Kinetics of the Absorption of CO2 into Mixed Aqueous Loaded Solutions of Monoethanolamine and Methyldiethanolamine

• Published in: Industrial & engineering chemistry research 2006-04, Vol.45 (8), p.2608-2616
• Main Authors: Ramachandran, Naveen, Aboudheir, Ahmed, Idem, Raphael, Tontiwachwuthikul, Paitoon
• Format: Article
• Language: English
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie0505716

The kinetics of absorption of CO2 in loaded mixed methyldiethanolamine (MDEA) and monoethanolamine (MEA) solutions was investigated in a laboratory laminar jet apparatus. The experiments were conducted over the temperature range of 298−333 K, MDEA/MEA wt ratio of 27/03, 25/05 and 23/07, total amine concentration of 30 wt %, and CO2 loading from 0.005 to 0.15 (mol of CO2)/(mol of total amine). Physical properties such as density, viscosity, diffusivity, and solubility of the system were calculated from published data and/or models. Reaction mechanisms, namely, zwitterion and termolecular, were used to interpret the kinetic data. It was observed that the zwitterion mechanism in its original form could not predict the individual kinetic rate constants. Equally, the termolecular mechanism with water in the apparent reaction rate term also did not yield any reasonable results. A modified termolecular mechanism, which included the contribution of hydroxide ions, was able to predict the kinetics of a CO2 loaded mixed alkanolamine solution satisfactorily with MDEA not participating with MEA in the kinetics. Individual reaction rate constants were predicted based on the modified termolecular mechanism.