CO2 capture with polyamine-based protic ionic liquid functionalized mesoporous silica

A mesoporous silica supported polyamine-based protic ionic liquid (PIL) sorbent has been prepared by impregnating tetraethylenepentammonium nitrate [TEPA][NO 3 ] onto the surface of SBA-15. This innovative hybrid adsorbent exhibits an excellent CO 2 adsorption rate in the rate-controlling step of 147 × 10 −3 mmol g −1 s −0.5 , at least threefold better than other IL-functionalized and amine-modified support systems. Moreover, the adsorption capacity is enhanced by up to 2.15 mmol/g for the adsorbent at 333 K and 0.15 bar, which represents excellent performance under low CO 2 partial pressures. This adsorption performance can be ascribed to the synergistic effect of strong affinity between the PILs and CO 2 and large surface area of the support which favors the diffusion of the PILs and CO 2 molecules in its pores. In addition, density functional theory (DFT) calculations further reveal that CO 2 preferentially reacts with the secondary amine –N(2)H in [TEPA][NO 3 ] forming carbamate due to the high binding energy. The cyclic adsorption/regeneration experiment shows that nearly 90% of original CO 2 adsorption capacity of the adsorbent is restored by N 2 steam desorption at 373 K. Therefore this novel silica supported PIL system shows promise for CO 2 removal and recovery applications.