Polyimide mixed matrix membranes: preparation and characterization for CO2 selective separation

CO2 removal and / or capturing is one of the most important tasks in gas separation and environmental protection. Some mixed matrix membranes (MMMs) were fabricated in order to improve membrane separation performance of CO2 selective permeation using polyimide of Matrimid 5218 as backbone and zeolite 4A as filler. Scanning Electron Microscopy (SEM) analysis showed acceptable connections between the two phases and the MMMs performed higher performances for CO2 permeation compared with the neat polymeric membrane to some extent. Although a glassy polyimide was used, thermal treatment at a temperature around glass transition temperature (Tg) of the polyimide repaired probable defects and there were no voids around the fillers, as gas permeation tests revealed. Also, MMMs showed higher thermal stabilities than that of neat polymeric membrane. This is essential for many CO2 separation and capturing operations.