The increasing level of atmospheric CO2 has driven research efforts to the development of high-performance processes for CO2 capture from flue-gases in order to mitigate global warming effects mainly deriving from fossil fuels combustion. Post-combustion CO2 capture adopting ionic liquids (ILs) appears a promising route due to the tuneable chemico-physical properties and extremely low vapour pressure of ILs. A very challenging application of ILs is the inclusion in porous solids to increase their CO2 affinity and to overcome the limits of the industrial-scale application of ILs for CO2 capture, i.e. their high cost and viscosity. In this work CO2 removal performances of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4] and 1-ethyl-3-methylimidazolium glycine [Emim][Gly] ILs supported on Filtrasorb 400 and Nuchar RGC30 nanoporous activated carbons (ACs) are investigated. The sorbents preparation was performed by excess solution impregnation of each substrate with [Hmim][BF4] (two ethyl acetate solutions with IL concentrations C°=5.6×10-3 and 2.2×10-2 M) and [Emim][Gly] (one methanol solution C°=5.6×10-3 M) followed by solution filtration and residual solvent evaporation. Porosimetric characterization of functionalized ACs by means of N2 adsorption at 77 K revealed that investigated ILs preferentially adsorb in micropores. CO2 adsorption tests onto [Hmim][BF4] functionalized ACs were conducted in a fixed bed reactor at 303, 323 and 353 K and for simulated flue-gas streams (CO2 1-30% by vol., balance N2). Preliminary adsorption experiments for [Emim][Gly] functionalized carbons were performed under 15% CO2 streams at 303 and 353 K. Results highlighted that the use of [Hmim][BF4] for the functionalization of highly microporous ACs appears as not suitable for flue-gas treatment because pore blocking induced by this IL determines a worsening of the parent carbons CO2 adsorption capacity mostly at lower temperatures. On the contrary, the more-chemically CO2 affine amino acid-based [Emim][Gly] IL was effective in ameliorating the parent carbons sorptive performances towards CO2 at 353 K, hence confirming the interest of ACs functionalization by ILs in the field of CO2 capture.

CO2 adsorption from simulated flue-gas onto nanoporous activated carbons functionalized with ionic liquids

BALSAMO, MARCO;ERTO, ALESSANDRO;LANCIA, AMEDEO;MONTAGNARO, FABIO;
2014

Abstract

The increasing level of atmospheric CO2 has driven research efforts to the development of high-performance processes for CO2 capture from flue-gases in order to mitigate global warming effects mainly deriving from fossil fuels combustion. Post-combustion CO2 capture adopting ionic liquids (ILs) appears a promising route due to the tuneable chemico-physical properties and extremely low vapour pressure of ILs. A very challenging application of ILs is the inclusion in porous solids to increase their CO2 affinity and to overcome the limits of the industrial-scale application of ILs for CO2 capture, i.e. their high cost and viscosity. In this work CO2 removal performances of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4] and 1-ethyl-3-methylimidazolium glycine [Emim][Gly] ILs supported on Filtrasorb 400 and Nuchar RGC30 nanoporous activated carbons (ACs) are investigated. The sorbents preparation was performed by excess solution impregnation of each substrate with [Hmim][BF4] (two ethyl acetate solutions with IL concentrations C°=5.6×10-3 and 2.2×10-2 M) and [Emim][Gly] (one methanol solution C°=5.6×10-3 M) followed by solution filtration and residual solvent evaporation. Porosimetric characterization of functionalized ACs by means of N2 adsorption at 77 K revealed that investigated ILs preferentially adsorb in micropores. CO2 adsorption tests onto [Hmim][BF4] functionalized ACs were conducted in a fixed bed reactor at 303, 323 and 353 K and for simulated flue-gas streams (CO2 1-30% by vol., balance N2). Preliminary adsorption experiments for [Emim][Gly] functionalized carbons were performed under 15% CO2 streams at 303 and 353 K. Results highlighted that the use of [Hmim][BF4] for the functionalization of highly microporous ACs appears as not suitable for flue-gas treatment because pore blocking induced by this IL determines a worsening of the parent carbons CO2 adsorption capacity mostly at lower temperatures. On the contrary, the more-chemically CO2 affine amino acid-based [Emim][Gly] IL was effective in ameliorating the parent carbons sorptive performances towards CO2 at 353 K, hence confirming the interest of ACs functionalization by ILs in the field of CO2 capture.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/585642
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