Elsevier

Fluid Phase Equilibria

Volume 352, 25 August 2013, Pages 97-99
Fluid Phase Equilibria

Vapor-liquid equilibria of binary mixtures of propylene oxide with either ethyl benzene, 2-methylpentane, or 2-methyl-1-pentene

https://doi.org/10.1016/j.fluid.2013.04.008Get rights and content

Highlights

  • The solubility of propylene oxide in ethyl benzene is measured.

  • The solubility of propylene oxide in 2-methylpentane is measured.

  • The solubility of propylene oxide in 2-methyl-1-pentene is measured.

  • Data cover a temperature range of 323–373 K and pressures up to 5 bar.

  • Propylene oxide solubility is highest in ethyl benzene.

Abstract

In this experimental investigation, the bubble points of three binary mixtures consisting of propylene oxide + ethyl benzene, propylene oxide + 2-methylpentane, and propylene oxide + 2-methyl-1-pentene were determined. The method of experimentation was the synthetic method in which phase change for a mixture of constant overall composition is observed visually by varying pressure at constant temperature. Each binary system was measured for a range of concentrations. Temperatures and pressures also varied from 323 K to 373 K and up to 5 bar, respectively. It is observed that the solubility of propylene oxide varies, in increasing order, in 2-methylpentane, 2-methyl-1-pentene, and ethyl benzene, with the solubility being far greater in ethyl benzene compared to either 2-methylpentane or 2-methyl-1-pentene.

Introduction

Propylene oxide, also known as PO, 1,2-epoxypropane, propene oxide, methyl ethylene oxide, methyloxirane, propylene epoxide, and epoxypropane, is primarily used as an intermediate in the synthesis of other chemicals and polymers. Accurate data on the phase equilibria of mixtures with propylene oxide are necessary for proper design and optimization of the relevant chemical processes and purification steps. In this respect, binary mixtures of propylene oxide with hydrocarbons can be of significance. For example, one of the techniques to produce styrene monomer, and propylene oxide as byproduct, includes the oxidation of ethyl benzene to ethyl benzene hydroperoxide, and then epoxidizing propylene with hydroperoxide to produce the epoxide and an alcohol. The alcohol, either tert-butanol or 1-phenylethanol, is further processed to produce co-products such as methyl-tert-butylether and stryrene. The propylene oxide that is separated from the epoxidation reactor effluent is purified by a series of conventional and extractive distillations in order to reduce the content of aldehydes, ethyl benzene, water, and acetone [1], [2]. Another example includes a propylene oxide purification procedure involving n-heptane as extracting agent, to purify a mixed stream of propylene oxide, 2-methylpentane, methanol, water, and acetaldehyde as impurities [3]. Knowledge of the phase behaviour of the components involved in such processes, including the solubility of propylene oxide in ethyl benzene in the first example, or methylpentane in the second example, within a range of temperatures and pressures is useful for the optimal design, operation and maintenance of such processes. In this experimental study, we measure the solubility of propylene oxide in three different hydrocarbons, namely, ethyl benzene, 2-methylpentane, or 2-methyl-1-pentene.

Section snippets

Experimental

The experiments are conducted in the Cailletet apparatus. This high-pressure equipment measures multiphase equilibria according to the visual synthetic method. In the case of bubble point measurements, a mixture of fixed overall composition is sealed within a Pyrex equilibrium tube, the temperature is fixed at a steady value, the pressure is lowered until both vapour and liquid phases prevail, and then the pressure is gradually increased until the last bubble of vapour disappears while the

Results

The measured bubble points for the different mixtures of constant overall composition of propylene oxide with ethyl benzene, 2-methylpropane, and 2-methyl-1-propene are presented in Table 1, Table 2, Table 3, respectively. Each binary system is measured within the temperature range of 323–373 K. The measured bubble points indicate the solubility limit of propylene oxide in the three hydrocarbons. The pressure-temperature behaviour of the different isopleths is shown for the three binary systems

Acknowledgement

Sona Raeissi is thankful to Shiraz University and Delft University of Technology for facilitating this collaboration.

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Cited by (2)

  • Design and optimization of an integrated process for the purification of propylene oxide and the separation of propylene glycol by-product

    2022, Chinese Journal of Chemical Engineering
    Citation Excerpt :

    To obtain the reasonable interaction parameters, the NRTL model [27] is selected to describe the phase equilibrium data from experimental measurement. Meanwhile, some binary parameters for certain systems built in Aspen Plus software are modified according to experimental results [4,28–34]. However, no related phase equilibrium data for the mixtures of PO + DPG and ethyl benzene (EB) + 2-MET are available in open literatures so far.

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