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

Abstract

A mesoporous silica supported polyamine-based protic ionic liquid (PIL) sorbent has been prepared by impregnating tetraethylenepentammonium nitrate [TEPA][NO3] onto the surface of SBA-15. This innovative hybrid adsorbent exhibits an excellent CO2 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 CO2 partial pressures. This adsorption performance can be ascribed to the synergistic effect of strong affinity between the PILs and CO2 and large surface area of the support which favors the diffusion of the PILs and CO2 molecules in its pores. In addition, density functional theory (DFT) calculations further reveal that CO2 preferentially reacts with the secondary amine –N(2)H in [TEPA][NO3] forming carbamate due to the high binding energy. The cyclic adsorption/regeneration experiment shows that nearly 90% of original CO2 adsorption capacity of the adsorbent is restored by N2 steam desorption at 373 K. Therefore this novel silica supported PIL system shows promise for CO2 removal and recovery applications.