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.