CO2 absorption into aqueous mixtures of diglycolamine (R) and methyldiethanolamine

Rates of CO2 absorption into mixtures of methyldiethanolamine (MDEA) and be ta,beta'-hydroxyaminoethyl ether (diglycolamine(R) DGA) were measured in a wetted-wall column reactor at 25-100 degreesC with CO2 loading from 0.015 t o 0.55 mol CO2/mol of reactive solvent, The mass transfer rates were modele d by approximate surface renewal theory with time-mean concentrations and f luxes. The rates in the mixtures were relatively insensitive to the reactio n rate parameters, but strongly dependent on the diffusivity of liquid-phas e reactants and reaction products and on thermodynamic interaction paramete rs, especially at temperatures greater than 60 degreesC. Regressed diffusio n coefficients For the liquid-phase reactants and reaction products are com parable to previously measured values for similar molecules. The regressed values for the electrolyte interaction parameter of water-carbamate salt ar e comparable to reported values of the equivalent parameter for the system monoethanolamine-MDEA. (C) 2000 Elsevier Science Ltd. All rights reserved.