Novel tertiary amino containing thin film composite membranes prepared by interfacial polymerization for CO2 capture

A novel tertiary amine group containing fixed carrier thin film composite (TFC) membrane was developed by the interfacial polymerization of 3,3′-Diamino-N-methyldipropylamine (DNMDAm) and trimesoyl chloride (TMC) on the polysulfone (PS) support membrane. ATR-FTIR, XPS, AFM and SEM were employed to characterize the active surface of the composite membrane. The gas transport property of the DNMDAm-TMC/PS membrane was investigated by studying the permselectivity varying with feed gas pressure and the possible reactions between gases and the membrane. Furthermore, the effects of two important factors (the DNMDAm concentration and the TMC concentration) on membrane morphology and performance were investigated. It was found that both the DNMDAm concentration and the TMC concentration play important roles in determining the membrane morphology and performance, which may reconcile some contradictory findings in some references. Moreover, the DNMDAm-TMC/PS composite membrane showed both good CO2/N2 and CO2/CH4 separation performance. For CO2/N2 gas mixture (20/80 by volume), the membrane prepared with 0.0062 mol/l of DNMDAm and 0.0226 mol/l of TMC displayed a CO2 permeance of 173 GPU and CO2/N2 selectivity of 70 at 0.11 MPa feed pressure. For CO2/CH4 gas mixture (10/90 by volume), the same membrane showed a CO2 permeance of 118 GPU and CO2/CH4 selectivity of 37 at 0.11 MPa feed pressure. The high CO2/N2 and CO2/CH4 separation performance of DNMDAm-TMC/PS composite membrane was mainly attributed to the thin film thickness and the properties of tertiary amino groups.