Vapor-Liquid Equilibrium of Ethanol + Sulfur Dioxide and Ethanol + Water + Sulfur Dioxide at Six Temperatures

Binary isothermal vapor-liquid equilibrium (VLE) of ethanol and sulfur dioxide (SO₂) at six temperatures (303-353 K) was measured. The systems were modeled using the non-random two-liquid (NRTL)-Hayden-O’Connell (HOC) model. The NRTL parameters were optimized using Barker’s data reduction method. Ternary isothermal VLE of ethanol, water, and SO₂ at six temperatures (303-353 K) was measured. The binary isothermal VLE of SO₂ and water in the dilute range of SO₂ and liquid-liquid equilibrium (LLE) were found in the literature, and the NRTL parameters were optimized for the system. In addition, the isothermal VLE for ethanol and water found in the literature was used to evaluate the default parameters of Aspen Plus and found accurate. The binary LLE of water and SO₂ was essential in modeling the phenomenologically proper phase behavior. With the optimized parameters, it was possible to calculate the LLE and vapor-liquid-liquid equilibrium (VLLE) regions of the ternary system. The comparison of the model and measurements to the literature were presented, and very good accuracy was found.