Development of poly(amidoamine) dendrimer/polyvinyl alcohol hybrid membranes for CO2 capture at elevated pressures

Abstract

A novel hybrid membrane of poly(amidoamine) (PAMAM) dendrimer/cross-linked poly(vinyl alcohol) (PVA) was developed for the selective separation of CO2 from a mixture of CO2 and H2. PAMAM dendrimers were incorporated into a cross-linked PVA matrix to improve CO2 separation performance at elevated pressures. An organic metal compound di-isopropoxy-bis(triethanol aminato) titanium (Ti cross-linker) was selected as the PVA cross-linker. The effects of cross-linker concentration and membrane thickness on separation performance were discussed. The optimum concentration of Ti cross-linker was from 10 to 25 wt%. CO2 permeance increased with decreasing thickness, but the CO2/H2 selectivity decreased with decreasing thickness. The effect of operating temperature on CO2 separation properties using of the thinnest membrane was discussed. Both QCO2 and CO2/H2 selectivity increased with increasing temperature. The CO2/H2 selectivity reached a maximum of 32 with CO2 permeance of 3.0 × 10-11 m3(STP)/(m2 s Pa) at 60°C under CO2 partial pressure of 560kPa. SEM observation and XPS spectra showed that the selective layer of thickness 6 μm of PAMAM/cross-linked PVA hybrid composite membrane onto a PVDF substrate was formed. The PAMAM dendrimer/cross-linked PVA membrane shows great potential for CO2separation from H2 in high pressure applications, such as IGCC process.