Effect of NaNO3 on MgO–CaCO3 Absorbent for CO2 Capture at Warm Temperature

Abstract

The effect of NaNO3 on the activation of MgCO3–CaCO3 double salts to form a MgO–CaCO3 absorbent and the cyclic CO2 absorption ability of the obtained absorbent have been investigated to analyze the affecting mechanism of NaNO3. The MgCO3–CaCO3 double salts were prepared by two methods: coprecipitation of Mg(NO3)2, Ca(NO3)2, and Na2CO3 and modification of dolomite by NaNO3. The results indicate that NaNO3 has an obvious effect on lowering the activation temperature of the MgCO3–CaCO3 double salts, and NaNO3 is the key component in facilitating the CO2 absorption by the MgO–CaCO3 absorbent. The affecting mechanism has also been analyzed using X-ray diffraction characterization, particle diameter distribution analysis, Brunauer–Emmett–Teller analysis, and the scanning electron microscopy characterization of the absorbents. The results indicate that the molten NaNO3 facilitates the decomposition of MgCO3 in MgCO3–CaCO3 double salts, affects the crystal lattice of the activated absorbents, and favors the CO2 a...