Kinetics of Absorption of CO₂ in Concentrated Aqueous Methyldiethanolamine Solutions in the Range 296 K to 343 K

The kinetics of CO 2 absorption by aqueous solutions of methyl diethanol amine (MDEA) were measured in the temperature range (296−343) K and MDEA concentration range (830−4380) mol·m - 3 (10−50 mass %). A thermoregulated constant interfacial area Lewis-type cell was operated by recording the pressure drop during batch absorption. The kinetic results are in agreement with a fast regime of absorption according to film theory. MDEA depletion at the interface has a significant effect on the kinetics at the CO 2 pressures (100 to 200 kPa) studied in this work, especially at low temperatures and low MDEA concentrations. Considering only the reaction between CO 2 and MDEA, the CO 2 absorption appears as a first-order reaction with respect to MDEA. The activation energy found for the reaction between CO 2 and MDEA is 45 kJ·mol - 1, but this value depends significantly (by about 10% in the worst case) on the vapor−liquid equilibrium data used.