Effect of acids produced by the dissolution of sulfur and nitrogen oxides in the performance of MEA solvent in CO2 capture: Experimental results and modeling

Abstract

Solvent-based CO₂ capture is very important for the mitigation of greenhouse gases. The presence of SO₂ and NO₂ is observed in several types of CO₂-containing industrial flue gases and even small concentrations can cause significant changes in the performance of the solvent. Their effects on the CO₂ solubility have received very little attention. To simulate the effect of dissolution and accumulation of SO₂ and NO₂ acid gases on the CO₂ loading of aqueous ethanolamine (MEA) solutions, H₂SO₄ and HNO₃ were added, as sources of ${\text{NO}}_3^{-}$ and ${\text{SO}}_4^{-2}$ anions, respectively. The CO₂ solubility in 30 % wt. aqueous MEA solutions containing 2.9 % wt. H₂SO₄ with and without 1.8 % wt. HNO₃ was experimentally measured using a pressure decay method at 313, 333 and 353 K and approximately 5–500 kPa. In both cases, it is revealed that the addition of H₂SO₄ and HNO₃ substantially decreases the CO₂ solubility. In addition, the modified Kent-Eisenberg model was used to predict the CO₂ solubility in all systems and at all the studied conditions. The model predictions are in satisfactory agreement with the experimental data presenting Average Absolute Deviations between 4.8 and 6.8 % in all cases.