Covalent triazine framework CTF-fluorene as porous filler material in mixed matrix membranes for CO2/CH4 separation

The porous and highly stable filler material CTF-fluorene was incorporated with 8, 16 and 24 wt% into the polymer matrices polysulfone (PSF) and Matrimid (R). The resulting mixed matrix membranes (MMMs) were investigated by binary mixture CO2/CH4 mixed gas measurements. With increasing filler content in the MMMs, CO2 and CH4 permeabilities were enhanced with no loss of CO2/CH4 selectivity. All membrane systems were compared to theoretical permeability models and the best agreement could be found applying the Maxwell model. Further, calculations of the fractional free volume (FFV) confirm the contribution of filler porosity to improve the membrane permeability.