Vapor−Liquid and Liquid−Liquid Equilibria in Binary and Ternary Mixtures of Water, Methanol, and Methylal

Methylal is a byproduct in industrial processes, for example, in the production of polyacetal plastics. In such processes aqueous solutions of methylal and methanol have to be treated by distillation. This contribution reports experimental results for the phase equilibrium in such mixtures: vapor−liquid equilibrium of the binary systems (water + methylal) at 284 ≤ T /K ≤ 388 and (methanol + methylal) at 303 ≤ T /K ≤ 348, and of the ternary system (water + methanol + methylal) at 303 ≤ T /K ≤ 363, as well as liquid−liquid equilibrium of (water + methylal) and (water + methanol + methylal) at 273 ≤ T /K ≤ 313. Furthermore, new experimental results are reported for the vapor pressure of methylal at 318 ≤ T /K ≤ 357. The new experimental phase equilibrium data are correlated using the UNIQUAC model to describe the Gibbs excess energy of the liquid mixtures.