CO2 capture using mesoporous alumina prepared by a sol-gel process

Mesoporous alumina (MA) having high surface area (812 m(2)/g) and large pore volume (0.83 cm(3)/g) with a narrow pore size distribution was prepared by a simple sol-gel process. The as-prepared MA was characterized by XRD, N-2 adsorption-desorption isotherms, and transmission electron microscopy (TEM). The CO2 adsorption performance of MA was tested under both low (<1 bar) pressure using a static volumetric system and high pressure (<30 bar) conditions using a gravimetric system. MA demonstrated a CO2 capture capacity of ca. 52 mg/g(adsorbent) at 1 bar, a value higher than that of a commercial alumina or 3-aminopropyltrimethoxysilane-grafted MCM-41. High pressure (0-30 bar) CO2 adsorption increased in a sequence of commercial alumina < SBA-15 < zeolite 13X < MA. Static adsorption and breakthrough experiments showed that MA offers high separation efficiency for CO2 against N-2. CO2 desorption at different temperatures was evaluated in order to identify regeneration conditions of MA after CO2 adsorption. PEI (polyethylenimine)-impregnated MA was also prepared and tested as a CO2 sorbent. The hybrid sorbent material achieved higher CO2 capture capacity (120 mg/g(sorbent)) than MA alone, with a level comparable to the sorption capacities of PEI functionalized mesoporous silica materials reported to date. Both as-prepared and PEI-impregnated MA exhibited stable adsorption-desorption behaviour during 5 consecutive test cycles. (C) 2010 Elsevier B.V. All rights reserved.