Thermodynamic Analysis of CO2 Absorption in Aqueous MDEA-PZ Solution Using ELECNRTL and ENRTL-RK Models

Abstract

Carbon capture and storage using chemical absorption is a viable method for reducing CO₂ emissions from the industrial sector. Thermodynamic analysis of MDEA-PZ aqueous alkanolamine solution is of paramount importance to better simulate and improve the efficiency of CO₂ capture processes. In this study, we use the Aspen Plus simulator (V12.1) to compare the theoretical differences and the regression results of the two-liquid activity coefficient models ELECNRTL and ENRTL-RK in terms of CO₂ solubility. The quaternary system CO₂-MDEA-PZ-H₂O vapor-liquid equilibrium (VLE) data found in the open literature are first collected. After excluding anomalous points according to some criteria, 521 confirmed data ranging from 40 °C to 120 °C are then used to regress the binary interaction parameters of molecule-molecule and molecule-electrolyte pairs for both models using the maximum likelihood method. The fitting results show an accuracy enhancement of 34 % for ELECNRTL and 68 % for ENRTL-RK compared to the Aspen default models. The regressed models can be used to improve the accuracy of absorber and stripper simulations in CO₂ capture processes.