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.
Cyclohexanol is an important intermediate in production of adipic acid and ε-caprolactam. On the industrial scale, cyclohexanol is produced by several methods that suffer from considerable drawbacks, such as a low conversion of the initial substance, low selectivity of the process, or explosion risks in the oxidation unit. To design a new process of indirect hydration of cyclohexene in the presence of formic acid, it is necessary to know the given system properties. In this paper, the data of liquid−liquid equilibrium (LLE) are presented for the system of cyclohexanol + water + cyclohexyl formate under atmospheric pressure and within a temperature range from 298.2 to 338.2 K. The experiments were conducted in a temperature-controlled glass cell and the received data were correlated with the nonrandom two-liquid (NRTL) and universal quasichemical equations in order to obtain binary interaction parameters describing LLE of the given system. The measured data accuracy was specified by the Bachman and Othmer−Tobias equations. The data fitting accuracy was evaluated by the use of the calculated average absolute deviation and the root-mean-square-error values. The NRTL model obtained in this work was compared to a previous published model. The model obtained in this work significantly improves the prediction of ternary data at elevated temperatures.
The efficiency of industrial column packings is commonly tested by standard hydrocarbon mixtures. However, a reduced efficiency value is often observed, particularly during distillation of aqueous mixtures. In this paper, distillation experiments with various binary mixtures were carried out on different column packings to evaluate relative separation efficiencies of mixtures for each packing material. Each of the binary mixtures, which comprised heptane–methylcyclohexane, ethanol–water, morpholine–water, and acetic acid–water, was distilled under atmospheric pressure and total reflux ratio on column packings that were made of PTFE, ceramic, zirconium metal, and inox steel 316. According to the results, aqueous solutions of morpholine and acetic acid generally exhibited low relative separation efficiency (in comparison with standard mixture of heptane–methylcyclohexane), ranging between 40 % and 80 %. The highest relative efficiencies were observed with packings made of steel and ceramic. These observations will be useful for the future design of distillation columns, especially for aqueous solutions.
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