Isobaric and Isothermal Vapor–Liquid Equilibria for the Binary System of Water + Formic Acid at 99.41 kPa, 388.15 K, and 398.15 K

Abstract

In the process of methyl formate hydrolysis, it is necessary to separate water from formic acid. Rectification is one of the suitable methods to achieve this. However, vapor–liquid equilibrium data are essential for the rectification unit design, and these are either not available in the literature at all, or when available are significantly scattered. The water + formic acid binary system forms a maximum-boiling azeotrope, and its behavior is nonideal both in liquid and vapor phases. In this paper, we are presenting the vapor–liquid equilibrium data for the above-specified binary system. The isobaric and isothermal data have been measured under atmospheric pressure and at the temperatures of 388.15 and 398.15 K. We have found, based on the value of the average absolute deviation, that the UNIQUAC–Hayden O’Connell combined model is the best fitting for the measured data plotting. On the basis of this combined model, we are able to estimate the azeotropic point composition at elevated pressure levels. In addition, our data can be reliably used in the future design of a rectification unit.