Determination of mass transfer coefficient of co2 in solutions of monoethanolamine, 2-(methylamino)ethanol and dimethylaminoethanol in packed absorption column

Abstract

In this study, mass transfer of two new solvents, 2-MAE and DMAE were studied with various factors affecting mass transfer coefficient in comparison with MEA. Effect of solvent types, CO2 inlet loading 0.0, 0.1 and 0.2 mol/mol, solvent concentration 3, 4 and 5 kmol/m3, solvent flow rate 5.3, 10.6 and 15.9 m3/(m2·h) and CO2 content 13-15 v/v% in gas feed were investigated. In all cases, 2-MAE performed highest mass transfer rate among others. The highest mass transfer rate was 1.2656 kmol/(kPa·h·m3) for the case that CO2 inlet loading 0.0 mol/mol, solvent concentration 3 kmol/m3, solvent flow rate 10.6 m3/(m2·h) and CO2 content in gas feed was 15 v/v% which higher than that of MEA and DMAE at 0.4638 and 0.0215, respectively. The most influencing factor on rate of mass transfer was the reactant concentration which promoted forward rate of reaction and consequently reduced time required for absorption of dissolved CO2. Therefore, an increase in enhancement factor leads to an increase in overall mass transfer coefficient. In this study, DMAE which is a tertiary amine was not able to reach 100% CO2 removal efficiency due to the sluggish rate of reaction in carbonic formation step. Though there are more subjects needed to be investigated before further implementation in real CO2 capture plants, 2-MAE showed a positive possibility to be a candidate for solvent selection.