Measurement and Modeling of Sulfur Dioxide (SO₂)–Dimethyl Ether, SO₂–1,4-Dioxane and SO₂–Polyethylene Glycol Dimethyl Ether Binary System Bubble Point Pressures at (288–308) K

Gas capture of pollutants such as SO₂ that occur in flue gas, heavy oil refining and metallurgical processes is a necessary and important topic for the environment. In this work, bubble point pressures are reported for SO₂–dimethyl ether at (298.15–323.15) K, SO₂–1,4-dioxane at (293.15–298.15) K, and SO₂–polyethylene glycol dimethyl ether (PEGDME, M_w = 240) at (288.15–323.15) K for the purpose to understand SO₂–ether group interactions. Experimental bubble point pressures were lower than those expected from Raoult's law and showed strong interactions between SO₂ and functional ether group. Experimental data were correlated with Flory–Huggins and ASOG group contribution models. Only the two groups, SO₂ and –CH₂OCH₂–, and were considered in the ASOG model with the group pair interaction parameters being determined from data at the azeotropic point of the SO₂–dimethyl ether system. The ASOG group contribution model was found to be more reliable for calculation than the Flory–Huggins model and gave average relative deviations (ARDs) of 2.25% and 7.05% for the bubble point pressures of the SO₂–dimethyl ether and SO₂-1,4-dioxane systems, respectively. A steric factor, f-CH2OCH2- = 0.589 for the –CH₂OCH₂– group in PEGDME allowed the ASOG model to calculate bubble point pressures with an ARD of 5.61% for the SO₂–PEGDME system. PEGDME and related polyethers can be considered as possible SO₂ gas capture solvents.