Article pubs.acs.org/jced
Vapor−Liquid Equilibrium for Methoxymethane + Thiophene, + Diethylsulfide, + 2‑Methyl-2-propanethiol and 1‑Hexene, + 1‑Propanethiol Petri Uusi-Kyyny,*,† Erlin Sapei,† Juha-Pekka Pokki,† Minna Pakkanen,† Kari I. Keskinen,†,‡ and Ville Alopaeus† †
School of Chemical Technology, Research Group of Chemical Engineering, Aalto University, P.O. Box 16100 FI-00076 Aalto, Finland ‡ Neste Jacobs Oy, P.O., Box 310, FI-06101 Porvoo, Finland ABSTRACT: The isothermal vapor−liquid equilibrium (VLE) of binary systems of methoxymethane (dimethylether, DME) + thiophene, DME + 2-methylpropane-2-thiol, and DME + diethylsulfide was measured with a static total pressure apparatus. Barker’s method was used to obtain phase equilibrium data from the total pressure measurements. Additionally 5 VLE data points of the binary system of 1-hexene + 1-propanethiol were measured with a glass recirculation still. The system reacted partly during the VLE measurements to form a sulfide at thiol mole fractions higher than x(1-propanethiol) = 0.1. The formation of the sulfide was verified by gas chromatographic analysis. The measured nonreacted points at low thiol concentration showed that the system 1-hexene + 1-propanethiol exhibited azeotropic behavior.
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the so-called thiol−ene reaction.4 Several equilibrium points were measured with the recirculation still for the 1-hexene +1-propanethiol system in a composition, temperature, and pressure range where reactions did not occur.
INTRODUCTION DME is used as a substitute for liquefied petroleum gas (LPG) in China. The use of DME as LPG blending stock is also considered in other countries like South Korea and Indonesia. In the residential cooking and heating sectors DME can be blended up to 20 vol % into LPG without any change of sealing materials.1 Other uses or proposed uses include it as a propellant for health care products, transportation fuel and small scale electric power generation. DME is one of the chemicals, of which the production has increased significantly in recent years. Current annual production is approximately 10 million metric tons, which includes the market use of 3 million metric tons.1 To detect LPG in the case of leaks, it is marked with compounds which in small quantities can be detected organoleptically with ease.2 These LPG odorants come into contact with DME during the process of blending DME into LPG. The modeling of the behavior of these systems requires VLE data. In this work isothermal VLE data for DME + thiophene, DME + 2-methylpropane-2-thiol, and DME + diethylsulfide were measured with a static total pressure method. These measurements can also be used in the development of phase equilibria estimation methods. One interesting feature of available VLE measurements for organic sulfur component containing systems is the absence of alkene + thiol measurements. A measurement for only one system ethanethiol + propene3 at two temperatures was found in the literature. The reason is not only the repulsive smell of thiols but also the reactivity of alkenes with thiols to form sulfides, © 2013 American Chemical Society
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EXPERIMENTAL SECTION Materials. The sample description table with suppliers and the purities of the materials used are presented in Table 1. DME was used as such. The thiophene, 2-methylpropane-2-thiol, diethylsulfide, 1-hexene, and 1-propanethiol were analyzed with a GC, equipped with a flame ionization detector. Molecular sieves (Merck, 3A, dried in an oven at 573 K) were used to dry the liquid components. Additional verification of the materials purity was obtained from the comparison of measured vapor pressures against literature correlations and the refractive indexes of pure components at 298.15 K (Abbemat-HP automatic refractometer, manufactured by Dr. Kernchen, Germany). DME was excluded from the refractive index measurement due to its high vapor pressure at 298.15 K. Excellent correspondence between measured and literature values were obtained.5,6 Degassing is of utmost importance for accurate and successful static total pressure measurements. Degassing with vacuum suction and simultaneous application of ultrasound to the pure
Received: November 28, 2012 Accepted: February 26, 2013 Published: March 8, 2013 956
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Journal of Chemical & Engineering Data
Article
Table 1. Supplier and the Purity of the Compoundsa compound
company
GC purity mass fraction
nD(298 K) measured
nD(298 K) literature
DME thiophene 2-methylpropane-2thiol diethylsulfide 1-hexene 1-propanethiol
Linde Gas Merck Sigma-Aldrich
0.999b 0.999 0.998
na 1.52869 1.42000
na 1.52572c 1.42004c
Sigma-Aldrich Sigma-Aldrich Sigma-Aldrich
0.997 0.999 0.999
1.43998 1.3851 1.4353
1.44015c 1.38502d 1.43533d
vapor pressure was separately measured in the course of the VLE measurements. The gaseous component degassing was achieved by sequential opening and closing of the vacuum valve 10 times for a period of 5 s. Apparatus. Static Total Pressure Apparatus. The static total pressure apparatus used in the measurement has been described by Uusi-Kyyny et al.10 A temperature meter equipped with calibrated Pt-100 probes was used (Termolyzer S2541, Frontek). The total pressure of the mixture and the pure component vapor pressures were measured with a Digiquartz 2300A-101-CE pressure transducer (0 kPa to 2070 kPa), with a compensated temperature range from (219 K to 380 K) connected to a Digiquartz 740 intelligent display unit (Paroscientific). The volume of the equilibrium cell was 113.36 ± 0.02 cm3. The compounds were metered into the equilibrium cell with syringe pumps (ISCO 260D and 100D). Circulation Still. A Yerazunis-type of a circulation still11,12 was used for the 1-propanethiol + 1-hexene measurements. The total volume of liquid in the equipment needed for reliable operation was approximately 80 cm3. The thermometer (F200, Tempcontrol) used for the measurement of equilibrium temperature was equipped with Pt-100 probes. The manufacturer’s stated accuracy was ± 0.02 K, additionally the calibration uncertainty was ± 0.01 K. The total uncertainty was estimated as ± 0.05 K for the temperature measurement. The pressure measurement uncertainty was estimated as ± 0.17 kPa including the transducer (Druck PMP 4070 from (0 kPa to 100 kPa)) uncertainty, panel meter (Red Lion) uncertainty, and the calibration uncertainty (calibrator BEAMEX PC 1051166). Procedure. Static Total Pressure Measurements. The pure component vapor pressure was the first point measured with the degassed components. The vapor pressure value was compared against literature correlation. A favorable result in the vapor pressure comparison was prerequisite for the reliable measurement of the mixture total pressures. For vapor pressure and mixture points equilibrium was considered to be reached in less than 0.5 h and the addition of a predefined amount of the second compound could commence. The additions were repeated until the composition was approximately equimolar. After reaching equimolar composition the cell was emptied and the cell was dried by applying reduced pressure. The other half of the isotherm was measured in a similar fashion beginning from the pure component vapor pressure.
a
Refractive index, nD, u(nD) = 0.00002, at 298.15 K, u(T) = 0.03 K. Purity according to manufacturer. cReference 5. dReference 6; na, not available.
b
liquid component placed in a round-bottom flask was used in this work. The component to be degassed was cooled by keeping ice in the ultrasonic baths water container. Cooling of the liquid component reduced the total amount of liquid needed for initiating measurements in the degassing phase. Additionally the formation of smelly organic sulfur compound waste to be disposed of was minimized with this method. The degassing setup has been presented in an earlier publication.7 Vapor pressures of the pure components and literature correlations5,8,9 are shown in Table 2. Each value of the pure component Table 2. Pure Compound Vapor Pressures, Experimental pmeas and Computed from Literature Correlation pcorrelation at Temperature Ta pcorrelation/kPa compound
T/K
pmeas/kPa
ref 6
ref 8b
ref 9
DME DME DME DME thiophene thiophene 2-methylpropane-2thiol diethylsulfide 1-hexene 1-hexene 1-hexene
308.14 335.63 336.70 336.63 308.14 335.63 336.69
786.6 1540.0 1572.2 1572.2 16.9 49.4 98.5
782.4 1545.5 1583.3 1580.8 16.6 49.4 99.3
773.1 1512.9 1549.5 1547.1 16.7 49.4 na
783.0 1536.4 1573.6 1571.1 16.6 49.4 94.7
336.63 328.15 336.09 335.74
39.7 77.0 99.8 98.7
39.3 76.9 99.7 98.6
39.4 76.8 99.5 98.4
39.4 76.8 99.6 98.5
a
u(T) = 0.03 K, u(pmeas) = 0.4 kPa for DME, thiophene, 2-methylpropanethiol, and diethylsulfide, u(pmeas) = 0.15 kPa for 1-hexene; vapor pressure from literature correlation, pcorrelation. bAbbreviations: na, not available.
Table 3. Physical Properties of Pure Compoundsa compound
DME
thiophene
2-methylpropane-2-thiol
diethylsulfide
1-hexene
1-propanethiol
CAS TC/K pC/MPa ω vi/(cm3·mol−1) A B C Tmin/K Tmax/K
115-10-6 400.1b 5.37b 0.200221b 70.2314b
110-02-1 579.35c 5.69c 0.196972c 79.4848c
75-66-1 530c 4.06c 0.191395c 113.524c
352-93-2 557.15c 3.96c 0.29002c 108.398c
592-41-6 504c 3.21c 0.285121c 125.8c 6.9000d 2655.0085d −47.6225d 298.99d 336.04d
107-03-9 536.6c 4.63c 0.231789c 91.1676c 7.0174e 2724.9699e −47.9846e 310.52e 375.24e
Chemical Abstracts Service registry number, CAS; critical temperature, TC; critical pressure, pC; acentric factor, ω; molar volume vi at 298 K; vapor pressure correlation (pS/MPa = exp(A − [B/(T/K + C])) parameters A through C, for the temperature range from Tmin to Tmax. bReference 5. c Reference 6. dReference 20. eReference 21. a
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± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0 0.0003 0.0004 0.0006 0.0010 0.0014 0.0018 0.0024 0.0030 0.0037 0.0045 0.00540 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0.0066 0 0.0003 0.0003 0.0003 0.0003 0.0003 0.0004 0.0004 0.0004 0.0005 0.0005 0.0006 0.0007 0.0007 0.0007 0.0007
n2/mol 0 0.0056 0.0173 0.0303 0.0646 0.1012 0.1434 0.1913 0.2455 0.3082 0.3807 0.4670 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0.5739 0 0.0057 0.0176 0.0299 0.0640 0.1018 0.1435 0.1911 0.2463 0.3086 0.3808 0.4674 0.5726 0.5726 0.5726 0.5726
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0051 0.0042 0.0035 0.0029 0.0023 0.0018 0.0014 0.0010 0.0006 0.0005 0.0004 0 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0062 0.0061 0.0051 0.0042 0.0034
n1/mol
0.5714 0.5714 0.5714 0.5714 0.5714 0.5714 0.5714 0.5714 0.5714 0.5714 0.5714 0.5714 0.5724 0.4700 0.3832 0.3107 0.2479 0.1943 0.1455 0.1039 0.0665 0.0324 0.0204 0.0076 0 0.5731 0.5731 0.5731 0.5731 0.5731 0.5731 0.5731 0.5731 0.5731 0.5731 0.5731 0.5731 0.5691 0.4654 0.3805 0.3066
T/K
335.63 335.63 335.63 335.63 335.63 335.63 335.63 335.63 335.63 335.63 335.63 335.63 335.64 335.63 335.63 335.64 335.63 335.64 335.64 335.64 335.64 335.64 335.64 335.64 335.63 308.14 308.14 308.14 308.14 308.14 308.13 308.13 308.14 308.14 308.14 308.14 308.14 308.13 308.14 308.13 308.14
1 0.990 0.971 0.950 0.898 0.850 0.799 0.749 0.699 0.650 0.600 0.550 0.499 0.450 0.400 0.351 0.302 0.253 0.202 0.153 0.104 0.053 0.034 0.013 0 1 0.990 0.970 0.950 0.900 0.849 0.800 0.751 0.700 0.650 0.601 0.552 0.499 0.448 0.399 0.349
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
z1 0 0.001 0.001 0.001 0.002 0.003 0.004 0.004 0.005 0.005 0.005 0.006 0.006 0.006 0.005 0.005 0.005 0.004 0.004 0.003 0.002 0.002 0.001 0.001 0 0 0.001 0.001 0.001 0.002 0.002 0.002 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003 0.003
1540.0 1519.8 1481.1 1442.2 1350.9 1270.3 1191.6 1116.1 1043.8 972.9 904.4 836.7 766.0 690.8 616.4 544.4 472.4 402.8 330.7 261.8 192.9 123.3 97.1 67.6 49.4 786.6 776.8 759.7 742.5 699.6 658.7 620.0 582.4 545.1 509.2 474.1 439.6 403.6 361.8 322.2 282.3
pmeas/kPa 1540.0 1520.1 1481.2 1441.7 1350.5 1270.0 1191.6 1116.6 1044.5 973.6 904.2 834.7 763.7 690.8 617.2 545.2 473.0 402.8 330.7 261.8 193.0 123.5 97.1 67.5 49.4 786.6 777.4 759.7 742.2 699.0 658.3 620.0 582.7 545.6 509.8 474.1 437.7 399.2 360.4 322.2 282.8
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.4 1.4 1.7 2.0 2.1 1.8 1.4 0.9 1.1 1.2 1.4 1.6 1.6 1.4 1.2 0.9 1.0 0.8 0.6 0.6 0.8 0.6 0.6 0.9 0.4 0.4 0.8 1.0 1.1 1.2 1.1 0.9 0.7 0.8 0.9 0.9 0.9 0.8 0.6 0.4 0.5
pLeg/kPa 1 0.989 0.968 0.946 0.892 0.842 0.791 0.741 0.692 0.643 0.595 0.546 0.497 0.446 0.395 0.345 0.295 0.246 0.196 0.148 0.099 0.051 0.033 0.012 0 1 0.990 0.969 0.949 0.897 0.846 0.796 0.746 0.696 0.647 0.598 0.549 0.497 0.447 0.397 0.346
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
x1 0 0.001 0.001 0.002 0.003 0.003 0.004 0.005 0.005 0.005 0.006 0.006 0.006 0.006 0.005 0.005 0.005 0.004 0.004 0.003 0.002 0.002 0.001 0.001 0 0 0.0006 0.0008 0.001 0.0015 0.0019 0.0023 0.0025 0.0028 0.0029 0.003 0.0031 0.003 0.003 0.003 0.0029
1 0.999 0.998 0.996 0.993 0.989 0.986 0.982 0.978 0.974 0.970 0.964 0.958 0.951 0.942 0.930 0.916 0.897 0.869 0.828 0.759 0.612 0.501 0.274 0 1 0.9996 0.9989 0.9981 0.9962 0.9942 0.9921 0.9900 0.9876 0.9851 0.9823 0.9790 0.9749 0.9701 0.9642 0.9566
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
y1 0 0.000 0.000 0.000 0.000 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.002 0.002 0.002 0.002 0.002 0.003 0.004 0.008 0 0 0 0.0001 0.0001 0.0002 0.0003 0.0004 0.0004 0.0005 0.0005 0.0006 0.0007 0.0008 0.0009 0.0011 0.0013
1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.001 ± 0.000 1.005 ± 0.002 1.010 ± 0.003 1.017 ± 0.004 1.026 ± 0.006 1.035 ± 0.008 1.05 ± 0.01 1.06 ± 0.01 1.07 ± 0.01 1.08 ± 0.01 1.09 ± 0.01 1.10 ± 0.01 1.11 ± 0.02 1.12 ± 0.02 1.13 ± 0.02 1.14 ± 0.02 1.15 ± 0.02 1.17 ± 0.03 1.19 ± 0.04 1.20 ± 0.04 1.21 ± 0.04 1.22 ± 0.05 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.00 ± 0.00 1.01 ± 0.00 1.01 ± 0.00 1.02 ± 0.00 1.03 ± 0.00 1.04 ± 0.01 1.05 ± 0.01 1.06 ± 0.01 1.07 ± 0.01 1.07 ± 0.01 1.08 ± 0.01 1.09 ± 0.01
γ1
1.35 ± 0.08 1.34 ± 0.07 1.32 ± 0.07 1.29 ± 0.06 1.24 ± 0.04 1.19 ± 0.03 1.16 ± 0.02 1.13 ± 0.02 1.10 ± 0.01 1.08 ± 0.01 1.064 ± 0.006 1.050 ± 0.005 1.039 ± 0.005 1.030 ± 0.004 1.023 ± 0.004 1.017 ± 0.003 1.013 ± 0.003 1.009 ± 0.002 1.006 ± 0.002 1.004 ± 0.001 1.002 ± 0.001 1.001 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.26 ± 0.04 1.25 ± 0.04 1.24 ± 0.04 1.23 ± 0.03 1.20 ± 0.02 1.16 ± 0.02 1.13 ± 0.01 1.11 ± 0.01 1.08 ± 0.01 1.06 ± 0.01 1.05 ± 0.00 1.04 ± 0.00 1.03 ± 0.00 1.02 ± 0.00 1.01 ± 0.00 1.01 ± 0.00
γ2
Table 4. (Vapor + Liquid) Equilibrium Data for Temperature T, Amount of Substances in Equilibrium Cell n1 and n2, Total Composition z1, Measured Pressure pmeas and Pressure Obtained from the Legendre Model pLeg, Liquid-Phase Mole Fraction x, Vapor-Phase Mole Fraction y, and Liquid Activity Coefficient γ, for the System DME (1) + Thiophene (2)a
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0.01 0.01 0.01 0.01 0.02 0.02 0.03 0.03 0.03
1.01 ± 0.00 1.01 ± 0.00 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000
The data were considered acceptable if the pure component vapor pressures were in line with literature values and the total pressures coincided at the mole fraction of 0.5. Circulation Still Measurements. Vapor pressure of component 1 was measured at several temperatures. Component 2 was added into the apparatus. The measurement procedure for one VLE point, from addition to sampling, took approximately from 25 to 30 min. The system was considered to be in steady state when the temperature was steady. This short time to reach equilibrium is possible only in the dilute range of composition. After reaching steady state of operation and the temperature and the pressure were recorded, the equilibrium samples were withdrawn (approximately 0.25 cm3). Approximately 1 cm3 of cooled o-xylene was added prior to sampling to the cooled 2 cm3 vial as a diluent. Both samples were analyzed by gas chromatography (GC) as soon as possible. The GC used for analyzing the samples was located in a separately ventilated enclosure, due to the odor of the liquid components used in this work. A gas chromatograph (Agilent 6850A) with an autosampler and a flame ionization detector (FID) was used. The common HP-1 dimethylpolysiloxane (60.0 m × 250 μm × 1.0 μm) column was used to separate the components and the diluent. Before the GC was calibrated with gravimetrically prepared samples (10 mixtures), pure components retention times were determined. The volume of the sample was reduced by adding the diluent. The response factor F2 of component 2 was determined with eq 1.
y1
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 244.3 204.8 167.7 130.9 94.9 60.8 47.1 31.2 16.9
± ± ± ± ± ± ± ± ±
0.6 0.6 0.5 0.5 0.6 0.5 0.4 0.6 0.4
m2 A1 = F2 m1 A 2
243.9 204.8 167.7 130.9 94.7 60.8 47.1 31.2 16.9 ± ± ± ± ± ± ± ± ±
A1 m1 A1 m1
( ) A
+ F2 m2
(2)
2
where M1 and M2 are the molar mass of components 1 and 2. The maximum error of liquid and vapor composition measurements is estimated to be 0.001-mol fraction in the composition range of the measurements of this work.
0.0007 0.0007 0.0007 0.0007 0.0007 0.0007 0.0007 0.0007 0.0007
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DATA REDUCTION Thermodynamic Model. The equation for the calculation of the activity coefficients γi is presented:
± ± ± ± ± ± ± ± ±
u(T) = 0.03 K, u(pmeas) = 0.4 kPa.
γi =
yp ϕ i i xipiS ϕiS
exp
∫p
piS
ViL dp RT
(3)
where yi is the mole fraction of component i in the vapor phase; p is the total pressure of the system; ϕi is the vapor phase fugacity coefficient of component i; xi is the liquid phase mole fraction of the component i; pSi is the vapor pressure of pure component i at the system temperature; ϕSi is the pure component-saturated liquid fugacity coefficient at the system temperature T; VLi is the molar volume of pure component i in liquid phase at the system temperature T; T is the temperature in Kelvin; R is the universal gas constant (8.31441 J·K−1·mol−1).
a
n2/mol
0.299 0.249 0.200 0.152 0.104 0.058 0.040 0.019 0
z1
x1 =
0.5726 0.5726 0.5726 0.5726 0.5726 0.5726 0.5726 0.5726 0.5726 ± ± ± ± ± ± ± ± ±
0.0028 0.0022 0.0018 0.0013 0.0010 0.0007 0.0005 0.0004 0
n1/mol
0.2447 0.1893 0.1433 0.1023 0.0662 0.0353 0.0238 0.0109 0
T/K
308.14 308.14 308.13 308.14 308.14 308.14 308.14 308.14 308.14
Table 4. continued
(1)
A1 and A2 were the GC peak areas in a sample of components 1 and 2. The area of the diluent is left out from the integration; m1 and m2 were masses in the gravimetrically prepared sample of components 1 and 2, respectively. The composition of component 1 in the binary mixture can thus be determined with
0.003 0.002 0.002 0.002 0.002 0.001 0.001 0.001 0
pmeas/kPa
pLeg/kPa
0.296 0.245 0.197 0.149 0.101 0.057 0.039 0.0182 0
0.0027 0.0025 0.0022 0.0019 0.0015 0.0011 0.0009 0.0007 0
0.9468 0.9330 0.9142 0.8852 0.8351 0.7334 0.6515 0.4652 0 x1
0.0015 0.0019 0.0022 0.0027 0.0034 0.0047 0.006 0.0095 0
1.09 1.10 1.10 1.11 1.12 1.14 1.15 1.16 1.17
γ1
Article
± ± ± ± ± ± ± ± ±
γ2
Journal of Chemical & Engineering Data
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a
960
0±0 0.0037 ± 0.0002 0.0129 ± 0.0003 0.0217 ± 0.0003 0.0458 ± 0.0004 0.0728 ± 0.0005 0.1042 ± 0.0007 0.1381 ± 0.0008 0.1768 ± 0.0010 0.2230 ± 0.0012 0.2757 ± 0.0015 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021 0.4126 ± 0.0021
u(T) = 0.03 K, u(pmeas) = 0.4 kPa.
n2/mol
n1/mol
0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4077 ± 0.0045 0.4117 ± 0.0045 0.3369 ± 0.0036 0.2767 ± 0.0030 0.2244 ± 0.0024 0.1800 ± 0.0020 0.1413 ± 0.0016 0.1080 ± 0.0012 0.0773 ± 0.0009 0.0522 ± 0.0007 0.0289 ± 0.0004 0.0180 ± 0.0003 0.0095 ± 0.0002 0±0
T/K
336.70 336.70 336.70 336.70 336.71 336.70 336.69 336.69 336.70 336.70 336.70 336.70 336.70 336.70 336.69 336.70 336.70 336.70 336.70 336.70 336.70 336.69 336.69 336.69
1±0 0.991 ± 0.001 0.969 ± 0.001 0.949 ± 0.001 0.899 ± 0.002 0.848 ± 0.002 0.796 ± 0.003 0.747 ± 0.003 0.698 ± 0.004 0.646 ± 0.004 0.597 ± 0.004 0.499 ± 0.004 0.450 ± 0.004 0.401 ± 0.004 0.352 ± 0.004 0.304 ± 0.003 0.255 ± 0.003 0.207 ± 0.003 0.158 ± 0.002 0.112 ± 0.002 0.066 ± 0.001 0.042 ± 0.001 0.022 ± 0.001 0±0
z1 1572.2 1555.7 1516.5 1480.7 1395.5 1313.5 1232.4 1157.6 1085.5 1012.3 942.8 803.6 727.3 654.9 582.1 511.5 442.1 375.1 306.7 244.7 183.4 152.5 127.2 98.5
pmeas/kPa 1572.2 ± 0.4 1554.7 ± 1.2 1514.1 ± 1.3 1478.1 ± 1.3 1393.2 ± 1.0 1312.4 ± 0.6 1232.4 ± 0.4 1158.5 ± 0.5 1086.4 ± 0.5 1012.3 ± 0.4 940.9 ± 0.5 802.6 ± 0.5 727.0 ± 0.5 655.0 ± 0.5 582.2 ± 0.4 511.7 ± 0.4 442.0 ± 0.4 375.1 ± 0.4 306.7 ± 0.4 245.2 ± 0.4 183.4 ± 0.4 152.3 ± 0.5 127.4 ± 0.6 98.5 ± 0.4
pLeg/kPa 1±0 0.990 ± 0.001 0.966 ± 0.001 0.944 ± 0.001 0.890 ± 0.002 0.838 ± 0.003 0.785 ± 0.003 0.735 ± 0.004 0.687 ± 0.004 0.637 ± 0.004 0.589 ± 0.004 0.496 ± 0.004 0.445 ± 0.004 0.395 ± 0.004 0.345 ± 0.004 0.296 ± 0.003 0.248 ± 0.003 0.200 ± 0.003 0.151 ± 0.002 0.107 ± 0.002 0.062 ± 0.001 0.039 ± 0.001 0.021 ± 0.001 0±0
x1 1±0 0.999 ± 0.000 0.995 ± 0.000 0.992 ± 0.000 0.986 ± 0.001 0.979 ± 0.001 0.972 ± 0.001 0.965 ± 0.001 0.958 ± 0.001 0.950 ± 0.001 0.941 ± 0.001 0.921 ± 0.001 0.906 ± 0.001 0.890 ± 0.001 0.869 ± 0.001 0.844 ± 0.001 0.812 ± 0.002 0.769 ± 0.002 0.708 ± 0.002 0.623 ± 0.002 0.481 ± 0.002 0.367 ± 0.002 0.236 ± 0.002 0±0
y1 1.000 ± 0.000 1.000 ± 0.000 1.001 ± 0.000 1.003 ± 0.001 1.008 ± 0.001 1.016 ± 0.003 1.024 ± 0.003 1.032 ± 0.004 1.039 ± 0.005 1.046 ± 0.006 1.053 ± 0.006 1.065 ± 0.008 1.07 ± 0.009 1.08 ± 0.010 1.08 ± 0.011 1.09 ± 0.012 1.09 ± 0.013 1.10 ± 0.014 1.10 ± 0.015 1.11 ± 0.017 1.11 ± 0.019 1.11 ± 0.021 1.12 ± 0.022 1.12 ± 0.024
γ1
1.40 ± 0.062 1.37 ± 0.055 1.32 ± 0.043 1.28 ± 0.035 1.20 ± 0.022 1.14 ± 0.015 1.10 ± 0.011 1.08 ± 0.008 1.057 ± 0.007 1.043 ± 0.006 1.032 ± 0.005 1.019 ± 0.003 1.014 ± 0.003 1.010 ± 0.002 1.007 ± 0.002 1.005 ± 0.001 1.003 ± 0.001 1.002 ± 0.001 1.001 ± 0.000 1.001 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000
γ2
Table 5. (Vapor + Liquid) Equilibrium Data for Temperature T, Amount of Substances in Equilibrium Cell n1 and n2, Total Composition z1, Measured Pressure pmeas and Pressure Obtained from the Legendre Model pLeg, Liquid-Phase Mole Fraction x, Vapor-Phase Mole Fraction y, and Liquid Activity Coefficient γ, for the System DME (1) + 2Methylpropane-2-thiol (2)a
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a
961
0±0 0.0048 ± 0.0002 0.0134 ± 0.0002 0.0224 ± 0.0002 0.0468 ± 0.0002 0.0744 ± 0.0003 0.1048 ± 0.0003 0.1403 ± 0.0003 0.1792 ± 0.0004 0.2234 ± 0.0004 0.2768 ± 0.0005 0.3403 ± 0.0006 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007 0.4122 ± 0.0007
u(T) = 0.03 K, u(pmeas) = 0.4 kPa.
n2/mol
n1/mol
0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.4143 ± 0.0046 0.412 ± 0.0045 0.3361 ± 0.0037 0.2749 ± 0.0031 0.2223 ± 0.0026 0.1756 ± 0.0021 0.1368 ± 0.0017 0.104 ± 0.0014 0.0749 ± 0.0011 0.0481 ± 0.0008 0.0232 ± 0.0005 0.0142 ± 0.0004 0.0058 ± 0.0004 0±0
T/K
336.63 336.64 336.65 336.64 336.63 336.64 336.64 336.64 336.63 336.63 336.63 336.64 336.64 336.63 336.64 336.64 336.63 336.64 336.64 336.64 336.63 336.63 336.64 336.63 336.63
1±0 0.989 ± 0.001 0.969 ± 0.001 0.949 ± 0.001 0.899 ± 0.001 0.848 ± 0.002 0.798 ± 0.002 0.747 ± 0.003 0.698 ± 0.003 0.65 ± 0.003 0.600 ± 0.003 0.549 ± 0.003 0.500 ± 0.003 0.449 ± 0.003 0.400 ± 0.003 0.350 ± 0.003 0.299 ± 0.003 0.249 ± 0.003 0.201 ± 0.002 0.154 ± 0.002 0.104 ± 0.002 0.053 ± 0.001 0.033 ± 0.001 0.014 ± 0.001 0±0
z1 1572.2 1543.7 1502.7 1461.7 1366.6 1278.3 1197.5 1117.0 1043.4 972.8 900.7 830.0 759.1 681.1 607.0 533.2 457.2 385.7 317.8 250.7 181.8 112.0 84.8 58.8 39.7
pmeas/kPa 1572.2 ± 0.4 1546.6 ± 1.3 1504.8 ± 1.3 1463.3 ± 1.2 1367.0 ± 0.8 1278.1 ± 0.8 1196.8 ± 0.7 1117.0 ± 0.6 1043.5 ± 0.6 972.8 ± 0.6 900.6 ± 0.6 829.0 ± 0.6 758.8 ± 0.7 681.4 ± 0.7 607.5 ± 0.7 533.3 ± 0.6 457.2 ± 0.6 385.7 ± 0.7 317.6 ± 0.7 250.7 ± 0.4 182.2 ± 0.7 112.2 ± 0.7 84.8 ± 0.4 58.6 ± 0.9 39.7 ± 0.4
pLeg/kPa 1±0 0.987 ± 0.001 0.965 ± 0.001 0.943 ± 0.001 0.889 ± 0.002 0.837 ± 0.002 0.786 ± 0.003 0.735 ± 0.003 0.687 ± 0.003 0.640 ± 0.003 0.591 ± 0.003 0.543 ± 0.003 0.496 ± 0.003 0.443 ± 0.003 0.393 ± 0.003 0.343 ± 0.003 0.291 ± 0.003 0.241 ± 0.003 0.194 ± 0.002 0.147 ± 0.002 0.099 ± 0.002 0.050 ± 0.001 0.031 ± 0.001 0.013 ± 0.001 0±0
x1 1±0 0.999 ± 0.000 0.998 ± 0.000 0.997 ± 0.000 0.994 ± 0.000 0.991 ± 0.000 0.988 ± 0.000 0.984 ± 0.000 0.981 ± 0.001 0.978 ± 0.001 0.974 ± 0.001 0.969 ± 0.001 0.964 ± 0.001 0.958 ± 0.001 0.950 ± 0.001 0.941 ± 0.001 0.928 ± 0.001 0.911 ± 0.001 0.888 ± 0.002 0.854 ± 0.002 0.793 ± 0.002 0.654 ± 0.003 0.538 ± 0.003 0.326 ± 0.008 0±0
y1 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.001 ± 0.001 1.003 ± 0.002 1.007 ± 0.003 1.013 ± 0.003 1.020 ± 0.004 1.028 ± 0.004 1.036 ± 0.005 1.044 ± 0.005 1.053 ± 0.006 1.061 ± 0.007 1.07 ± 0.008 1.08 ± 0.009 1.09 ± 0.01 1.10 ± 0.011 1.11 ± 0.011 1.11 ± 0.013 1.13 ± 0.016 1.14 ± 0.021 1.15 ± 0.032 1.16 ± 0.039 1.16 ± 0.047 1.17 ± 0.053
γ1
1.24 ± 0.064 1.24 ± 0.056 1.23 ± 0.044 1.22 ± 0.035 1.19 ± 0.021 1.16 ± 0.014 1.13 ± 0.011 1.10 ± 0.009 1.08 ± 0.008 1.066 ± 0.007 1.052 ± 0.006 1.041 ± 0.005 1.032 ± 0.005 1.024 ± 0.004 1.019 ± 0.003 1.014 ± 0.003 1.01 ± 0.003 1.007 ± 0.002 1.005 ± 0.002 1.003 ± 0.002 1.001 ± 0.001 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000 1.000 ± 0.000
γ2
Table 6. (Vapor + Liquid) Equilibrium Data for Temperature T, Amount of Substances in Equilibrium Cell n1 and n2, Total Composition z1, Measured Pressure pmeas and Pressure Obtained from the Legendre Model pLeg, Liquid-Phase Mole Fraction x, Vapor-Phase Mole Fraction y, and Liquid Activity Coefficient γ, for the System DME (1) + Diethylsulfide (2)a
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in Hynynen et al.19 was used for the calculation of maximum theoretical error of the total molar composition in the cell (24 combinations).
Vapor phase fugacity coefficients were obtained from the Soave−Redlich−Kwong (SRK) equation of state utilizing quadratic mixing rules in the attractive parameter and linear in covolume.13 Binary interaction parameters in the quadratic part of the mixing rule were not regressed and their values were set to zero. For the Poynting factor calculation the Rackett equation was employed.14 Table 3 shows the properties of the compounds used in the data reduction scheme. Static Total Pressure Method. The temperature, system total pressure, and the equilibrium cell composition were measured. The corresponding vapor and liquid compositions were determined by using the Legendre polynomials for liquid activity coefficients description.15 Barker’s method was used for the data regression.16 The target of the data regression was to be able to describe the total pressure of the system of all measured points at one temperature. The number of parameters of the Legendre polynomial was increased until the absolute average deviation of the regression reached the value of uncertainty of the pressure measurement or until the pressure residual did not decrease significantly. Uusi-Kyyny et al.10 reported the details of this regression approach. VLEFIT software17 developed at Aalto University was used for the data regression. Also the Wilson activity coefficient model18 parameters obtained with Barker’s method are presented. The relative error in pressure was used as the Barker method objective function (O), as is shown in eq 4. NVLE is the total number of points i in question for data regression, pi,calc is the pressure obtained from the model and measured pressure is Pi,meas. O=
1 NVLE
NVLE
∑ i=1
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RESULTS AND DISCUSSION Static Total Pressure Measurements. Table 2 shows that pure component vapor pressures determined in this work were well in line with the correlations presented in the literature. The measured equilibrium data, including the activity coefficients are presented in Tables 4 to 6. Equilibrium phase compositions are presented in Figure 1. A positive deviation from Raoult’s law was observed for the measured systems.
Figure 1. Experimental pressure and liquid and vapor phase mole fractions. DME (1) + thiophene at 335.6 K: ●, x; ○, y. DME (1) + thiophene at 308.1 K: x, ▲; y, △. DME(1) + 2-methyl-2-propanethiol at 336.7 K: x ⧫, y ◊; DME(1) + diethylsulfide at 336.6 K: x ■, y □.
|pi ,calc − pi ,meas | pi ,meas
The measurements were considered to be of good quality based on the correct pure components vapor pressure and the ability of the Legendre polynomials to describe the total pressure. Additionally a regression with the Barkers methods using the Wilson equation as the activity coefficient model was made. The Wilson equation gave infinite dilution activity coefficient values close in comparison to the Legendre polynomials as are presented in Table 7.
(4)
Circulation Still Measurements. The VLEFIT software17 was used for the calculation of the activity coefficients. The properties and parameters used for the processing of the measurements are presented in Table 2. The liquid phase activity coefficient model parameters are not presented here since the number of measured equilibrium points is small. Additionally the compositions of the measured data points are near the pure 1-hexene end (x1‑hexene > 0.9). Error Analysis of the Static Total Pressure Measurements. The liquid density correlation maximum uncertainty estimate was obtained from the comparison of measured density against the correlation used. The density values at the temperature relevant for the regression of the data from (283.15 K to 338 K) was considered The values of the maximum error of density in the temperature range relevant for these systems was 1.1 % for DME, 0.02 % for thiophene, 0.07 % for 2-methyl-2-propanethiol, and 0.06 % for diethylsulfide. The uncertainty of the two pump volumes used for the addition of the components was ± 0.02 cm3. The uncertainty of the two pumps temperature measurement was ± 0.1 K. Pump pressure uncertainty estimate was ± 20 kPa. Pump temperature and pressure uncertainty affected the uncertainty in the density and the uncertainty in the compressibility of the liquid inside the pump. The cell temperature measurements uncertainty was ± 0.03 K and the cell pressure measurement uncertainty was ± 0.4 kPa. The uncertainties in the measured values of the temperature, the pressure, and the overall molar composition determined the uncertainty estimate of the reduced data. The method presented
Table 7. Legendre Liquid Activity Coefficient Model Parameters (Legendre, ai,j), Absolute Average Pressure Residuals (|△p|), and Infinite Dilution Activity Coefficients (γ1∞ and γ2∞), Wilson Liquid Activity Coefficient Model Parameters (Wilson λi,j), Absolute Average Vapor Phase Composition Mole Fraction Residuals (|△y|). System 1 (DME (1) + Thiophene (2) at 335.6 K), System 2 (DME (1) + Thiophene (2) at 308.1 K), System 3 (DME (1) + 2-Methyl-2propanethiol (2)), System 4 (DME(1) + Diethylsulfide(2)) Legendre, a0,0 Legendre, a1,0 Legendre, a2,0 Legendre, a3,0 Legendre, a4,0 |△p|/kPa Legendre γ1∞ and γ2∞ Wilson λ1,2/K Wilson λ2,1/K |△p| /kPa Wilson γ1∞ and γ2∞ 962
system 1
system 2
system 3
system 4
0.22042711 0.053679091 0.012880655 −0.007844611 na 0.4 1.22 and 1.35
0.184418 0.0520915 0.0100244 −0.0148409 na 0.5 1.17 and 1.26 −85.344 194.394 1.0 1.14 and 1.30
0.181393 0.100736 0.0397125 0.00989719 0.00265646 0.7 1.12 and 1.40
0.185101 0.0393953 0.00396423 −0.0089877 −0.00356649 0.5 1.17 and 1.24
−23.6896 193.385 0.9 1.11 and 1.38
47.7408 49.5107 1.0 1.15 and 1.27
−62.141 185.92 1.0 1.19 and 1.36
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(6) Design Institute for Physical Properties. DIPPR Project 801, full version; Thermophysical Properties Laboratory: Provo, Utah, 2005 (accessed at Knovel.com). (7) Uusi-Kyyny, P.; Sapei, E.; Pokki, J.-P.; Pakkanen, M.; Alopaeus, V. Vapor−liquid equilibrium for dimethyl disulfide + butane, + trans-but-2ene, + 2-methylpropane, + 2-methylpropene, + ethanol, and 2-ethoxy-2methylpropane. J. Chem. Eng. Data 2011, 56, 2501−2510. (8) Reid, R. C.; Prausnitz, J. M.; Poling, B. E. The Properties of Gases and Liquids, 4th ed.; McGraw-Hill: New York, 1988. (9) Green, D. W.; Perry, R. H. Perry’s Chemical Engineers’ Handbook, 8th ed.; McGraw-Hill: New York, 2007. (10) Uusi-Kyyny, P.; Pokki, J.-P.; Laakkonen, M.; Aittamaa, J.; Liukkonen, S. Vapor−liquid equilibrium for the binary systems 2methylpentane + 2-butanol at 329.2 K and n-hexane + 2-butanol at 329.2 and 373.2 K with a static apparatus. Fluid Phase Equilib. 2002, 201, 343− 358. (11) Yerazunis, S.; Plowright, J., D.; Smola, F., M. Vapor−liquid equilibrium determination by a new apparatus. AIChE J. 1964, 10, 660− 665. (12) Uusi-Kyyny, P.; Pokki, J.-P.; Aittamaa, J.; Liukkonen, S. Vapor− liquid equilibrium for the binary systems of 3-methylpentane + 2methyl-2-propanol at 331 K and + 2-butanol at 331 K. J. Chem. Eng. Data 2001, 46, 754−758. (13) Soave, G. Equilibrium constants from a modified Redlich−Kwong equation of state. Chem. Eng. Sci. 1972, 27, 1197−1203. (14) Rackett, H. G. Equation of state for saturated liquids. J. Chem. Eng. Data 1970, 15, 514−517. (15) Gmehling, J.; Onken, U. Vapour−Liquid Data Collection; DECHEMA Chemistry Data Series, Part 1; DECHEMA: Frankfurt/ Main, 1977; Vol. 1. (16) Barker, J. A. Determination of activity coefficients from total pressure measurements. Aust. J. Chem. 1953, 6, 207−210. (17) Aittamaa, J.; Pokki, J.-P. User Manual of Program VLEFIT; Helsinki University of Technology: Espoo, Finland, 2003. (18) Wilson, G., M. Vapor−liquid equilibrium. XI. A new expression for the excess free energy of mixing. J. Am. Chem. Soc. 1964, 86, 127− 130. (19) Hynynen, K.; Uusi-Kyyny, P.; Pokki, J.-P.; Pakkanen, M.; Aittamaa, J. Isothermal vapor liquid equilibrium for 2-methylpropene + methanol, + 1-propanol, + 2-propanol, + 2-butanol, and + 2-methyl-2propanol binary systems at 364.5 K. J. Chem. Eng. Data 2006, 51, 562− 568. (20) Sapei, E.; Zaytseva, A.; Uusi-Kyyny, P.; Kim, Y.; Keskinen, K. I.; Aittamaa, J. Vapor−Liquid equilibrium for binary system of thiophene + n-hexane at (338.15 and 323.15) K and thiophene + 1-hexene at (333.15 and 323.15) K. J. Chem. Eng. Data 2006, 51, 2203−2208. (21) Sapei, E.; Zaytseva, A.; Uusi-Kyyny, P.; Kim, Y.; Keskinen, K. I.; Aittamaa, J. Vapor−liquid equilibrium for binary system of 1propanethiol, thiophene, and diethyl sulfide with toluene at 90.03 kPa. J. Chem. Eng. Data 2006, 51, 1372−1376.
Circulation Still Measurements. Pure component vapor pressures for the 1-hexene and 2-methyl-2-propanethiol have already been measured with the equipment used in this work.20,21 Vapor pressure equation parameters for both components with their advisable range of use are presented in Table 3. The VLE measurements points with their corresponding activity coefficients are reported in Table 8. Table 8. (Vapor + Liquid) Equilibrium Data for the 1-Hexene (1) + 1-Propanethiol (2) System. Liquid-Phase Mole Fraction x and Vapor-Phase Mole Fraction y, Temperature T, Pressure p, and Activity Coefficient γ* x1
y1
T/K
p/kPa
γ1
1.0000 0.9596 0.9245 1.0000 0.9582 0.9207 1.0000 0.9608
1.0000 0.9541 0.9163 1.0000 0.9528 0.9124 1.0000 0.9555
328.15 328.15 328.16 336.09 335.84 335.79 335.74 335.64
77.0 77.4 77.5 99.8 99.8 99.9 98.7 98.7
1.00 1.00 0.99 1.00 1.00 1.00 1.00 1.00
γ2 1.31 1.28 1.30 1.27 1.30
*
u(x1) = 0.003, u(y1) = 0.003, u(T) = 0.05 K, u(p) = 0.17 kPa
The measured system shows positive deviation from Raoult’s law and azeotropic behavior. The reactivity of the 1-hexene and 2-methyl-2-propanethiol system was confirmed as the boiling point temperature rose during isobaric measurements at x2‑methyl‑2‑propanethiol > 0.1. Additionally a peak corresponding to a component with higher boiling point than 1-propanethiol and 1-hexene was detected in the GC analysis for samples. The measured points presented in this research showed no additional peaks in the GC analysis. Measurement of alkene + thiol VLE is challenging. One possibility for the measurements of these systems over a wide composition range is to use a flow-through type of apparatus. The second possibility is to measure such alkene + thiol systems for which the thiol−ene reaction does not easily take place. Less reactive behavior can be possibly be due to thermodynamic constraints or steric hindrance.
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AUTHOR INFORMATION
Corresponding Author
*Fax: +358 9 470 22694. E-mail: petri.uusi-kyyny@aalto.fi. Funding
The authors acknowledge Academy of Finland for the financial support. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Fleisch, T. H.; Basu, A.; Sills, R. A. Introduction and advancement of a new clean global fuel: The status of DME developments in China and beyond. J. Nat. Gas Sci. Eng. 2012, 9, 94−107. (2) U.S. Department of Labor, Occupational Safety & Health Administration. Standard 1910.110Storage and handling of liquefied petroleum gases: U.S. Department of Labor: Washington, DC, 2007. (3) Giles, N. F.; Wilson, H. L.; Wilding, W. V. Phase equilibrium measurements on twelve binary mixtures. J. Chem. Eng. Data 1996, 41, 1223−1238. (4) Posner, T. Ber. Dtsch. Chem. Ges. 1905, 38, 646−657. (5) Yaws, C. L. Yaws’ Handbook of Thermodynamic and Physical Properties of Chemical Compounds; Knovel: Norwich, NY,2003 (accessed at Knovel.com). 963
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