Solubility Study of Binary Systems Containing Sulfur Dioxide and Water: A Combination of Raman Spectroscopy and Monte Carlo Molecular Simulation

Abstract

Carbon Capture, Utilization and Storage (CCUS) is one of the mitigation approaches that can be used to control CO2 emissions into the atmosphere and to limit global warming. The CO2 stream injected underground may contain small amounts of associated gaseous components such as SO2. One of the key parameters needed to predict the physical and chemical evolution of the storage is solubility. Unfortunately, there is only scarce information on hazardous binary systems containing such gases. The purpose of this study is to acquire new thermodynamic data on SO2 under geological conditions of pressure and temperature. The solubility of SO2 in water is measured by Raman spectroscopy using high-pressure optical cells and capillary capsules after a calibration based on Monte Carlo (MC) molecular simulation and literature data. New solubility data are measured in the temperature range 20°C–120 °C and pressures up to 25 bar. By introducing an empirical temperature-dependent and temperature-independent binary interaction coefficient kij between water and sulfur dioxide, it is possible to obtain a good agreement between experiments and MC simulations in both liquid-vapor and liquid-liquid conditions.

Keywords: CO2 Storage, thermodynamics, SO2 solubility, Raman spectroscopy, molecular simulation