Amine mixtures and the effect of additives on the CO2 capture rate

The mass transfer of CO2 into aqueous ammonia with a series of promoters was studied. Three promoters were chosen to represent three different chemical classes. These classes were alkanolamine, amino acid and inorganic base. Of these classes the alkanolamine showed the greatest enhancement of CO2 mass transfer, followed by the amino acid. The inorganic base did not show any enhancement. Two factors were identified that lead to the enhancement of CO2 mass transfer. The first factor was the alkanolamine and amino acid used have faster reactions with CO2 than ammonia. The second was the presence of ammonia in a high concentration provides additional sites for proton accepting; allowing more of the added alkanolamine or amino acid to react with CO2. This theory is supported by C13 NMR data. (C) 2010 Published by Elsevier Ltd.