A new reactive absorption model using extents of reaction and activities. II. Application to CO2 absorption into aqueous MDEA solutions

Absorption into basic aqueous solutions is widely used for CO2 separation from raw natural gas or from flue gases. This study implements a general steady-state model for reactive gas-liquid absorption. This work expands upon a first case study where the model was applied with the stagnant film theory (Whitman, 1923) to alkaline salts-water-CO2 systems. This second case study uses the resulting Arrhenius expression to examine published CO2 absorption and desorption flux data in MDEA-water-CO2 system. Arrhenius parameters are optimised for the reaction CO2 + MDEA + H2O <-> HCO3- + MDEAH+ with lnk (m(3).mol(-1).s(-1)) = 16.69 - 6385/T (K). Results emphasise the role of CO2 physical solubility representation in reactive absorption model overall performance. Global modelling is needed: kinetic parameters should be used together with all underlying parameters with which they were obtained. The relevance of activity-based modelling is shown, especially at high CO2 absorption/desorption driving force.