CO2 removal at temperatures of 300 to 600oC is desired because, the thermal efficiency is expected to be improved and it can be used to facilitate some equilibrium-restricted processes, such as steam reforming and water-gas-shift reaction processes. Removing CO2 under reaction conditions can shift the reaction equilibrium toward completion. Recently, we have reported that addition of molten salts, such as NaNO3, carbonate eutectic Li2CO3-Na2CO3-K2CO3 which become molten at the temperature of absorption and desorption, can facilitate the conversion of MgO to MgCO3. Similarly, it assists in the capture and release of CO2 by double salts such as MgO-Na2CO3 or MgO-CaCO3. These MgO based CO2 absorbents show very high and stable CO2 capacity at 300-400 oC. In this talk, we will report our recent progress on the development of CO2 absorbents to be used at higher temperatures. The sorbents are prepared using inexpensive dolomite by decomposing it into MgO-CaO, and small amounts of carbonate eutectic Li2CO3-Na2CO3-K2CO3 are added as a promoter. The sorbents are effective for CO2 capture over a temperature range of 400 to 700oC. Sorbents with CO2 capacity up to 6 mmol/g have been produced and they can be easily regenerated. Our results indicate that carbonate eutectic can not only improve the CO2 sorption but also desorption. The effect of molting point of carbonate eutectic will be discussed and the stability of sorbents will also be reported.

Carbonate eutectic promoted dolomite for CO2 removal

254th National Meeting (2017)

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