Comparative kinetics of carbon dioxide absorption in unloaded aqueous monoethanolamine solutions using wetted wall and string of discs columns

The kinetics of the reaction between carbon dioxide and unloaded aqueous solutions of monoethanolamine (MEA) were investigated over the temperature range from 298 to 343 K, MEA concentration range from 0.5 to 5 mol/L in both a wetted wall column reactor (WWC) and a string of discs contactor (SDC). Earlier kinetic studies in the CO2–MEA–H2O system are reviewed and compared first based on the experimental data alone. The comparisons are made for different types of apparatuses to establish whether the recent literature data and the data from this study are consistent with each other. Then the various ways of interpreting the data are reviewed and compared. Finally, the new data are interpreted using the pseudo first order assumption and including gas phase mass transfer resistance. The direct mechanism was used for the interpretation and the reaction order was found to be in the range of 1.36–1.51 with respect to concentrations. A model was developed for the kinetic rate constant explaining the broken order behavior.

► The kinetics in CO2–MEA–H2O was studied over 298–343 K, 0.5–5 M in WWC and SDC.
► Literatures are reviewed and comparisons are made by different ways.
► The experimental data are interpreted using pseudo first order assumption.
► The broken order behavior was found with the reaction order.
► A direct mechanism model was developed for kinetic rate constant.