Prediction Using UNIFAC Model: Vapor-Liquid Equilibria for N-Propanol + Water System with the Addition of Ethylene Glycol Oligomers as Entrainer at 50.65 and 101.3kPa

Due to the depletion of fossil fuels, renewable and cleaner biofuels are becoming more popular to displace fossil fuels. N-propanol is the preferred alternative fuel because it can be produced by fermentation from renewable biomass. However, fermented products are always mixed with water. The mixture of N-propanol and water creates a minimum azeotrope. Extractive distillation (ED) is a method used in industry to separate azeotropes. ED is a separation technique that modifies the relative volatility of the original mixture's components by adding a third component known as an entrainer. Vapor-liquid equilibrium (VLE) data and the thermodynamic model parameters are needed as the basis for the design of the extractive distillation column and optimizing the separation process. In this study, VLE data were predicted using the UNIFAC model for the ternary systems of n-propanol (1) + water (2) + ethylene glycol oligomers (3) as an entrainer at 50.65 and 101.3 kPa. This prediction method aims to determine the best entrainer and operational conditions in the ED process. The strength of ethylene glycol oligomers as an entrainer to shift and break n-propanol azeotrope in the order of ethylene glycol > diethylene glycol > triethylene glycol > tetraethylene glycol. A 70% mole of the ethylene glycol oligomer fraction is needed as an entrainer to properly separate the n-propanol and water mixture at atmospheric pressure.