Synthesis and characterization of crosslinked polyvinylalcohol/polyethyleneglycol blend membranes for CO2/CH4 separation

Both zeolite 5A filled and unfilled, crosslinked polyvinylalcohol (PVA)/polyethyleneglycol (PEG) blend membranes were synthesized and characterized for CO2/CH4 separation. The polar ether segments of PEG interact favorably with CO2, thus resulting in a high solubility selectivity, while PVA provides a mechanically strong polymer matrix. The crosslinking time, molecular weight of PEG and PEG (MW 200) content were found to significantly affect the gas transport property of resulting membranes, including gas permeability and CO2/CH4 selectivity. At 64 wt.% PEG (MW 200), the membranes showed good CO2 permeability of 80.2 Barrers (1 Barrer = 10−10 cm3 (STP) cm/cm2 s cmHg) and CO2/CH4 selectivity of 33 at 30 °C. Effects of the zeolite 5A loading, temperature and feed pressure were investigated for the gas separation performance of both zeolite-filled and unfilled PVA/PEG membranes. It was found that CO2/CH4 selectivity decreased as the zeolite 5A content increased, while CO2 permeability first decreased and then drastically increased. Increasing temperature enhanced CO2 permeability but sacrificed their selectivity for both zeolite-filled and unfilled PVA/PEG membranes. As temperature decreased, the unfilled PVA/PEG membranes could perform beyond the Robeson's upper bound. Compared to the unfilled PVA/PEG membrane, the zeolite-filled PVA/PEG membrane showed improved performance as feed pressure increased.