Driven by the raising concentration of atmospheric CO2 and its implications for global climate change, technologies for carbon capture and sequestration (CCS) have extensively been developed during the past decade. In the post-combustion capture of CO2 from flue gas streams, absorption by amine-based aqueous solutions is a benchmark technology; however, this process suffers from energy-intensive regeneration requirements, oxidative degradation of the aqueous amines, as well as the corrosion of process equipment. As one of the emerging CCS technologies, adsorption of CO2 by several classes of solid adsorbents has been investigated. Specifically, solid-supported amines show great capture performance at low temperature.
Recently, we reported the first description of steam-stripping for the regeneration of supported amine adsorbents utilizing low-grade, low-cost steam that offers potential for “real” extraction of CO2 from other gases . For realizing such regeneration concept, the development of adsorbents possessing long-term stability under steam is a crucial step. Thus far, most of solid-supported amines have utilized silica as solid supports that could degrade upon exposure to steam . In this presentation, we describe syntheses of mesoporous alumina and amine-impregnated mesoporous alumina, and their performance in the capture of CO2 from simulated flue gas and simulated ambient air. In addition, the steam stability of alumina-supported adsorbents was evaluated and compared with that of silica-supported ones.
The mesoporous alumina synthesized by surfactant-mediated self-assembly of pseudobomite nanoparticles exhibited comparable surface area, large pore volume, and large and narrow mesopores that could accumulate polymeric amines up to 55% by weight. CO2 capture capacity using simulated flue gas and simulated ambient air obtained on the mesoporous alumina-supported amine adsorbents were slightly higher than those of SBA-15 mesoporous silica-supported materials. Additionally, temperature-programmed desorption of CO2 results suggested that CO2 binds to alumina-supported adsorbents somewhat stronger than the silica-supported ones. More importantly, the CO2 capture capacity on alumina-supported adsorbents was only slightly reduced after treatment under harsh steam conditions; while, CO2 capture capacity of silica-based adsorbents was drastically decreased. Overall, these results suggest that amine-functionalized mesoporous alumina is a promising material for CO2 adsorption-steam stripping processes.
 W. Li, S. Choi, J. H. Drese, M. Hornbostel, G. Krishnan, P. M. Eisenberger, C. W. Jones, ChemSusChem 2010, 3, 899-903.
 W. Li, P. Bollini, S. A. Didas, S. Choi, J. H. Drese, C. W. Jones, ACS Appl. Mater. Interfaces 2010, 2, 3363-3372.