Investigation of metal ion additives on the suppression of ammonia loss and CO2 absorption kinetics of aqueous ammonia-based CO2 capture. (January 2017)

• Record Type: Journal Article
• Authors: Li, Lichun; Conway, William; Burns, Robert; Maeder, Marcel; Puxty, Graeme; Clifford, Sarah; Yu, Hai
• Is Part Of: International journal of greenhouse gas control. Volume 56(2017)
• Page Start: 165
• Page End: 172
• Publication Date: 2017-01
• Subjects: CO2 capture -- Ammonia loss -- Metal ion additives -- CO2 absorption rate -- Model calculations; Greenhouse gases -- Environmental aspects -- Periodicals; Air -- Purification -- Technological innovations -- Periodicals; Gaz à effet de serre -- Périodiques; Gaz à effet de serre -- Réduction -- Périodiques; Air -- Purification -- Technological innovations; Greenhouse gases -- Environmental aspects; Periodicals; 363.73874605
• DOI: 10.1016/j.ijggc.2016.11.016
• Languages: English
• ISSNs: 1750-5836

Abstract

Graphical abstract: Highlights: Metal ions M(II) = Zn(II), Cu(II) and Ni(II) were investigated as ammonia loss inhibitor. Directly reduction of ammonia concentration was introduced to suppress ammonia loss. Both methods suppress ammonia loss at a cost of CO2 absorption rate. Both methods decrease CO2 absorption capacity and increase solvent regeneration energy. Abstract: Aqueous ammonia is an attractive absorbent for the capture of CO2 from industrial flue gases. However evaporative ammonia loss limits the application of the ammonia-based CO2 capture process. The use of metal ion additives (where M(II) = Cu(II), Zn(II) and Ni(II)), has been reported previously for the effective suppression of ammonia loss in the post combustion capture of CO2 . In this study, we have investigated the absorption of CO2 into various M(II)/NH3 solutions, the resulting loss of ammonia to evaporation, and have attempted to rationalise the observed effects using an extended chemical model that includes all chemical reactions in solution. The theoretical and experimental investigations suggest that complexation of ammonia by metal ions effectively reduces the concentration of free ammonia, resulting in reduced evaporative loss but also reduced reactivity towards CO2 . Simple reduction of the total NH3 concentration to the same concentration of free NH3 concentration as that obtained by the addition of M(II) showed a similar reduction in the ammonia loss as well as the CO2 absorption rate. The effects on CO2 absorption capacity at 25 and 80 °C, cyclic capacity and regeneration energy are also simulated and discussed.