REVISED VAPOR-LIQUID-EQUILIBRIUM MODEL FOR MULTICOMPONENT FORMALDEHYDE MIXTURES

Formaldehyde is one of the most important intermediate products of the chemical industry. Due to its high reactivity, it is commonly handled in aqueous or methanolic solutions. In these solutions, formaldehyde is dissolved chemically. Therefore, modeling thermodynamic properties of aqueous and methanolic formaldehyde-containing mixtures require the consideration of chemical reactions and physical effects. A recently published physico-chemical model (Maurer, 1986) for the description of vapor-liquid equilibria of these systems is tested and improved on the basis of about 140 new experimental data points for mixtures containing formaldehyde, water, methanol, and trioxane at temperatures between 320 and 380 K and pressures below 100 kPa. Improvements are achieved by fitting some of those binary interaction parameters, which formerly had to be estimated due to the lack of experimental data. The revised model is able to reliably predict vapor-liquid equilibria in multicomponent formaldehyde-containing mixtures.