The effects of Cu(II) ion as an additive on NH3 loss and CO2 absorption in ammonia-based CO2 capture processes

Chemical CO2 absorption is one of the most cost- and energy-intensive processes in carbon capture and storage (CCS) technology. Among various absorption processes, ammonia-based processes attract much attention, due to many benefits: high CO2 absorption rate and low energy consumption for ammonia regeneration. Ammonia-based processes, however, have a problem to be solved for practical implementation due to the high vapor pressure of ammonia, which incurs ammonia loss during regeneration. In this study, the effect of Cu(II) ion as an additive on NH3 loss and CO2 absorption was investigated to examine the potential of Cu(II) ion to enhance the economic performance of ammonia-based processes. Continuous operations were conducted with and without the addition of Cu(II) ion. The results showed that the addition of Cu(II) ion noticeably decreased NH3 loss in the regeneration process due to the complexation of copper and ammonium ions, i.e., [Cu(NH3)4]2+. The Cu(II) addition also increased the CO2 absorption capacity in the absorption process because ammonia concentration remained higher. In conclusion, Cu(II) ion can be used to reduce ammonia make-up cost and to enhance CO2 absorption performance in ammonia-based CO2 capture processes.

► The effect of Cu(II) ion in ammonia-based CO2 capture processes is investigated.
► Cu(II) ion mitigates ammonia loss and increases CO2 absorption capacity.
► Cu(II) ion can reduce economic cost of the ammonia-based processes.