PURIFICATION OF FORMALDEHYDE BY DISTILLATION

To develop a new technology for the purification of formaldehyde from formalin by a distillation method, the vapor-liquid equilibria of form aldehyde water binary systems and the vapor-liquid equilibria of forma ldehyde water systems in the presence of diluent were investigated. It was shown by calculation that in some cases, when the concentration o f diluent is high, the volatility of formaldehyde is always higher tha n that of water and that these calculations are in good agreement with experimental data. Based on this principle, the purification of forma ldehyde by an extractive distillation method was established.