The absorption of CO 2 into chemically reactive solutions at high temperatures

Abstract

Simultaneous absorption and chemical reaction of carbon dioxide in potassium carbonate-bicarbonate buffer solutions was measured, at 80°C. Rates of absorption were catalyzed by addition of water soluble amines to the solution. Addition of methyl-amino ethanol or morpholine enhances the rate of adsorption by factors of 2 to 2·35 at concentrations of 2·5 per cent. The absorption rates measured were correlated with penetration and surface renewal theory. Reaction rate constants, equilibrium constants and mass transfer coefficients for a postulated reaction mechanism are presented for the cases of high temperature absorption with chemical reaction over reaction times of 3–4 hr. Activation energies are presented for the reaction of CO 2 with hydroxyl ion and with amine molecules in solution. Corroboration of the simultaneous reaction mechanism for amine enhancement is seen and extension of the use of surface-renewal theory to higher temperatures and long periods of absorption is confirmed. Mechanism of buffer catalysis by water soluble amines is discussed.