Amine modified mesocellular siliceous foam (MCF) as a sorbent for CO2

Abstract

Adsorption is considered a promising method for carbon capture. CO2 adsorbents take a variety of forms – but one approach is to fill mesoporous substrates with a polymeric CO2 selective sorbent. SBA-15 and mesocellular siliceous foam (MCF) are high pore volume, high surface area ordered mesoporous materials for which modification with amine should result in high capacity, highly selective adsorbents. SBA-15 and MCF were separately loaded with approximately one pore volume equivalent of linear polyethyleneimine (PEI) (Mw = 2500) or branched PEI (Mn = 1200). CO2 adsorption/desorption isotherms under dry CO2 were obtained at 75, 105 and 115 ◦C. The CO2 adsorption/desorption kinetics were improved with temperature, though the CO2 capacities generally decreased. The adsorption capacity for MCF loaded with branched PEI at 105 and 115 ◦C were 151 and 133mg/g adsorbent, respectively (in 50% CO2/Ar, 20 min adsorption time). These are significantly higher than the adsorption capacity observed for SBA-15 loaded with branched PEI under same conditions, which were 107 and 83mg/g adsorbent, respectively. Thus the results indicate that, on a unit mass basis, amine modified MCF’s are potentially better adsorbents than amine modified SBA-15 for CO2 capture at modestly elevated temperature in a vacuum swing adsorption process.