Keywords: adsorption, carbon dioxide, flue gas, MCM-41, mesoporous molecular sieve, polyethylenimine, separation
Adsorption separation of CO2 from simulated flue gas mixtures by novel CO2 "molecular basket" adsorbents
Adsorption separation of CO2 from simulated flue gas mixtures containing CO2, O2, and N2 by using a novel CO2 'molecular basket' adsorbent was investigated in a flow adsorption separation system. The novel CO2 'molecular basket' adsorbents were developed by synthesising mesoporous molecular sieve MCM-41 and modifying it with polyethylenimine (PEI). The influence of operation conditions, including feed flow rate, temperature, feed CO2 concentration, and sweep gas flow rate, on the CO2 adsorption/desorption separation performance and CO2 breakthrough were examined. The CO2 adsorption capacity was 91.0 ml (STP)/g-PEI, which was 27 times higher than that of the MCM-41 alone. Further, the adsorbent showed separation selectivity of greater than 1000 for CO2/N2 ratio and approximately 180 for CO2/O2, which are significantly higher than those of the MCM-41, zeolites, and activated carbons. Cyclic adsorption/desorption measurements showed that the CO2 'molecular basket' adsorbent was stable at 75°C. However, the CO2 'molecular basket' adsorbent was not stable when the operation temperature was higher than 100°C.