Development of an Integrated Reaction–Distillation Process for the Production of Methylal

An integrated reaction–distillation process for the production of methylal from aqueous, methanolic formaldehyde solutions is developed. The process consists of a serial connection of a reactor in which the feed is converted to chemical equilibrium by a heterogeneously catalyzed reaction followed by a pressure-swing distillation sequence, in which a heterogeneously catalyzed reactive section as well as a vapor side draw are used. The catalyst is an acidic ion-exchange resin. The process yields methylal in purities over 0.999 g/g; methanol can be recovered in purities over 0.94 g/g, and water is withdrawn in a purity of 0.99 g/g. The conversion of formaldehyde is above 99.9%. The process development is carried out based on steady-state simulations with a model which explicitly accounts for the oligomerization reactions of formaldehyde in aqueous, methanolic formaldehyde solutions. The model is validated by a comparison to experiments that are carried out in a laboratory glass distillation column.