1. Introduction - Firenze University Press

CO2 capture capacity up to 150 th cycle. In order to confirm such an unexpected behavior another
experimental run has been accomplished confirming the previous observation (see black dots in Fig
8 (c)) with a good reproducibility. Finally for the double treated specimen no self reactivation
period was found at the beginning where a loss of activity was observed followed by a period of
good reversibility; beyond such a period a self reactivation was observed reaching a maximum at
~150 th cycle.
4. Conclusion
The multi-cycling CO2 sorption-desorption tests on synthetic CaO-Ca12Al14O33 sorbent show that
the reversibility of the CO2 uptake in repeated cycles is significantly improved compared that of
dolomite. Preliminary experiments aimed at increasing the capacity to retain carbon show that
exposing the material to carbon dioxide at 600 °C for 80 minutes prior the multi-cycling
experiments the sorbent activity is increased. Self reactivation period is found at the beginning of
the multi-cycling experiments or at later cycles reaching a maximum or a plateau in CO2 uptake.
Unexpected results are detected for the 75 % CaO sorbent which shows a continuously increase in
CO2 capture up to 150 th cycle under severe regeneration condition. The good reversibility showed
by this material in severe regeneration condition make it as a good candidate for CO2 acceptor in a
carbonate looping. In fact, in such a technology option a high concentrated CO2 stream is required
for final disposal [8]. In fact, carbon dioxide is collected at the outlet of the calciner where
regeneration of the sorbent happens. As a consequence the ideal CO2 acceptor should withstand
high CO2 concentration in the calciner to achieve a good regeneration extent to begin properly
another carbon capture cycle.
References
[1] Abanades J.C., Anthony E.J., Lu D.Y., Salvador C., Alvarez D., Capture of CO2 from
combustion gases in a Fluidized Bed of CaO. American Institute of Chemical Engineers Journal
2004, 50(7): 1614-1622.
[2] Grasa GS, Abanades JC.,CO2 capture capacity of CaO in long series of carbonation/calcination
cycles. Ind Eng Chem Res 2006; 45:8846-8851.
[3] Gallucci K., Stendardo S., Foscolo P.U., CO2 capture by means of dolomite in hydrogen
production from syn gas. Int J Hydrogen Energy 2008;33:3049-­‐3055.
[4] Delgado J., Aznar M.P., Corella J., Calcined dolomite, magnesite, and calcite for cleaning hot
gas from a fluidized bed biomass gasifier with steam: life and usefulness. Ind Eng Chem Res
1996;35:3637-­‐3643.
[5] Li Z., Cai N., Huang Y., Han H., Synthesis, Experimental Studies, and Analysis of a New
Calcium-Based Carbon Dioxide Absorbent. Energy Fuels 2005;19:1447-1452.
[6] Manovic V., Anthony E.J., Thermal Activation of CaO-Based Sorbent and Self-Reactivation
during CO2 Capture Looping Cycles. Environ. Sci. Technol. 2008;42:4170–4174.
[7] Chen Z., Song H.S., Portillo M., Lim C.J., Grace J.R., Anthony E.J., Long-Term
Calcination/Carbonation Cycling and Thermal Pretreatment for CO2 Capture by Limestone and
Dolomite. Energy & Fuels 2009;23:1437-1444.
[8] Calabro`A., Deiana P., Fiorini P., Girardi G., Stendardo S., Possible optimal configurations for
the ZECOMIX high efficiency zero emission hydrogen and power plant. Energy 2008;(33)
952–962.
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