Development of poly(amidoamine) dendrimer/polyvinyl alcohol hybrid membranes for CO_2 capture at elevated pressures

摘要

A novel hybrid membrane of poly(amidoamine) (PAMAM) dendrimer/cross-linked poly(vinyl alcohol) (PVA) was developed for the selective separation of CO_2 from a mixture of CO_2 and H2. PAMAM dendrimers were incorporated into a cross-linked PVA matrix to improve CO_2 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%. CO_2 permeance increased with decreasing thickness, but the CO_2/H_2 selectivity decreased with decreasing thickness. The effect of operating temperature on CO_2 separation properties using of the thinnest membrane was discussed. Both QCO_2 and CO_2/H_2 selectivity increased with increasing temperature. The CO_2/H_2 selectivity reached a maximum of 32 with CO_2 permeance of 3.0 × 10~(-11) m~3(STP)/(m~2 s Pa) at 60°C under CO_2 partial pressure of 560 kPa. SEM observation and XPS spectra showed that the selective layer of thickness 6 m 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 CO_2 separation from H_2 in high pressure applications, such as IGCC process.