Phase equilibria on five binary systems containing 1-butanethiol and 3-methylthiophene in hydrocarbons
Introduction
Stringent air quality regulations impose the use of ultra-low sulfur gasoline and diesel in many countries [1]. In Europe, the sulfur level in gasoline and diesel should be lower than 10 ppm beginning from 2009 [2]. New developments on sulfur separation process design to further decrease the sulfur level have become one of the major challenges to the refining industry [3]. Design of separation processes to accomplish the removal of sulfur compounds requires the knowledge of the behavior of sulfur compounds in hydrocarbons. Information of such systems is scarce and experimental work is required. 1-Butanethiol and 3-methylthiophene are typical organic sulfur compounds present in the hydrocarbon streams originating from the fluid catalytic cracker (FCC) [4], [5].
In this work, we measured vapor–liquid equilibrium (VLE) for the systems 1-butanethiol + methylcyclopentane at 343.15 K, 1-butanethiol + 2,2,4-trimethylpentane at 368.15 K, 3-methylthiophene + toluene at 383.15 K, 3-methylthiophene + o-xylene at 383.15 K, and 3-methylthiophene + 1,2,4-trimethylbenzene at 383.15 K with a recirculation still. No other VLE data of the binary systems studied in this work have been found in the literature search.
In the previous studies, Sapei et al. [6], [7] measured VLE data for the systems 3-methylthiophene + 2,2,4-trimethylpentane at 368.15 K, 3-methylthiophene + 2,4,4-trimethyl-1-pentene at 368.15 K, 3-methylthiophene + cyclohexane at 348.15 K, 3-methylthiophene + 1-hexene at 333.15 K, 3-methylthiophene + 2-methylpentane at 333.15 K, 3-methylthiophene + n-hexane at 333.15 K, 3-methylthiophene + methylcyclopentane at 343.15 K, and 3-methylthiophene + methylcyclohexane at 373.15 K. Kilner et al. [8] measured vapor–liquid equilibrium for system 1-butanethiol + n-hexane and 1-butanethiol + toluene for mole fractions x = 0–0.2 of 1-butanethiol at temperatures between 323 and 373 K.
Section snippets
Materials
1-Butanethiol, 3-methylthiophene, methylcyclopentane, 2,2,4-trimethylpentane, toluene, o-xylene, and 1,2,4-trimethylbenzene were provided by Sigma–Aldrich, Finland. 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 3Å) 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
Vapor pressure measurements
Vapor pressure of 3-methylthiophene, methylcyclopentane, 2,2,4-trimethylpentane, toluene, and o-xylene were measured in the previous studies [6], [7], [13], [14], [15]. The Antoine parameters for 1-butanethiol and 1,2,4-trimethylbenzene 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 3. The average absolute deviation of pressure () between measured () and
Conclusions
Vapor pressures of 1-butanethiol and 1,2,4-trimethylbenzene were measured and compared with the literature data. The agreement between vapor pressures measured in this work and found in the literature was good. Isothermal VLE data for the systems 1-butanethiol + methylcyclopentane at 343.15 K, 1-butanethiol + 2,2,4-trimethylpentane at 368.15 K, 3-methylthiophene + toluene at 383.15 K, 3-methylthiophene + o-xylene at 383.15 K, and 3-methylthiophene + 1,2,4-trimethylbenzene at 383.15 K with a recirculation
Acknowledgements
The authors acknowledge Neste Jacobs Oy and Neste Oil Oyj for the financial support.
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