Phase Equilibrium in Formaldehyde Containing Multicomponent Mixtures: Experimental Results for Fluid Phase Equilibria of (Formaldehyde + (Water or Methanol) + Methylal)) and (Formaldehyde + Water + Methanol + Methylal) and Comparison with Predictions

Methylal (also known as dimethoxymethane and formaldehyde dimethyl acetal) is a side product of the production of polyacetal plastics from formaldehyde, which has to be removed in downstream processing. The design of the separation equipment requires a verified model for the vapor−liquid-phase equilibrium. New experimental results are presented for the vapor−liquid and liquid−liquid equilibrium of the ternary system (formaldehyde + water + methylal) and for the vapor−liquid equilibrium of the ternary system (formaldehyde + methanol + methylal) and of the quaternary system (formaldehyde + water + methanol + methylal). New experimental results and the literature data are compared with prediction results.