Carbon dioxide absorption, desorption, and diffusion in aqueous piperazine and monoethanolamine

This work includes wetted wall column experiments that measure the CO 2 equilibrium partial pressure and liquid film mass transfer coefficient (kg') in 7, 9, 11, and 13 m MEA and 2, 5, 8, and 12 m PZ solutions. A 7 m MEA/2 m PZ blend was also examined. Absorption and desorption experiments were performed at 40, 60, 80, and 100°C over a range of CO2 loading. Diaphragm diffusion cell experiments were performed with CO 2 loaded MEA and PZ solutions to characterize diffusion behavior. All experimental results have been compared to available literature data and match well.;MEA and PZ spreadsheet models were created to explain observed rate behavior using the wetted wall column rate data and available literature data. The resulting liquid film mass transfer coefficient expressions use termolecular (base catalysis) kinetics and activity-based rate expressions. The kg' expressions accurately represent rate behavior over the very wide range of experimental conditions. The models fully explain rate effects with changes in amine concentration, temperature, and CO2 loading. These models allow for rate behavior to be predicted at any set of conditions as long as the parameters in the kg' expressions can be accurately estimated.;An Aspen PlusRTM RateSep(TM) model for MEA was created to model CO2 flux in the wetted wall column. The model accurately calculated CO2 flux over the wide range of experimental conditions but included a systematic error with MEA concentration. The systematic error resulted from an inability to represent the activity coefficient of MEA properly. Due to this limitation, the RateSep(TM) model will be most accurate when fine-tuned to one specific amine concentration. This Aspen PlusRTM RateSep(TM) model allows for scale up to industrial conditions to examine absorber or stripper performance.