CO 2 capture on polyethylenimine-impregnated hydrophobic mesoporous silica: Experimental and kinetic modeling

Abstract

CO 2 adsorption measurements for polyethylenimine (PEI)-impregnated pore-expanded MCM-41 were conducted by gravimetry to investigate the effects of (i) amine loading, (ii) CO 2 partial pressure, (iii) adsorption and desorption temperatures. Amine impregnation was conducted on ethanol-extracted pore-expanded MCM-41, referred to as PME which is a mesoporous silica whose internal surface is laden by a layer of cetyltrimethylammonium cations (CTMA). The well-dispersed PEI inside the PME hydrophobic channels exhibited a CO 2 adsorption capacity at 75 °C as high as 206 mg/g for 55 wt.% PEI loading. Moreover, the current PEI-impregnated PME materials had high CO 2 adsorption efficiency (g CO 2/g PEI) than any other PEI-containing adsorbent reported in the literature. In contrast to most PEI-impregnated materials reported in the literature, which because of diffusion resistance showed little or no CO 2 adsorption at room temperature, the PEI-impregnated PME material showed high potential for CO 2 removal at ambient temperature. Also a new adsorption kinetic model was proposed to describe the adsorption of CO 2 over amine-impregnated materials. The model was found to be in good agreement with experimental data under a wide range of conditions including different PEI loadings, CO 2 pressures and adsorption temperatures.