CO₂ capture from the atmosphere using nanoporous-material-supported polyethylenimine sorbents

CO₂ capture from the atmosphere (air capture) may play an important role in reduction of CO₂ concentration in the atmosphere and offer a route to make carbon-neutral liquid hydrocarbon fuels for vehicles and aircrafts by converting CO₂ to the synthetic fuels. In the present study, CO₂ capture from the atmosphere using developed polyethylenimine (PEI) sorbents supported on nano pore-materials, including SBA-15 and silica gel, with 50 wt % PEI loading (PEI50/SBA-15 and PEI50/SG) was explored. Effects of the sorption temperature and sorption space velocity as well as regenerability of the sorbents were examined. It was found that both PEI50/SBA-15 and PEI50/SG sorbents were able to capture CO₂ from the real air with the CO₂ concentration of 400 ppmv. Interestingly, both sorbents showed a higher sorption capacity at the room temperature (25 °C, 83-85 mg-CO₂/g-sorbent) than that at higher temperature (75 °C, 32-34 mg-CO₂/g-sorbent) for CO₂ capture from the real air, which is different from the CO₂ capture from the flue gas with CO₂ concentration around 14 v % reported in our previous study. The gas hourly space velocity (GHSV) in sorption had almost no effect on the sorption capacity when the GHSV increased from 1880 to 7500 h^-1. The saturated at 90 °C without loss in the capacity. The results indicate that PEI50/SBA-15 and PEI50/SG is promising sorbents for CO₂ capture from the atmosphere.