Recent developments in aqueous ammonia-based post-combustion CO2 capture technologies

Aqueous ammonia (NH₃) is a promising alternative solvent for the capture of industrial CO₂ emissions, given its high chemical stability and CO₂ removal capacity, and low material costs and regeneration energy. NH₃ also has potential for capturing multiple flue gas components, including NO_x, SO_x and CO₂, and producing value-added chemicals. However, its high volatility and low reactivity towards CO₂ limit its economic viability. Considerable efforts have been made to advance aqueous NH₃-based post-combustion capture technologies in the last few years: in particular, General Electric's chilled NH₃ process, CSIRO's mild-temperature aqueous NH₃ process and SRI International's mixed-salts (NH₃ and potassium carbonate) technology. Here, we review these research activities and other developments in the field, and outline future research needed to further improve aqueous NH₃-based CO₂ capture technologies.