Phase Equilibria of CO₂-Water and CO₂-Brine at High Temperatures: From Monte Carlo Simulations to the Equation of State

Author(s)

Coelho, Felipe Mourao ; Franco, Luis Fernando Mercier ; Firoozabadi, Abbas

• Document type: Journal article
• Source: Industrial & Engineering Chemistry Research; v. 64, n. 16, p. 14-pg., 2025-04-11.

Abstract

Accurate modeling of density and CO2 partitioning in the CO2-water and CO2-brine systems over a wide pressure and temperature range is of high interest in many subsurface processes. We parametrize a new set of CPA and eCPA equations of state accounting for the CO2-H2O cross-association. The CO2-water phase diagrams and the CO2 solubility in NaCl brine are reproduced up to 700 K and 6 m of salinity. The density of CO2 in aqueous mixtures is predicted accurately, including the effect of CO2 dissolution, which may increase or decrease the density depending on conditions. From Monte Carlo simulations, the SPCE-EPM2 force field with optimized unlike parameters reproduces the high-temperature phase diagram without polarization corrections. In this work, our knowledge of the thermodynamics of CO2 in aqueous mixtures is expanded by providing a model for geothermal and CO2 sequestration conditions. (AU)

• FAPESP's process: 20/13300-6 - Molecular dynamics simulations for studying equilibrium properties of confined mixtures
• Grantee: Felipe Mourão Coelho
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 18/02713-8 - Molecular dynamics of confined fluids: equilibrium and transport properties
• Grantee: Luís Fernando Mercier Franco
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 21/13068-9 - Thermodiffusion of CO2 in water: the Impact of the geothermal gradient in the carbon sequestration within deep saline aquifers via molecular simulation
• Grantee: Felipe Mourão Coelho
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)