SO2 effect on monoethanolamine oxidative degradation in CO2 capture process

This work aimed at studying the SO2 effect on monoethanolamine oxidative degradation during CO2 capture process. Aqueous monoethanolamine (MEA) at 30 wt.% was degraded with 7.5 L/min mixed gas (Air/2% CO2/0-200 ppm SO2) under 55 °C. The CO2 loading is 0.4 mol/mol MEA. Degraded samples were analyzed by ion chromatography (IC) and element analyzer. It suggests that SO2 is a potent inhibitor of MEA oxidative degradation by scavenging the active oxide in the solution. A turning point of SO2 concentration exists at approximately 0.67 mM/h in this work, which suggests a discontinuity of the SO2 effects at some critical feed rate of SO2. With SO2 concentration less than 0.67 mM/h, MEA degradation degree changes evidently with SO2 concentration changes, while the excess part of SO2 makes little difference in inhibition effect. The input of SO2 will aggravate the corrosion of the equipment. When the equipment has a good corrosion resistance, the Fe2+ concentration in the solution is suggested to have a linear relationship with SO2 concentration.