Elsevier

Fluid Phase Equilibria

Volume 382, 25 November 2014, Pages 65-69
Fluid Phase Equilibria

Liquid–liquid equilibria for ternary system water + acetic acid + cyclohexanone at (293.2–323.2) K

https://doi.org/10.1016/j.fluid.2014.08.034Get rights and content

Highlights

  • LLE data for water + acetic acid + cyclohexanone were measured.

  • The LLE data were measured at (293.2–323.2) K and at atmospheric pressure.

  • Reliability of the LLE data were checked by both Othmer–Tobias and Bachman

  • equation.

  • UNIQUAC and NRTL model were used to correlate the experimental LLE data.

Abstract

Liquid–liquid equilibria (LLE) for the ternary system water + acetic acid + cyclohexanone was studied at (293.2–323.2) K and at atmospheric pressure. The immiscibility region was found to be relatively small and not sensitive to the change of temperature. The Othmer–Tobias equation and the Bachman equation were both used to check the reliability of the obtained experimental tie-line data. The experimental results were correlated with both the NRTL and the UNIQUAC activity coefficient models. The calculated results showed good agreement with the experimentally determined ternary LLE data. The root mean square deviations (RMSD) obtained by comparing the calculated and experimental two-phase compositions are 0.72% for the UNIQUAC model and 0.40% for the NRTL model. The obtained interaction parameters can be used in the calculation of LLE for the ternary system water + acetic acid + cyclohexanone as well as for the design and optimization of the related separation process.

Introduction

Adipic acid (AA), the main precursor for nylon 6,6 and polyurethane plastics, is of great importance to industry [1], [2]. Commercially it is manufactured by the oxidation of the binary cyclohexanol + cyclohexanone mixtures (known as KA oil), using nitric acid as the oxidant. This process leads to a substantial amount of undesirable nitrous oxide (N2O) emissions (0.3 kg N2O per kg adipic acid), which is environmentally unfriendly and is commonly regarded as the dominant global warming and ozone-depletion substance [3].

In recent years, an alternative non-HNO3 route from cyclohexanone (RO) to AA using cleaner oxidant such as O2 or H2O2 is proposed [4]. It is reported that the yields of AA in this oxidation process are comparable to those obtained in the currently commercial practice. In this process, usually acetic acid (HOAc) is used as the solvent, and adipic acid and water are the major products. Due to the existence of water, the reaction mixture would split into two liquid phases, i.e., an upper cyclohexanone-rich phase essentially containing the unconverted cyclohexanone, and a lower water-rich phase essentially containing HOAc, AA, water and by-products such as glutaric acid and succinic acid.

Thus, it is essential to obtain the liquid–liquid equilibrium data (LLE) for the ternary system water + acetic acid + cyclohexanone, which is important for the control, simulation, design, and optimization of the related oxidation and separation operations. However, except for the work of Ratkovics [5], no publication or reports on this system are available. Furthermore, in the work of Ratkovics [5], the LLE data for the ternary system water + cyclohexanone + acetic acid were only measured at 293.15 K and 101.3 kPa, and the experimental results were difficult to extrapolate to other temperatures.

The objective of this work is to experimentally determine the LLE data for the ternary system water + acetic acid + cyclohexanone. The experiments were carried out at T = (293.2–323.2) K and atmospheric pressure. To check the reliability of the measured data, comparisons between the experimental data with the literature data from Ratkovics [5] of the ternary system at 293.5 K were made. Moreover, the consistency of the experimental tie-line data was ascertained by applying the Othmer–Tobias and Bachman equations [6], [7]. NRTL [8] and UNIQUAC [9] models were used to correlate the experimental results, and the binary interaction parameters were obtained.

Section snippets

Materials

Materials such as acetic acid, water, cyclohexanone, N,N-dimethylformamide and chlorobenzene were obtained from Aladdin Chemistry Co. They all have the declared purities of >0.990 in mass. Purified water manufactured by Hangzhou Wahaha Group Co. was obtained from the supermarket (596 ml each bottle). In this work, the purities of acetic acid and cyclohexanone were checked by gas chromatography (GC), and the purity of water was verified by Karl Fischer titrator. All the chemicals were used

Experimental results

The measured LLE data of the ternary system water (1) +acetic acid, (2) +cyclohexanone, (3) at (293.2, 303.2, 313.2 and 323.2) K are given in Table 2, where wi1 and wi3 denotes the mass fraction of the ith component in the aqueous phase and organic phase, respectively. The experimental data of the ternary system at different temperatures are plotted in Fig. 1. All concentrations are listed in mass fraction.

The experimental results show that the mutual solubility of water and cyclohexanone

Conclusions

Liquid–liquid equilibriua (LLE) for the ternary system water + acetic acid + cyclohexanone was studied at (293.2–323.2) K and at atmospheric pressure. In the studied temperature range, the immiscibility region was found to be relatively small and not sensitive to the change of temperature. The Othmer–Tobias equation and the Bachman equation were both used to check the reliability of the obtained experimental tie-line data. The experimental results were correlated with both the NRTL and the UNIQUAC

Acknowledgements

The project was granted financial support from Key S&T Special Project of Zhejiang Province (2012C13007-2) and the Fundamental Research Funds for the Central Universities.

References (14)

  • S.A. Chavan et al.

    J. Catal.

    (2002)
  • F. Ratkovics et al.

    J. Chem.Thermodyn.

    (1991)
  • A. Castellan et al.

    Catal. Today

    (1991)
  • Y. Yuan et al.

    Org. Process Res. Dev.

    (2004)
  • R.E. Dickinson et al.

    Nature

    (1986)
  • D.F. Othmer et al.

    Ind. Eng. Chem.

    (1942)
  • I. Bachman

    Ind. Eng. Chem.

    (1940)
There are more references available in the full text version of this article.

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