Modelling Vapour-liquid Equilibria Of CO2 Over Aqueous PZ Solution

Abstract

Regenerative chemical absorption of the acid gases into solutions of alkanolamines is widely used for gas treating. Nowadays the addition of an accelerator like piperazine (PZ), to aqueous N-methyldiethanol amine (MDEA) has found widespread application in the removal and absorption of CO2 from process gases. Representation of the experimental data with a model is required, so that one can systematically correlate and predict the vapor-liquid equilibria (VLE) of these systems. Present study is focused on modeling the solubility of CO2 over aqueous PZ solution following the approach of Kent and Eisenberg, considering apparent equilibrium constants for the chemical reactions. The develop model has been validated with CO2 solubility over 0.2 M and 0.6 M piperazine solutions in the temperature range 298-343 K. The model predictions of the VLE of CO2 in 2 and 4 M aqueous piperazine solutions over the temperature range 313- 393 K are in excellent agreement with the experimental results from open literature.