Thermal degradation of crosslinked copolyimide membranes to obtain productive gas separation membranes

The pyrolysed membrane obtained from the precursor with the lowest content of anhydride groups showed the highest permeability values: 101, 25, 17 and 446 barrers to O2, N2, CH4 and CO2 respectively, and a selectivity to CO2/CH4 of 26, good enough to place this membrane close to Robeson's new upper bound (2008), while the crosslinked precursor membrane fell below Robeson's old upper bound (1991).