Matrimid-Based Mixed Matrix Membranes: Interpretation and Correlation of Experimental Findings for Zeolitic Imidazolate Frameworks as Fillers in H2/CO2 Separation

In this paper we prepare three neat supported membranes, ZIF-8, ZIF-90, and Matrimid 5218, on porous alumina disks and compare their permeation behaviors in the separation of H-2/CO2 with the corresponding zeolitic imidazolate framework (ZIF)/Matrimid mixed matrix membranes (MMMs). These MMMs consist of ZIF-8 and ZIF-90 nanoparticles which are embedded in Matrimid. We found that the embedding of the nanoparticles modifies the separation performance of the Matrimid 5218 membrane for separating H-2 from CO2. TEM and SEM images of the ZIF-8 and ZIF-90/Matrimid MMMs show that the ZIFs are well embedded into the polymer. Thus, the separation behavior of these MMMs can be described with the Maxwell model. However, better separation results could be obtained by binding ZIF-90 particles covalently with ethylenediamine to the Matrimid matrix. In comparison to the MMMs that contain nonbound ZIFs, the covalent amine binding between the ZIF-90 particles and the Matrimid matrix leads to slightly lower permeabilities but a much higher H-2/CO2 separation factor.