Comprehensive mass transfer and reaction kinetics studies of CO2 absorption into aqueous solutions of blended MDEA–MEA

In the present work, the reaction kinetics and mass transfer performance of CO2 absorption into aqueous solutions of blended MDEA–MEA solutions were comprehensively studied. The reaction kinetics was investigated using a laminar jet absorber in terms of a second order reaction rate constant and enhancement factor. The mass transfer performance was evaluated experimentally in a lab-scale absorber packed with high efficiency DX structured packing in terms of CO2 concentration profile and over all mass transfer coefficient (KGav). The experiments were conducted over the MDEA/MEA concentrations of 27/3, 25/5, and 23/7 wt% MDEA/wt% MEA (which equivalent to MDEA–MEA molar ratios of 2.3/0.5, 2.1/0.8, and 1.95/1.16 M, respectively). It was found that kMEA   was successfully extracted and can be expressed as: kMEA=(5.127×108)expkMEA=(5.127×108)exp-3373.8T. The results also show that the operating parameters (i.e., MDEA–MEA blended ratio, temperature, and CO2 loading) affect both the reaction kinetics and mass transfer performance significantly. Lastly, the MDEA–MEA blended ratio of 1.95/1.16 provided the highest reaction kinetics and mass transfer performance among the three concentrations investigated in this study.

The graphic illustrates the CO2 absorption inside packed column, where CO2 contacts with reactive amine solvents. CO2 is represented by the white cloudy gas, while reactive amine solvent is represented by the green liquid.The graphic clearly and visually shows: (i)CO2 and reactive liquid solvent contact in the absorption packed column.(ii)The packing generates more gas-liquid contact area by letting reactive liquid solvent spread over the packing and creating droplets of the reactive liquid solvent. The more contact area will lead to the higher CO2 absorption performance.(iii)The randomly alignment of the packing in the absorption packed column.We believe this graphic will lead to the more understanding on CO2 absorption behavior using reactive amine solvents in the packed column.Figure optionsDownload as PowerPoint slideHighlights
► Mass transfer and reaction kinetics of MDEA–MEA was comprehensively studied.
► Considering effect of blended ratio, temperature, liquid flow rate, CO2 loading.
► kMEA was successfully extracted and in good agreement with the literature values.
► Reaction kinetics can successfully explain mass transfer behavior.