Phase Equilibria of CO2 and n-Alkanes in Bulk and Confined Space Using Parallelized Wang-Landau Transition-Matrix Monte Carlo Simulations

Published

April 6, 2025

Author(s)

Jilong Xu, Harold Hatch, Vincent Shen, Zhehui Jin

Abstract

The accurate and fast simulation of CO2 and n-alkanes phase equilibria is crucial for guiding their industrial applications. We use the Wang−Landau Transition-Matrix Monte Carlo (WL-TMMC) with the Free Energy and Advanced Sampling Simulation Toolkit (FEASST) software to compute the vapor-liquid equilibria (VLE) of CO2-methane and CO2-hexane systems in both bulk and confined spaces. The bulk-phase simulation results are compared with literature data and constant volume Gibbs Ensemble (NVT-GEMC) results, with relative errors less than 5%. For confined systems, the results are compared with gauge-GCMC and pore-pore GEMC methods, with relative errors less than 8%. Notably, the WL-TMMC method exhibits significant advantages in computing VLE for confined spaces. It requires only a single simulation to determine a pair of VLE points without being constrained by pre-specified chemical potentials or pore geometry. Furthermore, the method provides free energy information for different fluid states, enabling the construction of a complete van der Waals loop from a single simulation. In conclusion, we demonstrate that the WL-TMMC method in FEASST is a robust and reliable tool for studying CO2-n-alkane VLE.

Citation

Energy & Fuels

Volume

39

Issue

15

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acs.energyfuels.5c00420

Local Download

Keywords

phase equilibria, thermodynamics, statistical mechanics, Monte Carlo

Citation

Xu, J. , Hatch, H. , Shen, V. and Jin, Z. (2025), Phase Equilibria of CO2 and n-Alkanes in Bulk and Confined Space Using Parallelized Wang-Landau Transition-Matrix Monte Carlo Simulations, Energy & Fuels, [online], https://doi.org/10.1021/acs.energyfuels.5c00420, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959493 (Accessed October 21, 2025)