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CO₂ Capture from Air Using Pelletized Polyethylenimine Impregnated MCF Silica

Wijesiri, Romesh P., Knowles, Gregory P., Yeasmin, Hasina, Hoadley, Andrew F. A., Chaffee, Alan L.
Industrial & engineering chemistry process design and development 2019 v.58 no.8 pp. 3293-3303
adsorption, air, carbon dioxide, foams, nitrogen, polyethyleneimine, process design, silica, sorbents, temperature, water content
Two polyethylenimine impregnated mesocellular foam silica sorbents (PEI_80a and PEI_80b) were evaluated for capturing CO₂ from 420 ppm of CO₂ in N₂ under both dry and humid conditions. A fixed bed adsorption setup was used to evaluate the CO₂ uptake under isothermal conditions between 33 and 81 °C with a gas flow of 200 mL/min. Under dry conditions, the highest capacity was observed at 46 and 52 °C for PEI_80a (1.29 mmol/g) and at 46 °C for PEI_80b (1.94 mmol/g). There was negligible uptake of CO₂ at 81 °C, indicating possible regeneration at relatively low temperatures. For PEI_80b, the introduction of moisture (0.5 and 2% mol-H₂O in feed gas) yielded up to 53% enhancement in capacity. Higher moisture levels (3% mol-H₂O) appeared to be detrimental to the CO₂ uptake. The highest capacity of 2.52 mmol/g was achieved at a temperature of 46 °C and a moisture level of 2% mol-H₂O.