Detailed modeling of the chemisorption of CO2 into NaOH in a bubble column

Bubble column reactors with or without circulation loops are marked by complex dynamic interactions of hydrodynamics, mass transfer, and reactions. In this study, we focus on a reaction system, in which reaction enhanced mass transfer results in large temporal and spatial variations of bubble sizes and of gas hold-up and interfacial area. The reactor behavior is investigated by means of experimental observation and numerical simulation. The chemisorption of carbon dioxide into an aqueous solution of sodium hydroxide was chosen as a fast model reaction. A one-dimensional, dynamic model was developed in order to predict the start-up behavior of the reaction system in the bubble column. The change of the bubble size distribution due to carbon dioxide consumption has been incorporated by means of a population balance equation. The numerical simulations of the reaction progress for different reaction and operating conditions were compared with experimental results. A reasonable qualitative agreement was obtained. Both simulation and experimental studies reveal a high sensitivity of the dynamic reactor behavior against small variations in the hydrodynamic, mass transfer, and kinetic parameters.