Comparison of absorption rates and absorption capacity of ammonia solvents with MEA and MDEA aqueous blends for CO2 capture

In this work we present the experimental results of absorption rates and absorption capacity for the CO2 absorption by ammonia (NH3) aqueous solutions. Experiments are carried out in a thermoregulated Lewis-type cell reactor and are achieved in temperature and concentration ranges of 278–303 K and 2–5wt.% NH3 respectively. The obtained values for absorption kinetic rates and absorption capacity are compared with those available for alkanolamine solvents, commonly used to absorb CO2. In order to achieve this comparison, data available in studies about alkanolamine solvents at 303–333 K and 5–50wt.% for alkanolamines solutions were considered. Results show that CO2 absorption by NH3 is faster than the one carried out by MDEA, except for 2wt.% NH3 at 288 K. At 278 K and using aqueous solutions of 3wt.% NH3, the absorption rate is almost identical to the one reached with MDEA solvent. The highest absorption capacity, also compared with alkanolamine solution, is reached with aqueous solutions of 5wt.% NH3 at 278 K and 303 K.