(688e) Amine-Functionalized Mesoporous Alumina for CO2 Capture From Flue Gas or Ambient Air: Preparation, Capture Capacity and Stability

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 [1]. 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 [2]. 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.

[1] W. Li, S. Choi, J. H. Drese, M. Hornbostel, G. Krishnan, P. M. Eisenberger, C. W. Jones, ChemSusChem 2010, 3, 899-903.

[2] W. Li, P. Bollini, S. A. Didas, S. Choi, J. H. Drese, C. W. Jones, ACS Appl. Mater. Interfaces 2010, 2, 3363-3372.