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

Gamma-alumina (γ-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 γ-Al2O3 was used in the preparation of dry sorbent, the potassium-based γ-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 (α-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 °C and 200 °C, respectively. These results were due to the formation of KHCO3, which could be easily regenerated even at 130 °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 α-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 °C.