Gelation bath composition Permeance (GPU a) Selectivity H2 CH4 H2/CH4 0 vol.% DMAc, 100 vol. wt% deionized water 25.0 0.54 46.3 40 vol. % DMAc, 60 vol. % deionized water 12.1 0.36 33.6 80 vol.% DMAc, 20 vol. wt% deionized water 6.2 0.27 16.8 90 vol.% DMAc, 10 vol. wt% deionized water 3.7 0.23 16.1 Temperature: 25°C, feed pressure: 10 bar aGPU = 10−6 cm3 (STP) / (cm2 s cmHg)

Table 1: Gas permeance and H2/CH4 selectivity of PSf /PDMS composite membranes (different gelation bath composition).