https://doi.org/10.1016/j.ijggc.2016.11.016
In the above paper, the CO2 absorption capacity using ammonia with and without the addition of metal ions was investigated. Although the addition of metal ions could reduce ammonia loss. The results (Figure 5) showed that the addition of metal ions could decrease the ammonia concentration and resulted in the reduction of cyclic capacity and in particular, the solvent regeneration energy was enhanced with the addition of metal ions. Furthermore, at 25 °C, Zn(II)-NH3 solution showed the lowest value which was due to the formation of ZnCO3. The increase of absorption temperature to 80 °C largely reduced the CO2 absorption capacity from around 1.5 M to 0.7 M.