Solubility of sulfur compounds in commercial physical solvents and an ionic liquid from Monte Carlo simulations

Journal article (2017)

Authors

S.H. Jamali Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering
M. Ramdin Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering
T. Becker Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering
Ariana Torres-Knoop Universiteit van Amsterdam
D. Dubbeldam Universiteit van Amsterdam
W. Buijs Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering
T.J.H. Vlugt Engineering Thermodynamics - Mechanical, Maritime and Materials Engineering
Research Group
Engineering Thermodynamics (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2017 S.H. Jamali, M. Ramdin, T. Becker, Ariana Torres-Knoop, D. Dubbeldam, W. Buijs, T.J.H. Vlugt
DOI
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https://doi.org/10.1016/j.fluid.2016.11.015
Carbon capture Natural gas Molecular simulation Acidic gases Osmotic ensemble Sulfur compounds
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Published Date

2017

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Engineering Thermodynamics

Abstract

Natural gas, synthesis gas, and flue gas typically contain a large number of impurities (e.g., acidic gases), which should be removed to avoid environmental and technological problems, and to meet customer specifications. One approach is to use physical solvents to remove the acidic gases. If no experimental data are available, the solubility data required for designing the sweetening process can be obtained from molecular simulations. Here, Monte Carlo (MC) simulations are used to compute the solubility of the gas molecules, i.e., carbonyl sulfide, carbon disulfide, sulfur dioxide, hydrogen sulfide, methyl mercaptan, carbon dioxide, and methane in the commercial solvents tetraethylene-glycol-dimethyl-ether (Selexol), n-methyl-2-pyrrolidone, propylene carbonate, methanol (Rectisol), and the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]). Henry coefficients of the gases in the investigated solvents are obtained from the computed solubilities. The ratio of Henry coefficients is used to compute ideal selectivities of the solvents. The solubilites and selectivities computed from MC simulations are compared with available experimental data. Some guidelines are provided to remove acidic gases using the investigated solvents. Rectisol is the best solvent for acid gas removal, but it should be used at low temperatures. Selexol and the ionic liquid have similar selectivity of sulfur compounds with respect to methane and may be used at elevated pressures and temperatures since both have low vapor pressures. The solubility of carbon disulfide, sulfur dioxide, and methyl mercaptan in these solvents is the highest. Hence, these components can be removed easily prior to hydrogen sulfide, carbonyl sulfide, and carbon dioxide in a pre-absorber.