Thermodynamic study of binary systems containing sulphur dioxide: Measurements and molecular modelling

In the present work, we report isothermal vapour–liquid equilibrium data for two binary systems: nitrogen–sulphur dioxide and oxygen–sulphur dioxide at four temperatures (323.15, 343.15, 373.15, and 413.15 K) and pressures up to 85 MPa. These data were simultaneously obtained from experimental measurements and molecular simulations. The compositions of coexisting phases were experimentally determined using an apparatus based on the “static-analytic” method. At the same time, Gibbs ensemble Monte Carlo (MC) simulations were performed on these binary mixtures, using force fields based on pure component properties. An original force field is proposed for sulphur dioxide molecule, involving three Lennard–Jones centres and three electrostatic charges. The experimental and simulation results appear in good agreement, allowing reliable and accurate predictions at higher pressures with molecular simulations.

Research highlights
► VLE of nitrogen–sulphur dioxide and oxygen–sulphur dioxide at four temperatures.
► Experimental measurements and Gibbs ensemble Monte Carlo (MC) simulations.
► Compositions of coexisting phases through the “static-analytic” method.
► Original force field proposed for sulphur dioxide molecule.
► Experimental and simulation results are in good agreement.