Absorption and reaction kinetics of amines and ammonia solutions with carbon dioxide in flue gas.

The removal system for the absorption of CO2 with amines and NH3 is an advanced air pollution control device to reduce greenhouse gas emissions. Absorption of CO2 by amines and NH3 solutions was performed in this study to derive the reaction kinetics. The absorption of CO2 as encountered in flue gases into aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), and NH3 was carried out using a stirred vessel with a plane gas-liquid interface at 50 degrees C. Various operating parameters were tested to determine the effect of these variables on the absorption kinetics of the reactants in both gas and liquid phases and the effect of competitions between various reactants on the mass-transfer rate. The observed absorption rate increases with increasing gas-liquid concentration, solvent concentration, temperature, and gas flow rate, but changes with the O2 concentration and pH value. The absorption efficiency of MEA is better than that of NH3 and DEA, but the absorption capacity of NH3 is the best. The active energies of the MEA and NH3 with CO2 are 33.19 and 40.09 kJ/mol, respectively.