Absorption and desorption mass transfer rates in chemically enhanced reactive systems. Part II: Reverse kinetic rate parameters

The forward and reverse kinetic rate parameters have been determined for CO2 absorption and desorption mass transfer processes in aqueous 2.0 M MDEA solutions at temperatures of 298.15, 313.15, and 333.15 K and the loading of CO2 ranging from 0 to 0.8. The derived kinetic rate parameters have been based on the results of experimental work in a controlled environment in a batch operated stirred tank reactor. In a continuous effort to describe the fundamentals of gas-liquid desorption processes [1,2], it has within applied experimental conditions been shown that; (1) the forward and reverse kinetic rate parameters derived by an analytical relation based on the Higbie penetration theory are within 25% of those numerically derived by a system of partial differential equations based on the Higbie penetration theory. The analytical relations were based on reversible reactions of finite rate in solutions of different CO2 loadings and diffusivities, (2) the reaction order of the forward reaction in solutions of different CO2 loadings is close to unity, and in agreement with the proposed reaction mechanism, (3) Arrhenius type of equations already developed for correlation of forward kinetic rate parameters were further modified in order to sufficiently correlate reverse kinetic rate parameters. These types of equations thus form a tool for the correlation and prediction of reverse kinetic rate parameters for engineering purposes and (4) the experimentally determined forward and reverse kinetic rate parameters were accordingly found to be related by an overall temperature dependent chemical equilibrium constant. (C) 2012 Elsevier B.V. All rights reserved