Elsevier

Fluid Phase Equilibria

Volume 307, Issue 2, 25 August 2011, Pages 180-184
Fluid Phase Equilibria

Isobaric vapor–liquid equilibrium for binary systems containing benzothiophene

https://doi.org/10.1016/j.fluid.2011.04.024Get rights and content

Abstract

Isobaric vapor–liquid equilibrium (VLE) of the following systems was measured with a recirculation still: benzothiophene + dodecane at 99.6 kPa, benzothiophene + 1-dodecene at 100.1 kPa, and benzothiophene + 1-octanol at 100 kPa. All systems studied exhibit positive deviation from Raoult's law. A minimum temperature azeotrope was found in the systems benzothiophene + dodecane (x1 = 0.491, P = 99.6 kPa, T = 484.72 K) and benzothiophene + 1-dodecene (x1 = 0.185, P = 100.1 kPa, T = 484.45 K). No azeotropic behavior was found in benzothiophene + 1-octanol system at 100 kPa. The experimental results were correlated with the Wilson model and compared to COSMO-SAC predictive model. Liquid and vapor phase compositions were determined with gas chromatography. All measured data sets passed the thermodynamic consistency tests. The activity coefficients at infinite dilution are also presented.

Highlights

► Three isobaric VLE for systems containing benzothiophene were measured. ► Systems benzothiophene + dodecane and benzothiophene + 1-dodecene show azeotropic behavior. ► The experimental results were correlated with the Wilson model. ► All measured data sets passed the thermodynamic consistency tests.

Introduction

Benzothiophene is found as one of the organic sulfur compounds present in Fluid Catalytic Cracking (FCC) products [1], [2]. The organic sulfur compounds should be removed to meet the standards of environmental legislation and ultra-low-sulfur fuel is required in many countries [3].

As a continuation of our sulfur component measurement project, in this work we have measured isobaric VLE for systems benzothiophene + dodecane at 99.6 kPa, benzothiophene + 1-dodecene at 100.1 kPa, and benzothiophene + 1-octanol at 100 kPa with a recirculation still. No other VLE of the binaries studied in this work has been found in the literature search.

Section snippets

Materials

Benzothiophene, dodecane, 1-dodecene, 1-octanol, were provided by Sigma–Aldrich, Finland. Benzothiophene was melted before used. The purity of all substances was checked by gas chromatography (GC) equipped with a flame ionization detector (FID). All chemicals were dried over molecular sieves (Merck 3 Å) for 24 h. The refractive indexes, nD, of the pure liquids were measured at 298.15 K with ABBEMAT-HP automatic refractometer (Dr. Kernchen, Germany) with accuracy ±0.00002. The purity and measured

Vapor pressure measurements

The vapor pressures of benzothiophene, dodecane, 1-dodecene, and 1-octanol measured in this work are shown in Fig. 1 and presented in Table 3. The Antoine parameters for were regressed from the vapor pressures measured in this work. These parameters with the recommended temperature range of the vapor pressure equations are presented in Table 2 including the absolute average deviation of pressure (|ΔPaverS|) between measured (Pi,exp) and values calculated with regressed parameters of the Antoine

Conclusions

Vapor pressures of benzothiophene, dodecane, 1-dodecene, and 1-octanol were measured and compared with the literature data. The agreement between vapor pressures measured in this work and found in the literature was good. Isobaric VLE data for the systems benzothiophene + dodecane at 99.6 kPa, benzothiophene + 1-dodecene at 100.1 kPa, and benzothiophene + 1-octanol at 100 kPa were measured with a recirculation still. All systems studied exhibit positive deviation from Raoult's law. A minimum temperature

Acknowledgement

The authors acknowledge Academy of Finland for the financial support.

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    Using these parameters, in Fig. 4, the predicted phase behavior for thiophene + hexane at constant temperatures of 338.15 K and 323.15 K is presented (Fig. 4a) and excellent agreement is obtained with experimental results. The system thiophene + n-hexane shows positive deviations from Raoult's law and maximum pressure azeotropy [25], due to the close nature of the thiophene (Tb = 357.31 K) and n-hexane (Tb = 341.88 K) boiling points; the closer the boiling points of the pure components and the less ideal the mixture, the greater the likelihood of an azeotrope. If hexane is changed to hexene, which involves only the change of a single group within the model, the theoretical predictions are again found to be in good agreement with the experimental results as shown in Fig. 4b, with the theory correctly predicting no azeotropic behavior.

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