Adsorption of CO²-containing gas mixtures over amine-bearing pore-expanded MCM-41 silica: Application for gas purification

Adsorption of CO² on triamine-grafted pore-expanded mesoporous silica, TRI-PE-MCM-41, was investigated from very low pressure to 1 bar at four temperatures (298, 308, 318, 328 K) using gravimetric measurements. TRI-PE-MCM-41 exhibited one of the highest equilibrium capacities compared to other typical CO² adsorbents such as zeolites, activated carbons, and metal-organic frameworks (MOFs). In contrast, under the same pressure and temperature conditions, TRI-PE-MCM-41 exhibited very small uptakes of N ², CH⁴, H², and O² Column-breakthrough measurements of CO² in mixtures with other species showed exceedingly high selectivity of CO² over N ², CH⁴, H², and O² even at very low CO² concentrations, indicating that TRI-PE-MCM-41 issuitable adsorbent for gas purification applications. Moreover, water vapor was found to have a beneficial effect on CO² adsorption capacity even at very low CO² partial pressure, e.g. 400 ppm, without adverse effect on CO ² selectivity.