ab initio Thermodynamic Study of the CO2 Capture Properties of M2CO3 (M = Na, K)- and CaCO3-Promoted MgO Sorbents Towards Forming Double Salts

Received: May 30, 2013
Revised: July 11, 2013
Accepted: July 11, 2013
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2013.05.0178  

Cite this article:
Duan, Y., Zhang, K., Li, X.S., King, D.L., Li, B., Zhao, L. and Xiao, Y. (2014). ab initio Thermodynamic Study of the CO2 Capture Properties of M2CO3 (M = Na, K)- and CaCO3-Promoted MgO Sorbents Towards Forming Double Salts. Aerosol Air Qual. Res. 14: 470-479. https://doi.org/10.4209/aaqr.2013.05.0178

ABSTRACT

The CO₂ capture properties of M₂CO₃ (M = Na, K)-promoted and CaCO₃-promoted MgO sorbents are investigated by first-principles density functional theory complemented with lattice phonon calculations. The calculated thermodynamic properties indicate that by forming double salts (M₂Mg(CO₃)₂ and CaMg(CO₃)₂), compared to pure MgO, the maximum allowable CO₂ capture temperatures of the M₂CO₃- and CaCO₃- modified MgO sorbents are shifted to higher temperature ranges. Under pre-combustion conditions with P_CO2 = 10 bar, the Na₂CO₃-promoted and CaCO₃-promoted MgO sorbents can capture CO₂ at temperatures as high as 915 K and 740 K respectively. While under post-combustion conditions with P_CO2 = 0.1 bar, their maximum allowable CO₂ capture temperatures are 710 K and 600 K respectively. However, when adding K₂CO₃ into MgO, under both pre- and post-combustion conditions, its maximum CO₂ capture temperatures only increased about 10 K relative to pure MgO. These results indicate that by mixing another solid into MgO, it is possible to shift its CO₂ capture temperature to fit practical industrial needs.

Keywords: CO2 capture sorbents; Double salt sorbents; Density functional theory; Lattice phonon dynamics; Thermodynamics