Cyclic olefin copolymer (COC)-metal organic framework (MOF) mixed matrix membranes (MMMs) for H2/CO2 separation

Abstract

In this study, thermoplastic based mixed matrix membranes (MMMs) were prepared by using cyclic olefin copolymer (COC) and two different metal organic frameworks (MOFs), HKUST-1 and MIL-53(Al) via solution mixing (SM) and melt processing (MP) methods. Structural and physical properties of COC, MOFs, and MMMs were characterized by SEM, XRD, TGA, and DMA methods. H2 and CO2 permeability values of MMMs were measured and ideal selectivity values (α) for H2/CO2 were determined. Characterization studies confirmed that the both preparation methods yielded a strong interfacial adhesion between MOF particles and COC. Different semi-empirical gas permeation models including the Maxwell, Maxwell‐Wagner‐Sillar, Bruggeman, Pal, Lewis‐Nielson, and Higuchi equations were used to fit relative increase in the gas permeation values of H2 as a function of volume fraction of HKUST-1. It was found that the Higuchi model was successfully fit the increase in H2 permeability. Loadings of 40 wt% of HKUST-1 and MIL-53 (Al) increased the H2 permeability by 85 % and 59 %, respectively and significantly improved the ideal selectivity (α) of H2/CO2, compared to COC. The gas separation performances of MMMs implied that the both series of COC/MOF membranes surpassed the Robeson's 2008 upper bound for H2/CO2 separation.