Anthropogenic emissions of carbon dioxide (CO2) have been identified as a major contributor to climate change. An attractive approach to tackle the increasing levels of CO2 in the atmosphere is direct extraction via absorption of CO2 from ambient air, to be subsequently desorbed and processed under controlled conditions. The feasibility of this approach depends on the sorbent material that should combine a long lifetime with nontoxicity, high selectivity for CO2, and favorable thermodynamic cycling properties. Adsorbents based on pore-expanded mesoporous silica grafted with amines have previously been found to combine high CO2 adsorption capacity at low partial pressures with operational stability under highly defined laboratory conditions. Here we examine the real potential and functionality of these materials by using more realistic conditions using both pure CO2, synthetic air, and, most importantly, ambient air. Through a combination of thermogravimetric analysis and Fourier transform infrared (TGA-FTIR) spectroscopy we address the primary functionality and by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy the observed degradation of the material on a molecular level. 1. Introduction Anthropogenic emissions of carbon dioxide (CO2) have attracted worldwide attention, since they are considered as the main contributor to climate change. Severe constraints on emission rates, however, could hinder economic growth, especially in developing countries [1, 2]. Even an issue of The Economist has been devoted to these issues: “Welcome to the Anthropocene” [3]. The number of different approaches suggested to tackle this problem is increasing rapidly [4]. Flue gases emitted from large point sources such as electricity generating power plants or cement factories are the focus of processes related to carbon capture and sequestration (CCS). CCS aims to capture the carbon dioxide directly at the emission sources and bury it in underground storages such as depleted oil and gas reservoirs. State-of the-art approaches for the capturing stage of CCS apply mainly amine-based aqueous solutions as monoethanolamine (MEA) or diethanolamine (DEA) [5, 6]. Such liquid amines, however, are subject to a number of serious drawbacks; most notably a part of these toxic compounds will be lost into the atmosphere by evaporation, and the remainder will gradually degrade by oxidative processes [5, 6]. Obviously, on-site capture of CO2 at large point sources can be conducted more cost-effectively than the capture from small and mobile sources like vehicles powered by
References
[1]
K. S. Lackner, P. Grimes, and H.-J. Ziock, “Capturing Carbon Dioxide From Air,” 2013, http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/7b1.pdf.
[2]
J. T. Houghton and Intergovernmental Panel on Climate Change Working Group III, Eds., Climate Change 1994, Cambridge University Press, Cambridge, UK, 1995.
[3]
The Economist, “Welcome to the Anthropocene, 26 May 2011,” 2013.
[4]
K. B. Lee, M. G. Beaver, H. S. Caram, and S. Sircar, “Reversible chemisorbents for carbon dioxide and their potential applications,” Industrial and Engineering Chemistry Research, vol. 47, no. 21, pp. 8048–8062, 2008.
[5]
D. M. D'Alessandro, B. Smit, and J. R. Long, “Carbon dioxide capture: prospects for new materials,” Angewandte Chemie, vol. 49, no. 35, pp. 6058–6082, 2010.
[6]
J. Oexmann, A. Kather, S. Linnenberg, and U. Liebenthal, “Post-combustion CO2 capture: chemical absorption processes in coal-fired steam power plants,” Greenhouse Gases, vol. 2, no. 2, pp. 80–98, 2012.
[7]
R. Socolow and M. Desmond, “Direct air capture of CO2 with chemicals, A Technology Assessment for the APS Panel on Public Affairs,” 2011, http://www.aps.org/policy/reports/assessments/upload/dac2011.pdf.
[8]
K. Z. House, A. C. Baclig, M. Ranjan, E. A. van Nierop, J. Wilcox, and H. J. Herzog, “Economic and energetic analysis of capturing CO2 from ambient air,” Proceedings of the National Academy of Sciences of the United States of America, vol. 108, no. 51, pp. 20428–20433, 2011.
[9]
S. Choi, J. H. Drese, P. M. Eisenberger, and C. W. Jones, “Application of amine-tethered solid sorbents for direct CO2 dapture from the ambient air,” Environmental Science & Technology, vol. 45, no. 6, pp. 2420–2427, 2011.
[10]
A. Sayari and Y. Belmabhout, “Stabilization of amine-containing CO2 adsorbents: dramatic effect of water vapor,” Journal of the American Chemical Society, vol. 132, no. 18, pp. 6312–6314, 2010.
[11]
Y. Belmabkhout and A. Sayari, “Effect of pore expansion and amine functionalization of mesoporous silica on CO2 adsorption over a wide range of conditions,” Adsorption, vol. 15, no. 3, pp. 318–328, 2009.
[12]
V. Nikulshina, N. Ayesa, M. E. Gálvez, and A. Steinfeld, “Feasibility of Na-based thermochemical cycles for the capture of CO2 from air-Thermodynamic and thermogravimetric analyses,” Chemical Engineering Journal, vol. 140, no. 1–3, pp. 62–70, 2008.
[13]
V. Nikulshina, C. Gebald, and A. Steinfeld, “CO2 capture from atmospheric air via consecutive CaO-carbonation and CaCO3-calcination cycles in a fluidized-bed solar reactor,” Chemical Engineering Journal, vol. 146, no. 2, pp. 244–248, 2009.
[14]
F. Brandani and D. M. Ruthven, “The effect of water on the adsorption of CO2 and C 3H8 on type X zeolites,” Industrial and Engineering Chemistry Research, vol. 43, no. 26, pp. 8339–8344, 2004.
[15]
R. Serna-Guerrero, Y. Belmabkhkout, and A. Sayari, “Influence of regeneration conditions on the cyclic performance of amine-grafted mesoporous silica for CO2 capture: an experimental and statistical study,” Chemical Engineering Science, vol. 65, no. 14, pp. 4166–4172, 2010.
[16]
J. C. Santos, F. D. Magalhaes, and A. Mendes, “Contamination of zeolites used in oxygen production by PSA: effects of water and carbon dioxide,” Industrial & Engineering Chemistry Research, vol. 47, no. 16, pp. 6197–6203, 2008.
[17]
T. C. Drage, A. Arenillas, K. M. Smith, and C. E. Snape, “Thermal stability of polyethylenimine based carbon dioxide adsorbents and its influence on selection of regeneration strategies,” Microporous and Mesoporous Materials, vol. 116, no. 1–3, pp. 504–512, 2008.
[18]
C. Chen, S.-T. Yang, W. S. Ahn, and R. Ryoo, “Amine-impregnated silica monolith with a hierarchical pore structure: enhancement of CO2 capture capacity,” Chemical Communications, no. 24, pp. 3627–3629, 2009.
[19]
R. S. Franchi, P. J. E. Harlick, and A. Sayari, “Applications of pore-expanded mesoporous silica. 2. Development of a high-capacity, water-tolerant adsorbent for CO2,” Industrial and Engineering Chemistry Research, vol. 44, no. 21, pp. 8007–8013, 2005.
[20]
S. Satyapal, T. Filburn, J. Trela, and J. Strange, “Performance and properties of a solid amine sorbent for carbon dioxide removal in space life support applications,” Energy and Fuels, vol. 15, no. 2, pp. 250–255, 2001.
[21]
H. Huang, R. Yang, D. Chinn, and C. L. Munson, “Amine-grafted MCM-48 and silica xerogel as superior sorbents for acidic gas removal from natural gas,” Industrial & Engineering Chemistry Research, vol. 42, no. 12, pp. 2427–2433, 2003.
[22]
X. Xu, C. Song, B. G. Miller, and A. W. Scaroni, “Adsorption separation of carbon dioxide from flue gas of natural gas-fired boiler by a novel nanoporous “molecular basket” adsorbent,” Fuel Processing Technology, vol. 86, no. 14-15, pp. 1457–1472, 2005.
[23]
R. Serna-Guerrero, E. Da'na, and A. Sayari, “New insights into the interactions of CO2 with amine-functionalized silica,” Industrial and Engineering Chemistry Research, vol. 47, no. 23, pp. 9406–9412, 2008.
[24]
R. Serna-Guerrero, Y. Belmabkhout, and A. Sayari, “Further investigations of CO2 capture using triamine-grafted pore-expanded mesoporous silica,” Chemical Engineering Journal, vol. 158, no. 3, pp. 513–519, 2010.
[25]
Y. Belmabkhout, R. Serna-Guerrero, and A. Sayari, “Amine-bearing mesoporous silica for CO2 removal from dry and humid air,” Chemical Engineering Science, vol. 65, no. 11, pp. 3695–3698, 2010.
[26]
P. J. E. Harlick and A. Sayari, “Applications of pore-expanded mesoporous silicas. 3. Triamine silane grafting for enhanced CO2 adsorption,” Industrial & Engineering Chemistry Research, vol. 45, no. 9, pp. 3248–3255, 2006.
[27]
R. Serna-Guerrero, Y. Belmabkhout, and A. Sayari, “Triamine-grafted pore-expanded mesoporous silica for CO2 capture: effect of moisture and adsorbent regeneration strategies,” Adsorption, vol. 16, no. 6, pp. 567–575, 2010.
[28]
P. J. E. Harlick and A. Sayari, “Applications of pore-expanded mesoporous silica. 5. Triamine grafted material with exceptional CO2 dynamic and equilibrium adsorption performance,” Industrial & Engineering Chemistry Research, vol. 46, no. 2, pp. 446–458, 2007.
[29]
N. R. Stuckert and R. T. Yang, “CO2 capture from the atmosphere and simultaneous concentration using zeolites and amine-grafted SBA-15,” Environmental Science & Technology, vol. 45, no. 23, pp. 10257–12264, 2011.
[30]
C. W. Jones, “CO2 capture from dilute gases as a component of modern global carbon management,” Annual Review of Chemical and Biomolecular Engineering, vol. 2, pp. 31–52, 2011.
[31]
Y. Belmabkhout, R. Serna-Guerrero, and A. Sayari, “Adsorption of CO2-containing gas mixtures over amine-bearing pore-expanded MCM-41 silica: application for gas purification,” Industrial and Engineering Chemistry Research, vol. 49, no. 1, pp. 359–365, 2010.
[32]
R. Steeneveldt, B. Berger, and T. A. Torp, “CO2 capture and storage: closing the knowing-doing gap,” Chemical Engineering Research and Design, vol. 84, no. 9, pp. 739–763, 2006.
[33]
R. O. Idem and A. Bello, “Pathways for the formation of products of the oxidative degradation of CO2-loaded concentrated aqueous monoethanolamine solutions during CO2 absorption from flue gases,” Industrial & Engineering Chemistry Research, vol. 44, no. 4, pp. 945–969, 2005.
[34]
Y. Belmabkhout and A. Sayari, “Isothermal versus non-isothermal adsorption-desorption cycling of triamine-grafted pore-expanded MCM-41 mesoporous silica for CO2 capture from flue gas,” Energy and Fuels, vol. 24, no. 9, pp. 5273–5280, 2010.
[35]
A. Sayari, A. Heydari-Gorji, and Y. Yang, “CO2-induced degradation of amine-containing adsorbents: reaction products and pathways,” Journal of the American Chemical Society, vol. 134, no. 33, pp. 13834–13842, 2012.
[36]
P. C. Rooney, T. R. Bacon, and M. S. DuPart, Hydrocarbon Processing, Ibid Press, Chicago, Ill, USA, 1996.
[37]
Annual report on air pollution in 2010, G？teborg, Sweden, R, 2011:10.
