Preparation and characterization of small molecular amine modified PVAm membranes for CO2/H2 separation

• Small molecular amines were firstly used to modify PVAm for CO2/H2 separation.
• Principles for selecting suitable small molecular amines were obtained.
• The PVAm–MEA/PS membrane shows high CO2/H2 performance and good stability.

Small molecular amines (SMAs) (ethanediamine (EDA), piperazine (PIP), monoethanolamine (MEA) and diethanol amine (DEA)) were separately used to modify the polyvinylamine (PVAm). ATR-FTIR, elemental analyzer, XRD and SEM were employed to characterize the SMA interacted PVAm. The PVAm–SMA/polysulfone (PS) membranes were developed by coating PVAm–SMA mixed solutions on the PS ultrafiltration membrane. CO2 permeance and CO2/H2 selectivity of the PVAm–SMA/PS membranes were investigated. Among different PVAm–SMA/PS membranes, the PVAm–MEA/PS membrane shows the highest CO2/H2 separation performance. Moreover, the effect of the selective layer thickness on the CO2/H2 separation performance of the PVAm–MEA/PS membrane was studied. With increasing the PVAm–MEA selective layer thickness, the CO2/H2 separation performance of the membrane apparently decreases. Finally, the CO2/H2 separation performance stability of the PVAm–MEA/PS membranes was investigated and no deterioration in the membrane permselectivity was observed.