditions, transport mechanisms, and practically relevant separation performance. Unlike a purely descriptive survey, the review separates evidence obtained for H 2 /CO 2 from results for other gas pairs, compares H 2 permeability/permeance and H 2 /CO 2 selectivity where directly reported, and identifies when apparent gains are limited to ideal-gas testing or low-pressure conditions. The discussion covers conventional H 2 /CO 2 separation technologies, solution–diffusion and molecular-sieving mechanisms, PSF- and PEI-based membranes, composite and mixed-matrix architectures, Maxwell/Bruggeman/Lewis–Nielsen/Pal permeability models, and the role of CFD in membrane-module design. Particular attention is given to MOF family, interfacial compatibility, loading-dependent agglomeration, plasticization, mixed-gas competition, long-term stability, hollow-fiber scale-up, and techno-economic constraints. The resulting synthesis shows that high filler loading alone does not guarantee superior H 2 /CO 2 performance; interface control, thin selective layers, realistic mixed-gas testing, and stable operation at elevated temperature and pressure are more decisive for translation to pre-combustion hydrogen purification.