Competitive Absorption−Desorption of Acid Gas into Water−DEA Solutions

Measurements of the CO 2 absorption rate into a diethanolamine (DEA) aqueous solution were made using a Lewis cell to determine the CO 2 −DEA kinetic parameters. The absorption rate was controlled by a gas-side mass-transfer phenomenon. This was achieved by monitoring the total pressure inside the Lewis cell. The gas-side mass-transfer coefficient was deduced from H 2 S absorption measurements in an aqueous solution of DEA. The kinetic rate constant of the reaction of formation of the zwitterion determined in this work is in good agreement with existing literature values. Measurements of the H 2 S absorption rate into a DEA aqueous solution previously loaded with CO 2 showed a competition between H 2 S absorption and CO 2 desorption. A mass-transfer rate model that takes the effects of chemical reactions into consideration enabled these opposite mass transfers to be modeled.