Process analysis of pressure-swing distillation for the separation of formic acid–water mixture

The separation of the binary mixture formic acid–water is difficult by conventional distillation since it forms maximum boiling azeotrope at atmospheric pressure. The separation by altering the column pressure is possible if the pressure has a considerable effect on the azeotropic composition. The previous studies of vapor–liquid equilibrium of binary system formic acid–water have shown that the azeotrope is sensitive to pressure. This work aims to study the effect of the concentration of formic acid in the binary mixture formic acid–water on the ease of separation using two distillation columns operating at different pressures, which are determined by the composition variation of the azeotrope with pressure. The process consists of two-column, the first column operating at pressure of 1.96 bar to recover water and the second column operating at pressure of 0.267 bar to recover formic acid. The best operating parameters have been determined to get the high recovery ratio of formic acid.