Gelation bath composition Permeance (GPUa) Selectivity CO2 CH4 H2 CO2/CH4 H2/CO2 0 vol.% DMAC, 100 vol. wt% deionized water 21.5 0.54 25 39.81 1.16 40 vol. % DMAC, 60 vol. % deionized water 10.25 0.36 12.1 28.47 1.18 80 vol.% DMAC, 20 vol. wt% deionized water 5.01 0.27 6.2 18.56 1.24 90 vol.% DMAC, 10 vol. wt% deionized water 2.90 0.23 3.7 12.61 1.28 Temperature: 25°C, feed pressure: 10 bar aGPU = 10−6 cm3 (STP) / (cm2 s cmHg)

Table 1: Gas permeance and CO2/CH4 and H2/CO2 selectivities of PDMS/PSf composite membranes (different gelation bath composition).