Study on CO2 capture in humid flue gas using amine-modified ZIF-8

• GCMC simulation and related experiment were utilized to calculate the co-adsorption of CO 2 and H 2 O on ZIF-8-PEI. • ZIF-8 with 30 wt.% PEI showed the highest CO 2 uptake of 1.4 mmol/g at dry condition. • The CO 2 adsorption capacity was improved to 1.7 mmol/g under 50% RH. • Water plays an excellent promoter role in CO 2 capture of ZIF-8-PEI30%. The CO 2 adsorption performance of most adsorbents were inhibited by water vapor which is a ubiquitous component of flue gas. It is critical to find an adsorbent with long-term stability in the presence of water vapor. In this study, both theoretical and experimental study were carried out to investigate the CO 2 capture capacity in humid flue gas of PEI impregnated ZIF-8. Grand canonical Monte Carlo (GCMC) simulation was performed to calculate the co-adsorption of CO 2 and H 2 O on ZIF-8-PEI. The simulation result indicates that water vapor has no negative impact on CO 2 adsorption of ZIF-8-PEI. Then, ZIF-8 with different PEI weight was synthesized and characterized. It is found that ZIF-8 with 30 wt.% PEI not only shows the highest CO 2 uptake of 1.4 mmol/g in dry condition but also exhibits excellent CO 2 /N 2 separation performance. More important is that the adsorption capacity of ZIF-8-PEI30% was improved to 1.7 mmol/g when the adsorbents were imposed to humid flue gas with 50% relative humidity (RH). Moreover, it only shows a slight decrease after 50 adsorption/desorption cycles. Hence, water plays an excellent promoter role in CO 2 capture of ZIF-8-PEI30%, and it is a promising adsorbent to be used in humid flue gas.