Comprehensive study of the kinetics of the oxidative degradation of CO2 loaded and concentrated aqueous monoethanolamine (MEA) with and without sodium metavanadate during CO2 absorption from flue gases

A comprehensive mechanistic-based kinetic study of the oxidative degradation of CO2 loaded MEA, with and without a corrosion inhibitor (NaVO3). was performed in a stainless steel rotary-type autoclave with MEA concentrations of 11.4 and 17.9 mol %, NaVO3 concentration of 0.1 mol %, 02 pressures of 250 and 350 kPa, and CO2 loading ranging from 0 to 0.44 (mol of CO2)/(mol of MEA) at temperatures of 328-393 K (typical absorber and stripper temperatures). The results showed that the presence of NaVO3 and increases in MEA concentration, temperature, or O-2 pressure resulted in an increase in the MEA degradation rate. In contrast, an increase in CO2 loading led to a decrease in the degradation rate. The general mechanistic rate model obtained to represent all the systems investigated was of the following form: - r(MEA) {k(1)(1)[MEA](a)[O-2](b)}/{k(2) + k(3)[O-2](c) + k(5)[CO2](e)}. This rate model shows that in a CO2 loaded system, the loaded CO2 acts as a degradation inhibitor. In addition, the order of reaction with respect to MEA (a) for all the systems investigated was similar to 1.