Three-phase crystallization for purification of acrylic acid from acrylic/propionic acid mixture

A new separation technology, three-phase crystallization (TPC), was utilized to purify acrylic acid (AA) from a binary liquid mixture comprising AA and propionic acid (PA). The solid–liquid equilibrium data of AA/PA mixture reported in the literature were adopted to recover the activity coefficients of the liquid mixture; and, subsequently, the vapor–liquid equilibrium conditions of AA/PA mixture were predicted using Raoult's law and the Wilson equations for the recovered activity coefficients. The reported solid–liquid equilibrium data and the predicted vapor–liquid equilibrium conditions were coupled to determine the three-phase transformation conditions of AA/PA mixture, which were employed to conduct the batch TPC experiments. Upon conclusion of the TPC, the yield and purity were measured to estimate the amount of the AA crystals and volume of the liquid mixture retained in the overall final product, respectively.