Ab Initio Thermodynamic Study of the CO2 Capture Properties of Potassium Carbonate Sesquihydrate, K2CO3•1.5H2O

By combining density functional theory and lattice phonon dynamics, the thermodynamic properties of CO2 absorption/desorption reactions with dehydrated potassium carbonates through K2CO3 center dot 1.5H(2)O + CO2 = 2KHCO(3) + 0.5H(2)O(g) are analyzed. The energy change and the chemical potential of this reaction have been calculated and used to evaluate its thermodynamic properties and phase transitions. The results indicate that the K2CO3 center dot 1.5H(2)O can only be applied for postcombustion CO2 capture technology at temperatures lower than its phase transition temperature, which depends on the CO2 pressure and the steam pressure with the best range being P-H2O <= 1.0 bar. Above the phase transition temperature, the sorbent will be regenerated into anhydrous K2CO3. If the steam pressure P-H2O is much greater than 1.0 bar, it is possible to use the K2CO3 center dot 1.5H(2)O sorbent for precombustion CO2 capture technology. Compared to anhydrous K2CO3, K2CO3 center dot 1.5H(2)O requires less energy for regeneration.