A kinetic and process modeling study of CO2 capture with MEA-promoted potassium carbonate solutions

Aqueous solutions of carbonate salts such as potassium carbonate (K2CO3) have gained widespread acceptance as viable solvents for pre and post combustion capture of carbon dioxide (CO2). However, due to poor reaction kinetics a rate promoter is considered essential to improve the rate of CO2 absorption and hydration to bicarbonate. Using a well characterized wetted-wall column, we have evaluated the reaction kinetics of CO2 absorption into a K2CO3 solution promoted with monoethanolamine (MEA) under conditions resembling those found at industrial CO2 capture plants. Results presented here show that at 63 °C the addition of MEA in small quantities, 1.1 M (5 wt.%) and 2.2 M (10 wt.%), accelerates the overall rate of absorption of CO2 in a 30 wt.% potassium carbonate solvent by a factor of 16 and 45 respectively. The Arrhenius expression for the reaction between CO2 and MEA is kMEA (M−1 s−1) = 4.24 × 109 exp(−3825/T [K]) where the activation energy is 31.8 kJ mol−1. Incorporating our experimental results into Aspen Plus™, we have developed an E-NRTL model that can replicate pilot plant and simulate industrial capture processes employing K2CO3 promoted with MEA as the capture agent.

► MEA significantly improves the overall absorption of CO2 into a K2CO3 solvent.
► Reaction kinetics of CO2 absorption into a MEA-promoted K2CO3 solution is reported.
► E-NRTL model suited for MEA-promoted K2CO3 system was developed using Aspen Plus™.
► MEA exhibits a larger rate constant at higher ionic strength conditions.