Thin Film Composite Mixed-Matrix Membranes based on Matrimid and Zeolitic Imidazolate Frameworks for CO2/N2 separation performance

Membrane-based gas separation processes are a technology in continuous evolution. Various types of polymer membranes have been developed, many exhibiting high CO2 permeability and selective properties over competing gases such as N2 and CH4. In order to be competitive, membranes must be cheaper, more stable, more efficient and their production must be scalable. One solution is to develop thin film composites with mixed matrix membranes (TFC_MMM) that have the potential to boost productivity while maintaining low costs. In this work, TFC_MMMs containing Matrimid(r) mixed with 12%wt of ZIF-94 were prepared by kiss coating on a porous support. The SEM analysis showed that defect-free membranes with a 3 mm selective layer have been obtained. At 1 bar, the addition of ZIF resulted in the improved the separation performance for the CO2/N2 pair, with CO2 permeance of 4 GPU and CO2/N2 selectivity of 40, surpassing neat TFC-Matrimid (CO2 permeance~3 GPU, CO2/N2 selectivity~29). The use of ZIF-94 also had a stabilising effect on the membranes against CO2 plasticisation at high pressure.