Chemical and Phase Equilibria in the Reaction between NO and O₂ in the Presence of Water and CO₂ at 298.15 K up to 3 MPa

Abstract

New experimental data for cosolubility of carbon dioxide, nitric oxide, and nitrogen dioxide produced from the reaction in situ between nitric oxide and dioxygen in pure water at 298.15 K and up to 3 MPa are presented in this work. These data are essential to develop and validate thermodynamic models for CO2 and other gases capture and storage processes. In this work, measurements of carbon and nitrogen oxide solubilities in water are achieved; the liquid phase composition at the thermodynamic equilibrium was determined by analytical methods (ion chromatography), pH-metric titration, and a static synthetic method, and the gaseous phase composition was determined by two infrared spectrometers. The experimental apparatus and the analytical procedure were validated by studying the CO2 + water systems and comparing the experimental measurements with the literature data. On the other hand, the measurements of NO2 + water systems are original and do not exist in the literature. In order to study the behavior of the nitrogen dioxide in water, a suitable reaction mechanism was carefully chosen to predict the composition of the different nitrogen species (NO, NO2, N2O3, N2O4, HNO2, H+, NO2 –, HNO3, and NO3 –.) in the aqueous medium at 298.15 K. Then, a Henry constant for the studied nitric oxide systems was calculated. Some difficulties have been encountered in the stabilization of the nitrogen dioxide partial pressure due to its metastable conditions; therefore, data related to the Henry constant of this compound will not be reported.