CO 2 absorption into aqueous mixtures of diglycolamine ® and methyldiethanolamine

Abstract

Rates of CO 2 absorption into mixtures of methyldiethanolamine (MDEA) and β, β′-hydroxyaminoethyl ether (diglycolamine ®, DGA) were measured in a wetted-wall column reactor at 25–100°C with CO 2 loading from 0.015 to 0.55 mol CO 2/mol of reactive solvent. The mass transfer rates were modeled by approximate surface renewal theory with time-mean concentrations and fluxes. The rates in the mixtures were relatively insensitive to the reaction rate parameters, but strongly dependent on the diffusivity of liquid-phase reactants and reaction products and on thermodynamic interaction parameters, especially at temperatures greater than 60°C. Regressed diffusion coefficients for the liquid-phase reactants and reaction products are comparable to previously measured values for similar molecules. The regressed values for the electrolyte interaction parameter of water–carbamate salt are comparable to reported values of the equivalent parameter for the system monoethanolamine–MDEA.