Vapor–Liquid Equilibrium for Ternary and Binary Mixtures of 2

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Vapor−Liquid Equilibrium for Ternary and Binary Mixtures of 2‑Isopropoxypropane, 2‑Propanol, and N,N‑Dimethylacetamide at 101.3 kPa Zhigang Zhang, Lei Yang, Yuan Xing, and Wenxiu Li* School of Chemical Engineering, Shenyang University of Chemical Technology, Shenyang 110142, China ABSTRACT: Vapor−liquid equilibrium (VLE) data of the 2-isopropoxypropane + 2-propanol + N,N-dimethylacetamide ternary system have been reported at 101.3 kPa, as well as for 2-isopropoxypropane + 2-propanol and 2-isopropoxypropane + N,N-dimethylacetamide + and 2-propanol + N,N-dimethylacetamide binary systems. From the results of the VLE data, it passed the thermodynamic consistency test. The universal functional (UNIFAC), universal quasichemical (UNIQUAC), nonrandom two-liquid (NRTL), and Wilson models were used to correlate the activity coefficients with its composition. The results indicate that these models allow a very good prediction of the phase equilibrium of the ternary system using the pertinent parameters of the binary systems. The 2-isopropoxypropane + 2-propanol binary azeotropes are eliminated by N,N-dimethylacetamide, and there is a significant change with phase equilibrium behavior. Hence, the N,N-dimethylacetamide appears to be an effective solvent.

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0.01 g·cm−3 and 0.0002, respectively. The purity of components was compared their normal refractive indices, densities, and boiling points with values6 of the corresponding literature as shown in Table 2. Apparatus and Procedure. In the present study, an all-glass equilibrium still (NGW, Wertheim, Germany) described by Hunsmann7 with provisions for both vapor and liquid recirculation was employed to measure isobaric VLE data. The total volumetric capacity of the apparatus is about 100 g·cm−3, Therefore, the total quantity of liquid required is small, and equilibrium is reached fairly fast. The system pressure was regulated by a voltage regulator, and the temperature was measured by a quartz thermometer. The measured pressure in the still was (101.3 ± 0.1) kPa, and the uncertainty of temperature is estimated to be 0.01 K. The equilibrium compositions of the liquid and condensed vapor were analyzed by an Agilent 7890A gas chromatograph equipped (GC) with a 30 m, 0.32 mm i.d., 0.25 μm capillary column and a flame ionization detector for quantification. The gas chromatography response peaks were integrated using an Agilent Chemstation. Injector, detector, and column temperatures were (472, 553, and 313) K, respectively. Each vapor and liquid composition should make at least three analyses. The standard deviation in the mole fraction was usually less than 0.001.

INTRODUCTION 2-Isopropoxypropane is a common solvent, and it is commonly used in chemical engineering enterprises and as a suitable gasoline additive.1,2 It is produced by dehydration of 2-propanol with adequate catalyst. The purification of 2-isopropoxypropane is a relatively complex process in traditional methods, because a minimum boiling point azeotrope3 will appear in the binary system of 2-isopropoxypropane +2-propanol at certain temperature. For solving the separation problem, many researchers use extractive distillation4,5 to separate them. Because the azeotropic mixture can be separated by adding solvent that improves the relative volatility. The vapor−liquid equilibrium (VLE) data require determination in some separation processes such as extractive distillation and the selection of solvents, In this case, we report VLE data for the ternary system 2-isopropoxypropane (1) + 2-propanol (2) + N,N-dimethylacetamide (3) and VLE data for the binary systems 2-isopropoxypropane (1) + 2-propanol (2) and 2-isopropoxypropane (1) + N,N-dimethylacetamide (3) and 2-propanol (2) + N,N-dimethylacetamide (3). Then, we use the universal functional (UNIFAC), universal quasichemical (UNIQUAC), Wilson, and nonrandom two-liquid (NRTL) equations to relate activity coefficients with compositions.

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EXPERIMENTAL SECTION Chemicals. The chemicals 2-isopropoxypropane, 2-propanol, and N,N-dimethylacetamide were purchased from Sinopharm Group Co. Ltd. The specifications of the used chemicals are summarized in Table 1. We use gas chromatography to determine all chemicals, and they failed to exhibit any significant impurities. The densities of the pure components were measured at 298.15 K using a vibrating tube density meter, and the refractive indexes were measured at 298.15 K using an Abbe refractometer. The uncertainties in density and refractive index measurements are © 2012 American Chemical Society

RESULTS AND DISCUSSION Vapor Pressure. The experimental vapor pressure of the pure components are listed in Table 3, and they were compared with these calculated by Antoine equation and the Antoine constant parameters8 are listed in Table 4.The vapor pressures Received: August 26, 2012 Accepted: December 13, 2012 Published: December 26, 2012 357

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Table 1. Specific Cations of Chemical Samples

a

chemical name

source

initial mass fraction purity

purification method

analysis method

2-isopropoxypropane 2-propanol N,N-dimethylacetamide

Sinopharm Group Sinopharm Group Sinopharm Group

0.9950 0.9950 0.9900

none none none

GCa GCa GCa

Gas−liquid chromatography.

Table 2. Density ρ, Refractive Index nD, and Normal Boiling Point Tb of Pure Components5 ρ(298.15 K)/g·cm−3

nD(298.15 K)

a

T(101.3 kPa)/K

component

exptl

lit.

exptl

lit.

exptl

lit.

2-isopropoxypropanea 2-propanola N,N-dimethylacetamidea

1.3651 1.3554 1.4352

1.3655 1.3594 1.4331

0.7183 0.7851 1.1128

0.7185 0.7849 1.1135

341.51 355.42 440.31

341.66 355.44 440.33

Standard uncertainties u are u(ρ) = 0.0002 g·cm−3, u(nD) = 0.0002, and u(T) = 0.05 kPa.

Table 3. Experimental Vapor Pressures of 2-Isopropoxypropane, 2-Propanol, and N,N-Dimethylacetamide at Different Temperatures 2-isopropoxypropanea

a

2-propanola

N,N-dimethylacetamidea

T/K

p/kPa exptl

p/kPa lit.

T/K

p/kPa exptl

p/kPa lit.

T/K

p/kPa exptl

p/kPa lit.

287.06 290.73 293.32 296.62 298.03 301.55 305.29 308.69 311.46 315.15 318.61 321.46 325.59 329.24 332.63 335.77 338.84 341.51

11.61 14.03 15.62 18.12 19.49 22.56 26.68 30.75 34.14 39.81 45.42 50.55 58.79 66.99 75.52 84.01 93.16 101.29

11.64 13.88 15.67 18.24 19.41 22.66 26.59 30.63 34.28 39.69 45.37 50.52 58.83 67.25 75.48 84.04 93.13 101.33

305.78 308.57 311.12 314.02 316.97 319.62 322.43 324.89 327.34 330.35 333.67 339.26 342.41 345.84 348.23 350.75 352.19 355.42

9.56 11.32 12.90 15.27 17.78 20.47 23.35 26.59 29.75 34.43 40.34 51.70 59.25 68.84 76.09 83.99 89.19 101.22

9.59 11.24 12.95 15.17 17.74 20.36 23.48 26.53 29.9 34.51 40.28 51.80 59.41 68.72 75.90 84.13 89.15 101.31

378.79 382.26 385.71 389.57 392.44 395.63 399.37 403.83 406.08 409.51 412.16 416.59 420.34 425.53 429.34 433.63 436.68 440.31

15.58 17.85 20.13 22.97 25.27 28.34 31.85 36.81 39.52 43.69 47.28 54.08 59.96 69.44 77.01 85.95 93.14 101.32

15.63 17.76 20.10 23.00 25.38 28.24 31.91 36.77 39.43 43.78 47.39 53.96 60.05 69.34 76.85 86.03 93.06 101.38

Standard uncertainties u are u(T) = 0.05 K and u(p) = 0.3 kPa.

Table 4. Antoine’s Coefficients for Pure Components

a

components

A

B

C

diisopropyl ethera isopropyl alcohola N,N-dimethylacetamidea

16.342 17.664 15.128

2895.7 3109.3 2885.9

−43.15 −73.546 −100.32

Parameters obtained in ref 8.

measured and those calculated by Antoine equation showed in Figures 1, 2, and 3. The results show that the vapor pressure matches well with the Antoine equation. Bi ln(pi0 /kPa) = Ai − T /K + Ci (1) Binary Systems. The VLE data of 2-isopropoxypropane (1) + 2-propanol (2) and 2-isopropoxypropane (1) + N,Ndimethylacetamide (3) and 2-propanol (2) + N,N-dimethylacetamide (3) are listed in Tables 5, 6, and 7 and plotted in Figures 4, 5, and 6. The activity coefficient γ of pure liquid i was calculated

Figure 1. Experimental vapor pressure for 2-isopropoxypropane: ■, experimental data. Solid line calculated from the Antoine equation. 358

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Table 5. Experimental VLE Data for 2-Isopropoxypropane (1) + 2-Propanol (2) System at 101.3 kPaa

Figure 2. Experimental vapor pressure for 2-propanol: ■, experimental data. Solid line calculated from the Antoine equation.

T/K

x1

y1

u(x)

u(y)

u(T)

355.42 352.94 350.39 348.39 346.61 345.02 343.92 342.97 342.23 341.63 341.10 340.57 340.13 339.73 339.39 339.18 339.13 339.30 339.71 340.37 341.51

0.000 0.029 0.066 0.102 0.142 0.189 0.232 0.281 0.331 0.382 0.439 0.499 0.555 0.613 0.672 0.728 0.785 0.842 0.894 0.947 1.000

0.000 0.106 0.213 0.295 0.368 0.434 0.483 0.529 0.567 0.600 0.632 0.660 0.685 0.709 0.733 0.757 0.784 0.817 0.856 0.912 1.000

0.002 0.004 0.005 0.002 0.001 0.003 0.005 0.003 0.005 0.004 0.006 0.002 0.003 0.004 0.002 0.006 0.008 0.004 0.002 0.002 0.001

0.001 0.003 0.007 0.004 0.006 0.002 0.003 0.002 0.006 0.008 0.005 0.002 0.001 0.005 0.003 0.004 0.002 0.003 0.007 0.004 0.006

0.07 0.02 0.04 0.05 0.02 0.02 0.03 0.05 0.05 0.03 0.02 0.06 0.04 0.01 0.01 0.06 0.09 0.04 0.03 0.01 0.02

γ1 2.556 2.429 2.316 2.194 2.044 1.919 1.790 1.667 1.559 1.454 1.359 1.286 1.221 1.165 1.118 1.076 1.039 1.012 0.996 1.000

γ2 1.000 1.015 1.029 1.041 1.051 1.065 1.076 1.091 1.112 1.141 1.184 1.253 1.332 1.441 1.583 1.753 1.977 2.262 2.605 3.093

a

The uncertainties of composition and temperature, that is, u(x), u(y), and u(T) with a 0.95 level of confidence, were listed. The maximum expanded uncertainties of the composition and temperature measurements were below 0.008 mole fraction and 0.09 K.

Table 6. Experimental VLE Data for 2-Isopropoxypropane (1) + N,N-Dimethylacetamide (3) System at 101.3 kPaa

Figure 3. Experimental vapor pressure for N,N-dimethylacetamide: ■, experimental data. Solid line calculated from the Antoine equation.

with the activity coefficient equation: γi =

ϕiPyi Pioxiϕis

exp[υiL(P − Pio)/RT ]

yixi, ϕi, ϕsi ,

Poi

(2)

vLi 9

where and are the vapor mole fraction, liquid mole fraction, vapor-phase fugacity coefficient, vapor-phase fugacity coefficient at saturation, vapor pressure, and liquid molar volume for component i, respectively. Vapor-phase fugacity coefficients, ϕi and ϕsi , were calculated from the Soave−Redlich− Kwong (SRK) equation of state,10 where the binary interaction parameter, kij, was set to 0. According to the activity coefficients exhibited in Tables 6 and 7, the 2-isopropoxypropane (1) + N,N-dimethylacetamide (3) system presents positive deviations from ideal behavior, and the 2-propylalcohol (2) + N,N-dimethylacetamide (3) system presents a slight deviation from ideal behavior. The binary experimental data passed the thermodynamic consistency test by the method of Fredenslund et al.11 Pertinent consistency details and statistics are presented in Table 8, and it can be seen that the consistency criteria (AADy < 0.1) was achieved using a two-parameter Legendre polynomial.

T/K

x1

y1

u(x)

u(y)

u(T)

440.31 437.04 435.32 429.41 421.68 401.27 388.26 375.56 368.99 364.66 355.89 351.54 348.94 346.82 345.69 344.57 343.99 343.61 343.13 342.43 342.34 342.08 341.51

0.000 0.002 0.004 0.009 0.022 0.061 0.102 0.158 0.195 0.225 0.288 0.342 0.393 0.446 0.502 0.569 0.622 0.686 0.734 0.832 0.916 0.959 1.000

0.000 0.102 0.135 0.256 0.426 0.695 0.798 0.879 0.906 0.913 0.935 0.939 0.94 0.945 0.952 0.961 0.966 0.971 0.972 0.983 0.991 0.994 1.000

0.002 0.004 0.001 0.005 0.003 0.003 0.006 0.008 0.003 0.002 0.006 0.007 0.003 0.005 0.004 0.003 0.003 0.006 0.002 0.005 0.004 0.003 0.003

0.005 0.003 0.003 0.006 0.004 0.002 0.002 0.001 0.004 0.002 0.001 0.003 0.005 0.009 0.003 0.005 0.002 0.002 0.004 0.006 0.005 0.007 0.002

0.03 0.05 0.07 0.02 0.02 0.01 0.04 0.06 0.05 0.03 0.07 0.05 0.03 0.02 0.05 0.06 0.02 0.01 0.04 0.07 0.02 0.05 0.06

γ1 4.829 3.301 3.114 2.471 2.221 2.094 2.051 2.042 2.011 2.071 1.996 1.883 1.782 1.652 1.525 1.429 1.318 1.237 1.106 1.016 0.992 1.000

γ3 1.000 0.971 0.979 0.988 0.993 0.995 0.036 1.051 1.104 1.265 1.497 1.849 2.223 2.467 2.527 2.504 2.560 2.677 3.065 3.135 3.148 3.501

a

The uncertainties of composition and temperature, that is, u(x), u(y), and u(T) with a 0.95 level of confidence, were listed. The maximum expanded uncertainties of the composition and temperature measurements were below 0.009 mole fraction and 0.07 K.

We used the Wilson,12 NRTL,13 UNIQUAC,14 and UNIFAC14 equations to correlate the activity coefficients. The parameters of 359

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Table 7. Experimental VLE Data for 2-Propanol (2) + N,N-Dimethylacetamide (3) System at 101.3 kPaa T/K

x2

y2

u(x)

u(y)

u(T)

440.31 427.31 418.87 410.88 404.33 397.99 392.84 388.05 383.52 379.31 375.44 372.18 369.08 366.47 364.32 362.48 360.90 359.42 358.05 356.73 355.42

0.000 0.063 0.115 0.171 0.222 0.282 0.336 0.394 0.448 0.496 0.551 0.601 0.656 0.712 0.745 0.802 0.841 0.875 0.911 0.951 1.000

0.000 0.283 0.443 0.563 0.652 0.731 0.783 0.825 0.861 0.895 0.928 0.949 0.965 0.976 0.985 0.988 0.991 0.994 0.996 0.998 1.000

0.003 0.001 0.005 0.002 0.002 0.007 0.004 0.002 0.001 0.002 0.003 0.002 0.004 0.005 0.003 0.002 0.005 0.006 0.004 0.003 0.001

0.005 0.001 0.002 0.005 0.003 0.005 0.002 0.005 0.006 0.003 0.001 0.005 0.002 0.002 0.005 0.004 0.002 0.003 0.006 0.002 0.004

0.06 0.03 0.01 0.05 0.02 0.03 0.07 0.04 0.05 0.03 0.03 0.01 0.05 0.06 0.03 0.02 0.02 0.04 0.06 0.09 0.05

γ2 0.623 0.619 0.629 0.646 0.675 0.706 0.742 0.778 0.808 0.843 0.873 0.904 0.932 0.947 0.968 0.979 0.988 0.994 0.998 1.000

γ3 1.000 0.963 0.975 0.988 1.002 1.009 1.015 1.007 1.016 1.015 1.013 1.012 0.998 0.981 0.763 0.858 0.864 0.788 0.791 0.767

Figure 5. Experimental VLE data for the 2-isopropoxypropane (1) + N,N-dimethylacetamide (3) system at 101.3 kPa: ●, experimental data. Smoothed data using the UNIFAC model with the parameters given in Table 11.

a

The uncertainties of composition and temperature, that is, u(x), u(y), and u(T) with a 0.95 level of confidence were listed. The maximum expanded uncertainties of the composition and temperature measurements were below 0.007 mole fraction and 0.09 K.

Figure 6. Experimental VLE data for 2-propanol (2) + N,N-dimethylacetamide (3) system at 101.3 kPa: ●, experimental data. Smoothed data using the UNIFAC model with the parameters given in Table 11.

Table 8. Consistency Test Statistics for the Binary Systems Figure 4. Experimental VLE data for the 2-isopropoxypropane (1) + 2-propanol (2) system at 101.3 kPa: ●, experimental data. Smoothed data using the UNIFAC model with the parameters given in Table 11.

A1a

A2a

AADyib

AADpc/kPa

1+2 1+3 2+3

0.5264 0.6847 0.5765

0.1682 0.2021 0.1052

0.0028 0.0026 0.0052

0.426 0.517 0.468

a Legendre polynomial parameters. bAverage absolute deviation in vaporphase composition. cAverage absolute deviation in pressure.

the equations were calculated by minimizing the objective function (OF): ⎛ T exptl − T calcd ⎞ i OF = ∑ ⎜⎜ i + |yiexptl − yicalcd |⎟⎟ exptl Ti ⎠ i=1 ⎝

system i + j

the equation proposed by Wisniak and Tamir15

N

m

T = xiTi + xjTj + xixj ∑ Ck(xi − xj)k

(3)

k=0

which are shown in Table 11, as well as the relevant statistics of each VLE. The experimental data were well matched with the UNIFAC equation and plotted in Figures 4, 5, and 6. The boiling point temperatures of each binary system were correlated with

(4)

where Ti is the boiling temperature, i(k) is the pure component, Ck and m are the binary coefficient and number of binary parameters, respectively, and all of the parameters were obtained by the 360

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Table 9. Coefficients, Average Deviation, and Root-Mean-Square Deviation in the Correlation of Boiling Points by the Tamir−Wisniak Equations

a

system i + j

C0

C1

C2

C3

1+2 1+3 2+3 1+2+3

−31.57 −180.70 −74.51

11.54 155.98 20.3

−26.06 −116.07 −16.95

8.39 86.47 31.95

A

B

−13.26

−12.17

D

AADTa/K

RMSDb/K

−36.51

0.07 0.14 0.12 0.18

0.05 0.08 0.09 0.05

C

5.43

Average absolute deviation in temperature. bRoot-mean-square deviation: 1/N{∑(Texptl − Tcalcd)2}0.5.

Table 10. Experimental VLE Data for 2-Isopropoxypropane (1) + 2-Propanol (2) + N,N-Dimethylacetamide (3) at 101.3 kPaa T/K

x1

y1

x2

y2

u(x1)

u(y1)

u(x2)

u(y2)

u(T)

γ1

γ2

γ3

341.76 341.69 341.98 342.31 341.76 342.23 341.61 341.66 341.95 342.49 341.83 341.59 342.64 342.16 342.21 342.41 348.08 348.31 342.83 344.51 344.67 348.84 349.48 348.81 353.59 349.90 351.84 357.64 361.09 368.15 368.26 384.77 388.16 411.08

0.991 0.894 0.562 0.694 0.520 0.732 0.473 0.336 0.647 0.288 0.597 0.533 0.231 0.409 0.346 0.461 0.096 0.086 0.435 0.134 0.155 0.061 0.077 0.186 0.104 0.211 0.223 0.142 0.121 0.097 0.026 0.039 0.052 0.011

0.995 0.981 0.881 0.931 0.878 0.978 0.865 0.767 0.972 0.725 0.973 0.947 0.692 0.921 0.872 0.966 0.431 0.413 0.968 0.587 0.676 0.398 0.451 0.843 0.705 0.914 0.965 0.891 0.879 0.894 0.269 0.701 0.921 0.564

0.001 0.093 1.999 0.081 0.211 0.023 0.246 0.403 0.018 0.542 0.018 0.106 0.581 0.129 0.236 0.029 0.884 0.881 0.024 0.668 0.531 0.767 0.641 0.248 0.389 0.136 0.025 0.133 0.132 0.087 0.474 0.143 0.014 0.071

0.003 0.011 0.113 0.059 0.115 0.009 0.129 0.229 0.012 0.272 0.011 0.042 0.304 0.065 0.117 0.015 0.568 0.586 0.012 0.411 0.317 0.597 0.545 0.141 0.281 0.063 0.005 0.078 0.087 0.061 0.713 0.235 0.011 0.277

0.002 0.003 0.002 0.002 0.004 0.003 0.002 0.001 0.007 0.005 0.002 0.003 0.006 0.001 0.002 0.004 0.008 0.002 0.005 0.003 0.003 0.002 0.005 0.002 0.003 0.004 0.001 0.003 0.002 0.002 0.002 0.006 0.001 0.002

0.004 0.005 0.002 0.001 0.003 0.004 0.002 0.008 0.005 0.003 0.001 0.003 0.002 0.002 0.006 0.003 0.004 0.005 0.002 0.001 0.002 0.003 0.003 0.004 0.002 0.001 0.004 0.002 0.002 0.003 0.001 0.002 0.002 0.003

0.001 0.003 0.002 0.002 0.002 0.006 0.001 0.002 0.003 0.002 0.002 0.004 0.003 0.002 0.001 0.007 0.006 0.004 0.004 0.008 0.002 0.005 0.003 0.002 0.002 0.006 0.001 0.001 0.003 0.001 0.002 0.004 0.008 0.002

0.005 0.002 0.004 0.008 0.002 0.003 0.004 0.005 0.001 0.007 0.006 0.004 0.004 0.009 0.002 0.003 0.003 0.002 0.002 0.006 0.001 0.004 0.004 0.003 0.003 0.002 0.002 0.003 0.003 0.004 0.002 0.002 0.006 0.003

0.05 0.03 0.01 0.04 0.02 0.02 0.01 0.03 0.06 0.05 0.02 0.02 0.04 0.05 0.03 0.03 0.05 0.07 0.06 0.08 0.03 0.02 0.02 0.01 0.04 0.04 0.05 0.03 0.06 0.02 0.02 0.08 0.04 0.02

0.991 1.094 1.547 1.311 1.680 1.309 1.828 2.278 1.486 2.447 1.618 1.779 2.897 2.212 2.479 2.042 3.658 3.886 2.139 3.993 3.955 5.194 4.571 3.611 4.671 3.337 3.143 3.837 4.021 4.189 4.689 5.302 4.808 6.263

3.304 0.209 0.994 1.257 0.964 0.677 0.933 1.009 1.169 0.859 1.077 0.706 0.890 0.875 0.863 0.889 0.867 0.889 0.843 0.964 0.933 1.019 1.084 0.745 0.799 0.580 0.231 0.539 0.531 0.435 0.928 0.577 0.247 0.635

2.229 1.324 0.953 1.425 0.857 1.707 0.707 0.507 1.558 0.561 1.363 1.011 0.672 0.978 0.852 1.189 1.223 0.733 1.156 0.438 0.638 0.687 0.326 0.668 0.527 0.793 0.823 0.684 0.628 0.568 0.369 0.427 0.351 0.388

a The uncertainties of composition and temperature, that is, u(x), u(y), and u(T) with a 0.95 level of confidence, were listed. The maximum expanded uncertainties of the composition and temperature measurements were below 0.009 mole fraction and 0.08 K.

data, we can get the conclusion that the four models represent the data successfully. Thus, these models can be used to calculate boiling points from liquid-phase compositions at the system pressure. We correlated the boiling points by the equation, and it was suggested by Wisniak and Tamir.

least-squares method. The root-mean-square deviation and average deviation of boiling temperatures are listed in Table 9. Ternary System. VLE data of 2-isopropoxypropane (1) + 2-propanol (2) + N,N-dimethylacetamide (3) at 101.3 kPa are determined in Table 10. The ternary data were found to be thermodynamically consistent by the Wisniak and Tamir modification of the McDermott−Ellis16 test (D < Dmax at all data points) and the Wisniak L-W test17 (0.92 < Li/Wi < 1.10). The VLE data were predicted using the UNIFAC, UNIQUAC, Wilson, and NRTL equations. The binary interaction parameter and quality of the prediction were acquired from the regression of binary data. Table 11 shows the mean absolute deviations of vapor phase mole fractions between experimental and calculated. From these

3

T=

3

∑ xiTi + ∑ [xiyi ∑ Ck(xi − xj)k ] + x1x2 i=1

k=0

x3[A + B(x1 − x 2) + C(x1 − x3) + D(x 2 − x3)] (5)

where Ti is the boiling temperature, i(k) is the pure component, Ck and m are the binary coefficient and number of binary 361

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Table 11. Experimental VLE Data Reduction with the Wilson, NRTL, UNIQUAC, and UNIFAC Models model Wilsonc

NRTL

UNIQUACe

UNIFACf

Aij

Aji

system i + j

J·mol−1

J·mol−1

1+2 1+3 2+3 1 + 2 + 3d 1+2 1+3 2+3 1 + 2 + 3d 1+2 1+3 2+3 1 + 2 + 3d 1+2 1+3 2+3 1 + 2 + 3d

−472.25 352.26 490.45

4385.34 5716.51 −1617.76

2738.51 −3719.80 −2899.06 −2727.58 −2754.13 −1419.58

RMSD

892.27 2040.0 −3475.27

α

AADTa

AADy1b 0.0064 0.0052

0.3 0.3 0.3

0.38 0.09 0.80 0.73 0.12 0.17 0.46 0.52 0.47 0.33 0.51

−1193.35 −1088.99 2024.63

0.45 0.12 0.57 0.83

0.0078 0.0046 0.0068 0.0054 0.0081 0.0023

AADy2b

0.0014 0.0041

0.0058 0.0035 0.0036 0.0075

0.0062 0.0049 0.0057 0.0052

0.0016 0.0046

a

Average absolute deviation in temperature. bAverage absolute deviation in vapor-phase composition. cMolar liquid volumes of pure components from ref 9. dTernary prediction from binary parameters. eVolume and surface parameters from ref 18. fCalculation based on UNIFAC.14

N,N-dimethylacetamide (3) + 2-propanol (2) and the ternary system 2-isopropoxypropane (1) + 2-propanol (2) + N,Ndimethylacetamide (3) at 101.3 kPa. All of these binary systems could be correlated with the UNIFAC, UNIQUAC, NRTL, and Wilson models, and the ternary system could yield reasonable predictions from the binary systems. From the experimental results, N,N-dimethylacetamide improves the relative volatility of 2-isopropoxypropane to 2-propanol. The relative volatility (αS12 = 4.6) confirms that N,N-dimethylacetamide is a outstanding solvent to break the azeotropic mixture (2-isopropoxypropane + 2-propanol).

parameters, respectively, A, B, and C are the ternary parameters, and all of these parameters are listed in Table 9, with information indicating the quality of the correlation. In Figure 7 the residue curve, at 101.3 kPa, is simulated by Aspen plus. It used the UNIFAC model. As can be seen from the residue

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AUTHOR INFORMATION

Corresponding Author

*Fax: 86-24-89383736. E-mail: [email protected]. Funding

The authors acknowledge to the National Science Foundation of China (Project No. 21076126) and Program for Liaoning Excellent Talents in University (Project No. 2012013) for partial financial support of this project. Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Arce, A.; Arce, A. J.; Martínez-Ageitos, J.; Rodil, E.; Rodríguez, O.; Soto, A. Physical and equilibrium properties of diisopropyl ether + isopropyl alcohol + water system. Fluid Phase Equilib. 2000, 170, 113− 126. (2) Kim, D. H.; Kim, Y. D. Electrorheological properties of polypyrrole and its composite ER fluids. J. Ind. Eng. Chem. 2007, 13, 879. (3) Lladosa, E.; Montón, J. B.; Burguet, M.; Muñoz, R. Effect of pressure and the capability of 2-methoxyethanol as solvent in the behavior of 2-Isopropoxypropane - 2-propanol azeotropic mixture. Fluid Phase Equilib. 2007, 210, 271−279. (4) Walas, S. M. Phase equilibria in chemical engineering; Butterworth: Boston, 1985. (5) Doherty, M. F.; Malone, M. F. Conceptual Design of Distillation Systems; McGraw-Hill: New York, 2001. (6) Marcus, Y. The properties of solvents; Wiley: Ann Arbor, 1998.

Figure 7. Residual curve map for the ternary 2-isopropoxypropane (1) + 2-propanol (2) + N,N-dimethylacetamide (3).

curve map, all residue curves trending the N,N-dimethylacetamide vertex are inflected toward the N,N-dimethylacetamide-2-propanol face with the result that 2-propanol and N,N-dimethylacetamide will be recovered in the bottom and 2-isopropoxypropane in the distillate, it can be expected from the behavior of binary systems.

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CONCLUSIONS Consistent VLE data have been reported for the binary systems N,N-dimethylacetamide (3) + 2-isopropoxypropane (1) and 362

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(7) Hunsmann, W. Verdampfungsgleichgewicht von Ameisensäure/ Essigsäure-und von Tetrachlorko hlenstoff/Perchloräthylen-Gemischen. Chem. Ing. Tech. 1967, 39, 1142−1145. (8) Rowley, R. L.; Widling, W. V.; Marshall, T. L.; Daubert, T. E.; Danner, R. P.; Adams, M. E. Physical and Thermodynamic Properties of Pure Chemicals; Taylor & Francis: Bristol, 1989. (9) CHEMCAD Software, Version 5.1; Chemstations Inc.: Houston, 2001. (10) Soave, G. Equilibrium constants from a modified Redlich-Kwong equation of state. Chem. Eng. Sci. 1972, 27, 1197−1203. (11) Fredenslund, A.; Gmehling, J.; Rasmussen, P. Vapor-liquid equilibria using UNIFAC: a group contribution method; Elsevier: Amsterdam, 1977. (12) Wilson, G. M. A New Expression for the Excess Free Energy of Mixing. J. Am. Chem. Soc. 1964, 86, 127−130. (13) Renon, H.; Prausnitz, J. M. Local compositions in thermodynamic excess functions for liquid mixtures. AIChE J. 1968, 14, 135−144. (14) Gmehling, J.; Li, J.; Schiller, M. Present parameter matrix and results for different thermodynamic properties. Ind. Eng. Chem. Res. 1993, 32, 178−193. (15) Wisniak, J.; Tamir, A. Correlation of the boiling points of mixtures. Chem. Eng. Sci. 1976, 8, 631−635. (16) McDermott, C.; Ellis, S. R. M. A multicomponent consistency test. Chem. Eng. Sci. 1965, 4, 293−296. (17) Wisniak, J. A new test for the thermodynamic consistency of vapor-liquid equilibrium. Ind. Eng. Chem. Res. 1993, 7, 1531−1533. (18) Gmehling, J.; Onken, U. Vapor-Liquid Equilibrium Data Collection; DECHEMA: Frankfurt, 1977.

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