Effect of NaNO_3 on MgO-CaCO_3 Absorbent for CO_2 Capture at Warm Temperature

摘要

The effect of NaNO_3 on the activation of MgCO_3-CaCO_3 double salts to form a MgO-CaCO_3 absorbent and the cyclic CO_2 absorption ability of the obtained absorbent have been investigated to analyze the affecting mechanism of NaNO,. The MgCO_3-CaCO_3 double salts were prepared by two methods: coprecipitation of Mg(NO_3)_2, Ca(NO_3)_2, and Na_2CO_3 and modification of dolomite by NaNO_3. The results indicate that NaNO, has an obvious effect on lowering the activation temperature of the MgCO_3-CaCO_3 double salts, and NaNO, is the key component in facilitating the CO_2 absorption by the MgO-CaCO_3 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 NaNO, facilitates the decomposition of MgCO_3 in MgCO_3-CaCO_3 double salts, affects the crystal lattice of the activated absorbents, and favors the CO_2 absorption by improving the ion diffusion in the absorbent.