The isobaric vapor liquid equilibrium (VLE) data for two binary systems of ethylene glycol (EG) + neopentyl glycol (NPG) and NPG + para-xylene (PX) have been measured under pressure of 101.3 kPa, respectively. The thermodynamic consistency of the experimental isobaric VLE data was tested by means of Herington area test. Meanwhile, the experimental isobaric VLE data have been satisfactorily correlated with Wilson, NRTL, and UNIQUAC models. A conventional azeotropic distillation process has been designed to achieve high-purity products based on preceding results. The product purities of EG and NPG can both achieved at 99.9 mol % with minimal total annual cost (TAC) through sequential iterative optimization procedure.