Experimental and Estimation of Vapor-Liquid Equilibria in AqueousElectrolyte System: CO2-K2CO3-MDEA+DEA-H2O

Abstract

Absorption with chemical reaction process of CO2 gas using K2CO3solution or known as hot potassiumcarbonate promoted with amine was widely used in many chemical industries. DEA and MDEA mixture wasproposed as promoter. Vapor-liquid equilibrium (VLE) data of CO2-K2CO3-MDEA+DEA-H2O system areneeded for rational design and optimal operation of CO2 removal unit. The purpose of this research is todertermine solubility data of CO2 gas in aqueous solution of potassium carbonate with DEA and MDEA as apromotor at various temperatures of 30-50°C with 30% K2CO3, 1-3% MDEA and 1-3% DEA. The CO2solubility is very important property when establishing thermodynamics models for the VLE. In order to obtainthe CO2 solubility, the normal procedure is to use the N2O analogy since the CO2 solubility cannot be directlymeasured. Solubility was measured volumetrically in absorption flask using a shaking waterbath. The increase ofDEA concentration in solution gives higher Henry’s constant or lower gas solubility. It also makes the empiricalcorrelation between Henry’s constant andtemperature in various concentrations of MDEA and DEA. The resultsof N2O analogy experiment were used to calculate the vapor liquid equilibria of CO2-K2CO3-MDEA+DEA-H2Osystem by using the electrolyte NRTL model. The model gives a good representation of the experimental VLEdata for CO2 partial pressures with Root Mean Square Deviation (RMSD) of 5.93%.