CO2 capture in the form of thermally stable solid compounds using ammoniated brine

Capture of CO2 in the form of thermally stable solid compounds is an interesting alternative for CO2 sequestration and utilization. In this study, CO2 capture using ammonia base absorbent in a bubble column reactor with various parameters (NaCl concentration, reaction temperature, CO2 flow rate, and ammonia concentration) was investigated. The precipitated products mainly consisted of thermally unstable [ammonia salts; e.g. NH4HCO3, (NH4)2CO3] and stable solid [NaHCO3, Na2CO3] products. The results revealed that increasing NaCl concentration and/or ammonia concentration or decreasing reaction temperature and/or CO2 flow rate increased CO2 capture capacity and the amount of the stable solid products. Operating conditions set at 3.0 M of NaCl with 43 wt% of ammonia solution, a reaction temperature of 20 °C, and a CO2 flow rate of 100 mL/min were found to provide the maximum NaHCO3 and Na2CO3 amounts of 20.67 wt% and 39.41 wt%, respectively. The stable solid products were also characterized by SEM/EDS and XRD.