Improving regeneration properties of potassium-based alumina sorbents for carbon dioxide capture from flue gas

Gamma-alumina (gamma-Al2O3) is one of the most useful support or additive materials in the preparation of dry sorbent for CO2 capture from flue gas. However, when the gamma-Al2O3 was used in the preparation of dry sorbent, the potassium-based gamma-Al2O3 sorbent was deactivated by the forming of by-products like KAl(CO3)(OH)(2) during CO2 sorption. To overcome this problem, a new potassium-based sorbent using alpha-alumina (alpha-Al2O3) as a support was developed in this study. This sorbent showed excellent regeneration properties, as well as high CO2 capture capacity during multiple CO2 sorption and regeneration tests at 60 degrees C and 200 degrees C, respectively. These results were due to the formation of KHCO3, which could be easily regenerated even at 130 degrees C, during CO2 sorption without by-products like the KAl(CO3)(OH)(2) phase, resulting from the structure effect of alumina. From these results, it is concluded that alpha-Al2O3 can be used as a support or an additive material to design a regenerable potassium-based sorbent which shows excellent regeneration properties even at 130 degrees C. (C) 2012 Elsevier Ltd. All rights reserved.