Measurement and Correlation of Liquid–Liquid Equilibrium for

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Measurement and Correlation of Liquid−Liquid Equilibrium for Quaternary Systems of Water + Methanol or Ethanol + Ethyl Methyl Carbonate + Heptane at 25 °C Yao Chen,* Kai Cheng, Wanxia Feng, and Quanzhou Zhang Department of Chemistry, Jinan University, Guangzhou, 510632, China ABSTRACT: In this work, liquid phase compositions for mixtures of water + methanol + ethyl methyl carbonate (EMC) + heptane, water + ethanol + EMC + heptane, and water + methanol + EMC, water + ethanol + EMC, and water + EMC + heptane at 25 °C were measured at atmospheric pressure. The modified UNIQUAC activity coefficient model was employed to correlate the experimental tie-line data, and the results were compared with ones obtained with the extended UNIQUAC model. The consistency of the measured tie-line data was ascertained by applying the Othmer−Tobias equation.

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the immiscible binary systems.12 In this research, the ternary parameters obtained from the systems of water + methanol + heptane,13 water + methanol + heptane,14 water + EMC + methanol, water + EMC + ethanol, and water + EMC + heptane are needed to correlate well quaternary LLE.

INTRODUCTION The addition of oxygenates such as ethers and alcohols to gasoline can effectively improve its octane number, but methyl tert-butyl ether (MTBE) which is used as a gasoline additive will lead to groundwater contamination and is nonbiodegradable.1 Recently environmentally conscious researchers have studied substitute materials such as dimethyl carbonate and diethyl carbonate2−4 which are able to enhance the octane number of gasoline and reduce environmental pollution. Ethyl methyl carbonate (EMC) has a high oxygen content, low toxicity, bioaccumulation persistence, and low solubility in water. It is recognized as an environmentally benign chemical and may be a promising gasoline additive to replace MTBE.5 The addition of EMC can enhance the octane rating of gasoline and reduce carbon monoxide emissions. However, the solubility of water in the hydrocarbon may increase if EMC is added into gasoline, and it would reduce the possibility of forming an aqueous phase in the gasoline petrol transfer system. In addition, if the addition of EMC can increase the solubility of the hydrocarbon in the aqueous phase, then a greater hydrocarbon concentration in the groundwater might be expected when gasoline is processed. Therefore, it is necessary to research what changes will occur in hydrocarbon−water miscibility after the addition of EMC. Reliable liquid−liquid equilibrium (LLE) data are crucial to understand solubility behavior of the components, and provide a scientific basis for developing gasoline additives. Besides, quaternary LLE data are required so as to test the correlation ability of the solution models. In this study, we present the entire range of LLE data for the quaternary systems of water + methanol + EMC + heptane and water + ethanol + EMC + heptane. The extended and modified UNIQUAC models6,7 were used to correlate the measured LLE data. The vapor−liquid equilibrium (VLE) data were needed to get the binary parameters for completely miscible binary systems.8−11 and mutual solubility data were used to get the binary parameters for © 2017 American Chemical Society

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EXPERIMENTAL SECTION The EMC, methanol, ethanol, and heptane with mass fraction of 0.995, 0.995, 0.997, and 0.980, respectively, together with bidistilled water, were used in this work. The purities of components were verified by gas chromatography which gave mass fractions as shown in Table 1. LLE experiments data were Table 1. Purities and Suppliers of Chemicals chemical name

CAS no.

purity

EMC (AR)a

623-53-0

0.994b

methanol (AR)

67-56-1

0.994b

ethanol (AR)

64-17-5

0.997b

heptane (AR)

142-82-5

0.996b

supplier Xiya-reagent Co. (Shanghai,China) Guangzhou-reagent Co. (Guangzhou,China) Guangzhou-reagent Co. (Guangzhou,China) Guangzhou-reagent Co. (Guangzhou,China)

analysis methodc GC GC GC GC

a

AR means for analytical reagent. bThe purity is represented by mass fraction. cGC: gas chromatography.

measured at the conditions of T = 25 °C and p = 100 kPa. The quaternary mixtures were prepared from water, methanol, or ethanol and preprepared binary mixtures {x3′ EMC + (1 − x3′) heptane}. The mole fraction of EMC, x3′, is about equal to 0.20, Special Issue: Memorial Issue in Honor of Ken Marsh Received: December 12, 2016 Accepted: March 13, 2017 Published: March 23, 2017 2516

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Table 2. LLE Data for Ternary Mixtures of Water + Methanol + EMC, Water + Ethanol + EMC, and Water + EMC + Heptane at T = 25 °C and p = 100 kPaa x1I 0.996 0.961 0.949 0.935 0.926 0.916 0.907 0.889 0.876

Figure 1. Phase equilibria of (water + methanol + EMC + heptane) and (water + ethanol + EMC + heptane). x3′ denotes quaternary section planes.

0.975 0.969 0.954 0.948 0.941 0.930 0.920 0.907

0.40, 0.60, and 0.80, respectively. The tetrahedral phase diagram formed by pseudoternary systems corresponding to distinct planes is shown in Figure 1. The mixtures of volume (60 to 100) cm3 were charged to a equilibration cell and stirred for 3 h in a constant temperature water bath, and then the mixtures were allowed to settle for 3 h in order to let the mixtures separate into two liquid phases completely. The samples were taken from the aqueous and organic phases by using two syringes. The liquid samples were analyzed by a gas chromatograph (GC-14C) equipped with a thermal conductivity detector. A Porapak QS column (2.5 m × 3 mm) was used to separate well each component. The oven temperature was increased from an initial 423.15 K to a final 483.15 K. The temperatures were set at 493.15 and 518.15 K for detector and injection, respectively. The hydrogen gas with the flow rate of 70 cm3·min−1 was used as the carrier gas. The peak area of each component was measured with a chromatopac (N 2000), and calibrated by gravimetrically prepared mixtures and converted to mole fraction. Each sample was analyzed more than three times. The uncertainty of the experimental tie-line data is 0.006 in mole fraction.

0.992 0.992 0.992 0.992 0.993 0.993 0.993 0.994

x2I

x3I

x1II

x2II

Water (1) + Methanol (2) + EMC (3) 0.000 0.004 0.091 0.000 0.029 0.010 0.104 0.011 0.039 0.012 0.130 0.023 0.050 0.015 0.146 0.031 0.057 0.017 0.165 0.038 0.064 0.020 0.182 0.045 0.071 0.022 0.213 0.054 0.082 0.029 0.243 0.065 0.088 0.036 0.271 0.073 Water (1) + Ethanol (2) + EMC (3) 0.018 0.007 0.115 0.029 0.023 0.008 0.144 0.042 0.037 0.009 0.219 0.059 0.042 0.010 0.256 0.077 0.045 0.014 0.301 0.078 0.050 0.020 0.396 0.096 0.056 0.024 0.468 0.106 0.066 0.027 0.487 0.109 Water (1) + EMC (2) + Heptane (3) 0.008 0.000 0.037 0.794 0.008 0.000 0.032 0.749 0.008 0.000 0.026 0.692 0.008 0.000 0.018 0.642 0.007 0.000 0.015 0.583 0.007 0.000 0.011 0.509 0.007 0.000 0.009 0.466 0.006 0.000 0.006 0.420

x3II 0.909 0.885 0.847 0.823 0.797 0.773 0.733 0.692 0.656 0.856 0.814 0.722 0.667 0.621 0.508 0.426 0.404 0.169 0.219 0.282 0.340 0.402 0.480 0.525 0.574

a Standard uncertainties u are u(T) = 0.05 K, u(x) = 0.006, and u(p) = 10 kPa. I, aqueous phase; II, organic phase.

the experimental and calculated mole fraction x of LLE data by minimizing the objective function, which is defined as follows:

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CALCULATED RESULTS AND DISCUSSION Table 2 presents the LLE data for the water + methanol + EMC, water + ethanol + EMC, and water + EMC + heptane at 25 °C. Table 3 lists the experimental LLE data for the water + methanol + EMC + heptane and water + ethanol + EMC + heptane at 25 °C. Figure 2 shows the experimental tie-lines for the ternary systems of water + EMC + heptane, water + methanol + EMC, and water + ethanol + EMC, and those correlated using the modified UNIQUAC model. Binary pairs heptane−water and water−EMC are partially miscible, and pairs EMC−methanol or ethanol or heptane are completely miscible. The slopes of the tie-lines for the water + methanol + EMC are much over zero, while those for the water + ethanol + EMC are below zero, as shown in Figure 2. It indicates that ethanol is more soluble than methanol in the organic phase. The optimum UNIQUAC interaction parameters were determined by these data. The values of binary parameters aij and bij are shown in Table 4. The extended and modified UNIQUAC models were fitted to the experimental data8−12 using a calculation program by Prausnitz et al.15 The binary parameters, for the methanol−EMC, ethanol−EMC, and EMC−heptane, were obtained by the regression of the measured LLE data for the water + methanol + EMC, water + ethanol + EMC and water + EMC + heptane. The optimization results were judged by calculating the corresponding root-mean-square deviation (rmsd) values. The rmsd value was calculated from the difference between

exp cal 2 F = 102[∑ min ∑ ∑ (xijk − xijk ) /M ]0.5 k

i

j

(1)

here i = 1 to 3 for ternary mixtures or i = 1 to 4 for quaternary mixtures, j = 1, 2 (phases), k = 1 to n (tie lines). Table 5 lists the ternary parameters, along with the rmsd values between the calculation and experimental LLE. The average rmsd values of correlated results obtained from the models by using the binary and ternary parameters were 1.78 mol % and 0.69 mol % for the extended and modified UNIQUAC models, respectively. The correlated results are better than the predicted ones with the binary parameters alone. Obviously, the results obtained by the modified UNIQUAC model are superior to the extended UNIQUAC model. The calculation results for four component systems are displayed in Table 6. The predicted results were achieved by fitting the models to experimental LLE with the binary and ternary parameters, while the quaternary parameters are additionally needed to get the correlated ones. The systems belong to type 2 quaternary LLE behavior, which is composed of the type 116 systems water + methanol or ethanol + heptane and water + methanol or ethanol + EMC, and the type 216 system water + EMC + heptane. The mean rmsd values in correlating quaternary LLE were individually 2.25% and 1.31% for the 2517

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Table 3. LLE Data for Quaternary Mixtures of Water + Methanol + EMC + Heptane and Water + Ethanol + EMC + Heptane at T = 25 °C and p = 100 kPaa x1I

x2I

x3I

x1II

x2II

x3II

x1I

{x1water + x2methanol + x3EMC + (1 − x1 − x2 − x3)heptane} x3′ = 0.20c 0.959 0.037 0.004 0.000 0.001 0.149 0.909 0.086 0.005 0.000 0.001 0.145 0.858 0.136 0.006 0.000 0.001 0.136 0.802 0.192 0.006 0.000 0.002 0.108 0.753 0.239 0.008 0.000 0.003 0.098 0.707 0.285 0.008 0.000 0.004 0.070 0.656 0.336 0.008 0.000 0.005 0.059 0.614 0.377 0.009 0.000 0.007 0.045 0.554 0.437 0.009 0.000 0.008 0.030 0.498 0.493 0.009 0.000 0.009 0.025 x3′ = 0.40c 0.961 0.032 0.007 0.000 0.001 0.314 0.914 0.079 0.007 0.000 0.002 0.309 0.862 0.130 0.008 0.000 0.004 0.274 0.811 0.179 0.010 0.000 0.005 0.244 0.762 0.224 0.014 0.000 0.006 0.204 0.702 0.283 0.015 0.000 0.008 0.173 0.647 0.337 0.016 0.000 0.009 0.119 0.600 0.383 0.017 0.000 0.010 0.082 0.546 0.435 0.019 0.000 0.011 0.068 0.497 0.484 0.019 0.000 0.011 0.051 x3′ = 0.60c 0.958 0.034 0.008 0.000 0.006 0.513 0.931 0.061 0.008 0.000 0.009 0.506 0.883 0.108 0.009 0.000 0.012 0.494 0.811 0.172 0.017 0.000 0.018 0.458 0.754 0.227 0.019 0.006 0.019 0.408 0.695 0.280 0.025 0.012 0.024 0.330 0.632 0.338 0.030 0.013 0.029 0.248 0.589 0.380 0.031 0.013 0.033 0.200 0.537 0.431 0.032 0.013 0.037 0.167 0.500 0.467 0.033 0.013 0.040 0.113 x3′ = 0.80c 0.963 0.029 0.008 0.000 0.011 0.757 0.933 0.058 0.009 0.000 0.018 0.744 0.876 0.110 0.014 0.015 0.028 0.702 0.809 0.172 0.019 0.026 0.038 0.665 0.751 0.224 0.025 0.035 0.049 0.611 0.692 0.273 0.035 0.036 0.059 0.551 0.647 0.311 0.042 0.041 0.068 0.483 0.602 0.355 0.043 0.044 0.085 0.345 0.551 0.399 0.050 0.046 0.098 0.205 0.498 0.451 0.051 0.050 0.109 0.148

x2I

x3I

x1II

x2II

x3II

{x1water + x2ethanol + x3EMC + (1 − x1 − x2 − x3)heptane} x3′ = 0.20c 0.978 0.018 0.004 0.000 0.005 0.148 0.925 0.070 0.005 0.000 0.010 0.131 0.884 0.109 0.007 0.000 0.014 0.100 0.844 0.147 0.009 0.000 0.017 0.075 0.800 0.190 0.010 0.000 0.018 0.056 0.768 0.221 0.011 0.000 0.020 0.045 0.735 0.253 0.012 0.000 0.024 0.037 0.704 0.284 0.012 0.000 0.026 0.032 0.665 0.323 0.012 0.000 0.028 0.024 0.635 0.351 0.014 0.000 0.030 0.021 x3′ = 0.40c 0.977 0.018 0.005 0.000 0.012 0.307 0.931 0.061 0.008 0.000 0.018 0.286 0.883 0.106 0.011 0.000 0.022 0.239 0.846 0.139 0.015 0.000 0.024 0.182 0.806 0.174 0.020 0.000 0.024 0.133 0.767 0.212 0.021 0.000 0.026 0.104 0.725 0.252 0.023 0.000 0.027 0.075 0.688 0.289 0.023 0.000 0.029 0.061 0.657 0.318 0.025 0.000 0.033 0.050 0.625 0.350 0.025 0.000 0.034 0.043 x3′ = 0.60c 0.977 0.017 0.006 0.000 0.023 0.512 0.930 0.053 0.017 0.000 0.031 0.456 0.875 0.101 0.024 0.003 0.039 0.435 0.832 0.141 0.027 0.006 0.041 0.412 0.785 0.181 0.034 0.010 0.044 0.258 0.743 0.218 0.039 0.015 0.046 0.182 0.717 0.244 0.039 0.017 0.053 0.145 0.676 0.283 0.041 0.019 0.058 0.110 0.638 0.319 0.043 0.020 0.059 0.090 0.604 0.352 0.044 0.020 0.059 0.066 x3′ = 0.80c 0.977 0.017 0.006 0.002 0.023 0.733 0.923 0.061 0.016 0.005 0.037 0.671 0.870 0.103 0.027 0.010 0.050 0.592 0.827 0.143 0.030 0.010 0.064 0.522 0.772 0.188 0.040 0.014 0.074 0.428 0.729 0.221 0.050 0.023 0.085 0.324 0.701 0.248 0.051 0.028 0.099 0.251 0.659 0.283 0.058 0.034 0.103 0.178 0.619 0.317 0.064 0.034 0.114 0.143 0.572 0.354 0.074 0.038 0.122 0.119

b

b

a

Standard uncertainties u are u(T) = 0.05 K, u(x) = 0.006, and u(p) = 10 kPa. bObtained by mixing pure water and methanol or ethanol with the binary mixtures of {x3′EMC + (1 − x3′)heptane}. cMole fraction of EMC in the binary mixtures. I, aqueous phase; II, organic phase.

extended and modified UNIQUAC models. It states that the modified UNIQUAC model can exactly correlate multicomponent LLE than the extended UNIQUAC model. The experimental LLE and correlated results of the modified UNIQUAC model for the measured systems are shown in Figures 3 and 4. The addition of different amounts of EMC in the aqueous phase shows no measurable solubility of heptane. As shown in Table 3, EMC as a gasoline additive to the gasoline will not cause groundwater contamination when the gas leak occurs during transport.

The consistency of experimental LLE data can be determined by applying the Othmer−Tobias equation17 showed in the following equation. ln[(1 − x 2II)/x 2II] = a + b ln[(1 − x1I)/x1I]

(2)

Here a and b are adjustable parameters of the Othmer−Tobias equation. I denotes the aqueous phase and II is the organic phase. The correlation factor, R2, shown in Table 7, is more than 0.96. It means a good degree of reliability of the measured LLE data. 2518

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Figure 3. Experimental and calculated LLE of the quaternary system (water + methanol + EMC + heptane) at T = 25 °C. ·- -·, experimental tie-lines; , correlated tie-lines of the modified UNIQUAC model.

Figure 2. Experimental and calculated LLE of ternary systems: (a) (water + methanol + EMC), (b) (water + ethanol + EMC), (c) (water + EMC + heptane) at T = 25 °C. ·- -·, experimental tie-lines; , correlated tie-lines of the modified UNIQUAC model.

Table 4. Calculated Results of Binary Phase Equilibrium Data Reduction modified UNIQUAC

extended UNIQUAC

system (1 + 2)

a12/K

a21/K

b12/K

b21/K

water + methanol water + ethanol methanol + heptane ethanol + heptane methanol + EMC ethanol + EMC EMC + heptane water + EMC water + heptane

158.59 −46.98 128.12 107.23 −129.20 −213.12 22.84 345.18 1022.10

−160.39 212.17 1188.97 1327.88 2114.30 2284.80 −6.79 778.89 1884.20

70.15 37.08 140.02 155.99 58.76 −280.51 604.71 388.69 1839.60

−71.81 157.12 1012.00 1325.83 216.24 2004.50 −549.87 665.82 2135.50

Table 5. Calculated Results for Ternary LLE at 25 °C na

τ231

water + methanol + EMC

8

water + ethanol + EMC

8

water + methanol + heptane

3

−0.332 −0.438c −0.972 −1.240 0.154 −1.336 −0.273 −0.634 −0.087 −0.111

system (1 + 2 + 3)

water + ethanol + heptane 13 water + EMC + heptane

8

b

τ132

τ123

0.096 0.371 0.713 3.817 −0.995 −1.025 −0.913 −0.818 −2.373 −0.035

4.088 2.800 5.232 1.515 −0.324 1.981 0.288 0.338 −0.047 −0.124

rmsd,e rmsd,f 1.19 2.17 1.71 2.24 1.62 14.15 4.78 13.61 1.59 2.86

Figure 4. Experimental and calculated LLE of quaternary system (water + ethanol + EMC + heptane) at T = 25 °C. ·- -·, experimental tie-lines; , correlated tie-lines of the modified UNIQUAC model.

0.61 1.78 0.90 1.36 1.07 3.94 0.55 0.79 0.33 1.02

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CONCLUSIONS The liquid−liquid equilibrium experiments for the water + methanol + EMC + heptane, water + ethanol + EMC + heptane, and water + methanol + EMC, water + ethanol + EMC, and water + EMC + heptane systems were performed at 25 °C under atmospheric pressure. The consistency of experimental tie-line data with the Othmer-Tobias equation was investigated and good agreement was obtained. The extended UNIQUAC model has a limitation when used for prediction using only the binary

a

Number of tie-lines. bModified UNIQUAC model. cExtended UNIQUAC model. dRoot-mean-square deviation (mol %). ePredicted results using binary parameters. fCorrelated results using binary and ternary parameters.

Table 6. Calculated Results for Quaternary LLE at 25 °C system (1 + 2 + 3 + 4)

na

water + methanol + EMC + heptane

40

water + ethanol + EMC + heptane

40

τ2341 b

3.214 0.010c 1.053 0.011

τ1342

τ1243

τ1234

rmsd,e

rmsd,f

4.921 −1.112 15.470 0.008

0.022 20.848 −19.547 −15.921

−8.354 −0.634 −3.717 −1.395

1.77 2.68 1.98 1.90

1.47 2.63 1.15 1.87

a

Number of data points. bModified UNIQUAC model. cExtended UNIQUAC model. dRoot-mean-square deviation (mol %). ePredicted results using binary and ternary parameters. fCorrelated results using binary, ternary and quaternary parameters. 2519

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(9) Hall, D. J.; Mash, C. J.; Penberton, R. C. Vapor-liquid equilibrium for the systems water + methanol, water + ethanol, methanol + ethanol and water + methanol + ethanol. NPL Rep. Chem. 1979, 95, 1−32. (10) Gmehling, J.; Onken, U. Vapor−Liquid Equilibrium Data Collection; DECHEMA: Frankfurt/Main, Germany, 1977; Vol. I, Part 2a. (11) Hongo, M.; Tsuji, T.; Fukuchi, K.; Arai, Y. Vapor-liquid equilibria of methanol + hexane, methanol + heptane, ethanol + hexane, ethanol + heptane, and ethanol + octane at 298.15 K. J. Chem. Eng. Data 1994, 39, 688−691. (12) Sørensen, J. M.; Arlt, W. Liquid−Liquid Equilibrium Data Collection; DECHEMA: Frankfurt/Main, Germany, 1979; Vol. V, Part 1. (13) Letcher, T. M.; Wootton, S.; Shuttle worth, B.; Heyward, C. Phase equilibria for (heptane + water + alcohol) at 298.2 K. J. Chem. Thermodyn. 1986, 18, 1037−1042. (14) Chen, Y.; Dong, Y. H.; Zhang, S. L. Quaternary liquid-liquid equilibria for (water + ethanol + diisopropyl ether + n-heptane) at 298.15 K. Chem. J. Internet 2006, 8, 66−72. (15) Prausnitz, J. M.; Anderson, T. F.; Grens, E. A.; Eckert, C. A.; Hsieh, R.; O’Connell, J. P. Computer Calculations for Multicomponent Vapor-Liquid and Liquid-Liquid Equilibria; Prentice Hall: Englewood Cliffs, NJ, 1980. (16) Sandler, S. I. Chemical and Engineering Thermodynamics; John Wiley and Sons: New York, 1998. (17) Othmer, D. F.; Tobias, P. E. The line correlation. Ind. Eng. Chem. 1942, 34, 693−696.

Table 7. Constants and Correlation Factors of Othmer− Tobias Equation system water + methanol + EMC water + ethanol + EMC water + EMC + heptane water + methanol + EMC + heptane

water + ethanol + EMC + heptane

x3′

a

b

R2

0.2 0.4 0.6 0.8 0.2 0.4 0.6 0.8

−0.207 −0.392 −33.371 4.362 4.336 3.212 2.169 3.174 3.236 2.636 1.830

−1.372 −1.039 −6.713 −1.328 −0.698 −0.581 −0.707 −0.546 −0.301 −0.304 −0.540

0.992 0.965 0.962 0.999 0.991 0.992 0.995 0.993 0.989 0.979 0.986

interaction parameters for the water + methanol + heptane and water + ethanol + heptane systems. While the extended and modified UNIQUAC models show smaller deviations when correlating the experimental LLE data. The successful correlation result of less than 2.3 mol % of rmsd is obtained. The results reveal that the models possess a good capability in correlating LLE of multicomponent systems.

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AUTHOR INFORMATION

Corresponding Author

*Fax: +86-20-85221697. E-mail: [email protected]. ORCID

Yao Chen: 0000-0002-3461-388X Funding

We are grateful to Prof. Zhou Lixin for providing us experimental funds. Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Eweis, J. B.; Chang, D. P. Y.; Schroeder, E. D.; Scow, K. M.; Morton, R. L.; Caballero, R. C. Meeting the challenge of MTBE biodegradation. Proc. Ann. Meet., Air Waste Manage. Assoc. 1997, 90, 121−129. (2) Pacheco, M. A.; Marshall, C. L. Review of dimethyl carbonate (DMC) manufacture and its characteristics as a fuel additive. Energy Fuels 1997, 11, 2−29. (3) Fang, Y. J.; Qian, J. M. Isobaric vapor-liquid equilibria of binary mixtures containing the carbonate group -OCOO-. J. Chem. Eng. Data 2005, 50, 340−343. (4) Chen, Y.; Wang, C.; Guo, J. T.; Zhou, X.; Wen, C. Phase equilibrium for quaternary systems of water + methanol + diethyl carbonate + methylbenzene or heptane or cyclohexane. J. Chem. Eng. Data 2015, 60, 2062−2069. (5) Zhang, X.; Zuo, J.; Jian, C. Experimental isobaric vapor-liquid equilibrium for binary systems of ethyl methyl carbonate + methanol, + ethanol, + dimethyl carbonate, or + diethyl carbonate at 101.3 kPa. J. Chem. Eng. Data 2010, 55, 4896−4902. (6) Nagata, I. Modification of the extended UNIQUAC model for correlating quaternary liquid-liquid equilibria data. Fluid Phase Equilib. 1990, 54, 191−206. (7) Tamura, K.; Chen, Y.; Tada, K.; Yamada, T.; Nagata, I. Representation of multicomponent liquid-liquid equilibria for aqueous and organic solutions using a modified UNIQUAC model. J. Solution Chem. 2000, 29, 463−488. (8) Koner, Z. S.; Phutela, R. C.; Fenby, D. V. Determination of the equilibrium constants water-methanol deuterium exchange reactions from vapour pressure measurements. Aust. J. Chem. 1980, 33, 9−13. 2520

DOI: 10.1021/acs.jced.6b01031 J. Chem. Eng. Data 2017, 62, 2516−2520