High molecular fixed-site-carrier PVAm membrane for CO2 capture

Fixed-site-carrier (FSC) membranes for CO2 capture were prepared and investigated using commercial high molecular weight polyvinyl amine (PVAm) casted on two polysulfone (PSf) supports with different molecular weight cut-off (20,000 and 50,000). Using humidified premixed gas (10 mol% CO2, 90 mol% N2), a permeance of 0.28 m3 STP/m2 bar h and selectivity of 197 were obtained for a 1.2-mm membrane casted on 50,000 MWCO PSf at 2-bar feed pressure. For similar CO2/N2 selectivity values, the PVAm membrane presents a CO2 permeance at least one order of magnitude higher than other reported FSC membranes. The membranes showed stable performance during 45 days of intensive testing under the operating conditions.

The porosity (MWCO) of the support has an influence on both selectivity and permeance; hence the membrane may be tailored for the desired characteristics: high purity product or high flux. The high molecular weight PVAm ensures high densities of amino groups (the fixed site carrier) and consequently higher selectivity and permeance compared to low molecular weight PVAm. For similar CO2/N2 selectivity values, the PVAm membrane presents a CO2 permeance at least one order of magnitude higher than other reported FSC membranes. The membranes showed stable performance during 45 days of intensive testing: changing the relative humidity (RH%) of gas from 0% to 100%, the pressure from 1 bar to 15 bars, the temperature from 258C to 558C.