CO₂ capture on polyethylenimine-impregnated hydrophobic mesoporous silica: Experimental and kinetic modeling

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2011-09, Vol.173 (1), p.72-79
• Main Authors: Heydari-Gorji, Aliakbar, Sayari, Abdelhamid
• Format: Article
• Language: English
• Subjects: adsorbents; Adsorption; ambient temperature; Applied sciences; cations; Chemical engineering; desorption; Exact sciences and technology; gravimetry; hydrophobicity; silica
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2011.07.038

CO₂ adsorption measurements for polyethylenimine (PEI)-impregnated pore-expanded MCM-41 were conducted by gravimetry to investigate the effects of (i) amine loading, (ii) CO₂ 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 CO₂ adsorption capacity at 75°C as high as 206mg/g for 55wt.% PEI loading. Moreover, the current PEI-impregnated PME materials had high CO₂ adsorption efficiency (g CO₂/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 CO₂ adsorption at room temperature, the PEI-impregnated PME material showed high potential for CO₂ removal at ambient temperature. Also a new adsorption kinetic model was proposed to describe the adsorption of CO₂ 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, CO₂ pressures and adsorption temperatures.