Adsorption separation of carbon dioxide from flue gas of natural gas-fired boiler by a novel nanoporous “molecular basket” adsorbent

A novel nanoporous CO2 “molecular basket” adsorbent has been developed and applied in the separation of CO2 from the flue gas of a natural gas fired boiler. The nanoporous CO2 “molecular basket” adsorbent was prepared by uniformly dispersing polyethylenimine (PEI) into the pores of mesoporous molecular sieve MCM-41. The use of MCM-41 and PEI had a synergetic effect on the CO2 adsorption. The rates of CO2 adsorption/desorption of PEI were also greatly improved. Adsorption separation results showed that CO2 was selectively separated from simulated flue gas and flue gas of a natural gas-fired boiler by using this novel adsorbent. The adsorbent adsorbed very little N2, O2 and CO in the flue gas. Moisture had a promoting effect on the adsorption separation of CO2 from flue gas. The adsorbent simultaneously adsorbed CO2 and NOx from flue gas. The adsorbed amount of CO2 was around 3000 times larger than that of NOx. The adsorbent was stable in several cyclic adsorption/desorption operations. However, very little NOx desorbed after adsorption indicating the need for pre-removal of NOx from flue gas before capture of CO2 by this novel adsorbent.