Article pubs.acs.org/jced
Isobaric Vapor Liquid Equilibrium Data of Acrylonitrile (1) + Heptan-1-ol (2), Acrylonitrile (1) + Ethanol (2), and Nitrobenzene (1) + Heptan-1-ol (2) at 96.5 kPa Pradeep Kumar Mamidipelli* and Shuwana Tasleem Properties Evaluation Group, Chemical Engineering Division, Indian Institute of Chemical Technology, Hyderabad 500007, India ABSTRACT: Isobaric phase equilibrium studies on the binary systems comprising acrylonitrile (1) + heptan-1-ol (2), acrylonitrile (1) + ethanol (2), and heptan-1-ol (1) + nitrobenzene at 96.5 kPa are reported. The activity coefficients are modeled using Wilson’s method and the UNIFAC group contribution method.
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INTRODUCTION The mixtures of acrylonitrile (CAS RN: 107-13-1) with ethanol (CAS RN: 64-17-5) and heptan-1-ol (CAS RN: 111-70-6) are found in the preparation of the various acrylonitrile products such as polyacrylonitrile and other synthetic rubbers, where acrylonitrile is a raw material and ethanol and/or heptanol are used as solvent. The mixture of nitrobenzene (CAS RN: 98-95-3) and heptan-1-ol are obtained in the processes preparing different paint solvents. The recovery of solvent and/or the unreacted raw material calls for the separation of these mixtures. The appreciable difference in boiling points suggests distillation as a potential separation process. However, the proper design of the unit requires vapor−liquid data. The VLE data pertaining to the systems acrylonitrile (1) + heptan-1-ol (2), acrylonitrile (1) + ethanol (2), and nitrobenzene (1) + heptan-1-ol (2) are not available in the literature published so far. Therefore, experiments were performed to study the VLE characteristics of these systems. The experimental data was then modeled using Wilson’s equation and the UNIFAC group contribution method, and the modified Herington’s test was used to check for the thermodynamic consistency.
Table 1. Sample Information source
mole fraction purity
purification method
analysis method
acrylonitrile heptan-1-ol ethanol nitrobenzene
SD Chemicals SD Chemicals SD Chemicals SD Chemicals
0.997 0.996 0.998 0.995
none none none none
GCa GCa GCa GCa
a
Gas chromatography.
refractive index, nD. The measurement were carried out at a temperature of 293.15 K. Good agreement was found between the measured values and literature values1 and is shown in Table 2. Table 2. Experimental and Literature Values of Density, ρ, and Refractive Index, nD, of Pure Compounds at 293.15 K and 96.5 kPa ρa/kg·m−3
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EXPERIMENTAL SECTION Chemicals Used. The chemicals used in the present study, acrylonitrile, ethanol, heptan-1-ol, and nitrobenzene, were purchased from SD chemicals Ltd., India. The purities of the reagents was checked by gas chromatography and found to be more than 0.995 mol fraction. The reagents are used for all experiments without further purification. The uncertainty of the mass fraction was estimated to be within ± 0.001. The sample information is tabulated in Table 1. Experimental Apparatus. The physical properties, namely, the density and refractive index are measured for the pure components. Density, ρ, was measured by a DMA-4100 densimeter, with an uncertainty of ± 0.0001 g·cm−3. A WZS-I Abbe refractometer (Shanghai Optical Instruments Factory, China) with an uncertainty of ± 0.0001 was used to measure the © 2013 American Chemical Society
chemical name
nDa
component name
expt
literature1
expt
literature1
acrylonitrile nitrobenzene ethanol heptan-1-ol
806.0 1198.8 788.9 803.4
805.9 1199.0 789.1 803.5
1.3909 1.5529 1.3610 1.3851
1.3911 1.5530 1.3611 1.3850
a
The experimental values are reported at a temperature of 293.15 K. u(ρ) = ± 0.0001 g·cm−3, u(nD) = ± 0.0001
VLE experiments were carried out in a Sweitoslawski type ebulliometer, constructed as per the description of Hala.2 A calibrated mercury thermometer (accurate to ± 0.5 K) and calibrated mercury manometer (accuracy of ± 0.133 kPa) are connected to the ebulliometer to measure the temperature and pressure, respectively. Received: March 4, 2013 Accepted: July 31, 2013 Published: August 20, 2013 2420
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Table 3. Physical Properties of Pure Components9 constants
heptan-1-ol
nitrobenzene
acrylonitrile
ethanol
molecular wt Tc (K) Pc (atm) Vc (cm3·g·mol−1) accentric factor (ω) compressibility factor (z) Antoine’s constants
116.2 633 30 433 0.399 0.25 15.306 2626.42 −146.6
123.06 756.0 43.40 334 0.589 0.234 16.387 4022.39 −71.37
53.064 536.0 45.0 210.0 0.35 0.21 15.9253 2782.21 −51.15
46.1 516.2 63 167 0.635 0.248 18.9119 3803.98 −41.68
A B C
Experimental Procedure. The study mixture was prepared gravimetrically, stirred well, charged to the ebulliometer, and heated by gradually increasing the heat supply. The temperature versus time data was recorded. The equilibrium state was observed by constancy of boiling temperature and confirmed by the drop count of 30 per minute. The steady state was ascertained by observing this state for 30 min. At this steady state, the temperature was noted and the samples withdrawn and analyzed. Agilent Gas Chromatography analyzer, model 7890A. The schematic of the experimental setup and the procedure is given in detail in our previous publication.3
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Figure 2. Plot of experimental vapor phase mole fraction, y1, versus experimental liquid phase mole fraction, x1, for the system acrylonitrile (1) + ethanol (2) at 96.5 kPa. × , experimental; −, using the Wilson equation; ---, using the UNIFAC method.
RESULTS AND DISCUSSION The experimental data, bubble temperatures, T, versus the liquid phase composition, x1, and vapor phase composition, y1, are tabulated for all systems namely, acrylonitrile (1) + heptanol (2), acrylonitrile (1) + ethanol (2), and heptanol (1) + nitrobenzene (2) in Tables 5−7. Tables 5−7 also give the calculated values of the liquid phase activity coefficients, γ1 and γ2, and the vapor phase mole fraction, y1; the Wilson4 and UNIFAC5 models are used for calculating the activity coefficients and the vapor phase mole fraction. The optimum values for the Wilson’s parameters are obtained by minimizing the objective function, ϕ, using the Nelder−Mead Table 4. UNIFAC Group Specifications5 group numbers main
secondary
name
volume, Rk
surface area, Qk
1 1 1 3 5 27 36
1 2 3 10 15 58 69
CH3 CH2 CH ACH OH ACNO2 ACRY
0.9011 0.6744 0.4469 0.5313 1 1.4199 2.3144
0.848 0.540 0.228 0.4 1.2 1.104 2.052
Figure 3. Plot of experimental vapor phase mole fraction, y1, versus experimental liquid phase mole fraction, x1, for the system heptan-1-ol (1) + nitrobenzene (2) at 96.5 kPa. × , experimental; −, using the Wilson equation; ---, using the UNIFAC method.
Figure 4. Plot of temperature versus composition for the system acrylonitrile (1) + heptan-1-ol (2). •, measured T−x1 data; ⧫, measured T−y1; −−, T−y1 computed from the Wilson model.
optimization technique described by Kuester and Mize.8 The objective function, ϕ, is defined as
Figure 1. Plot of experimental vapor phase mole fraction, y1, versus experimental liquid phase mole fraction, x1, for the system acrylonitrile (1) + heptan-1-ol (2) at 96.5 kPa. ×, experimental; −, using the Wilson equation; ---, using the UNIFAC method.
ϕ= 2421
∑ [(PCal/PExptl) − 1]2
(1)
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Table 5. Experimental VLE Data for Temperature, T, Pressure, p = 96.5 kPa, Liquid-Phase Mole Fraction, x, and Vapor-Phase Mole Fraction, y, Calculated Activity Coefficients, γ, Vapor-Phase Mole Fraction, yc, and Excess Gibbs Free Energy, gE, for the Binary System Acrylonitrile (1) + Heptan-1-ol (2)a calculated by Wilson
a
calculated by UNIFAC
T/K
x1
y1
γ1
γ2
Δy1
γ1
γ2
Δy1
gE/kJ·kmol−1
449.15 422.15 407.15 390.65 384.65 381.15 376.65 373.15 369.15 367.15 363.65 361.15 359.15 353.15 351.65 350.15
0.000 0.100 0.180 0.301 0.361 0.400 0.457 0.505 0.564 0.603 0.672 0.714 0.766 0.923 0.966 1.0000
0.000 0.733 0.865 0.938 0.955 0.962 0.971 0.975 0.981 0.984 0.987 0.989 0.991 0.996 0.999 1
1.778 1.739 1.681 1.567 1.506 1.465 1.406 1.356 1.297 1.259 1.195 1.158 1.116 1.018 1.004 1.000
1.000 1.004 1.013 1.045 1.071 1.093 1.133 1.176 1.245 1.303 1.438 1.550 1.732 2.993 3.830 4.921
0.000 0.001 −0.002 −0.002 −0.001 −0.002 −0.001 −0.002 0 0 0 0 0 0 0.001 0
2.089 1.772 1.659 1.494 1.409 1.362 1.295 1.247 1.189 1.158 1.111 1.082 1.054 1.004 1.001 1.000
1.000 1.003 1.014 1.050 1.082 1.106 1.152 1.195 1.264 1.314 1.418 1.502 1.625 2.174 2.373 2.843
0.000 −0.002 0 0.001 0.002 0.002 0.002 0.001 0.001 0.002 0.001 0 0 −0.001 0 0
0.00 205.58 353.45 540.53 613.20 653.08 699.46 726.69 743.84 744.37 721.87 691.81 635.14 296.69 145.00 0.00
Wilson parameters: [(λ12 − λ11)/R] = 247.3; [(λ12 − λ11)/R] = 310.8; standard deviation = 0.11 K. u(T) = 1 K, u(p) = ± 0.133 kPa, and u(x1) = u(y1) = 0.005.
Table 6. Experimental VLE Data for Temperature, T, Pressure, p = 96.5 kPa, Liquid-Phase Mole Fraction, x, Vapor-Phase Mole Fraction, y, Calculated Activity Coefficients, γ, Vapor-Phase Mole Fraction, yc, and Excess Gibbs Free Energy, gE, for the Binary System Acrylonitrile (1) + Ethanol (2)a calculated by Wilson
a
calculated by UNIFAC
T/K
x1
y1
γ1
γ2
Δy1
γ1
γ2
Δy1
gE/kJ·kmol−1
351.15 349.15 347.15 346.15 345.15 344.65 344.65 344.15 344.15 343.65 343.65 343.65 343.65 344.15 344.15 344.65 345.15 346.15 347.65 348.65 350.15
0.000 0.052 0.129 0.187 0.229 0.283 0.301 0.356 0.419 0.481 0.526 0.564 0.624 0.661 0.700 0.753 0.811 0.875 0.932 0.967 1.0000
0.000 0.126 0.254 0.321 0.361 0.401 0.415 0.449 0.488 0.520 0.541 0.563 0.589 0.607 0.633 0.667 0.710 0.774 0.851 0.919 1
2.719 2.469 2.161 1.968 1.848 1.710 1.669 1.553 1.439 1.345 1.286 1.240 1.178 1.145 1.114 1.078 1.046 1.021 1.006 1.002 1.000
1.000 1.003 1.016 1.035 1.052 1.081 1.092 1.132 1.187 1.256 1.314 1.372 1.479 1.556 1.650 1.799 2.000 2.280 2.597 2.834 3.090
0 0.002 0.002 0 −0.001 −0.005 −0.003 −0.006 −0.002 −0.003 −0.004 0 −0.004 −0.005 −0.001 0 0 0.002 0.001 0.003 0
2.753 2.646 2.219 1.985 1.839 1.685 1.638 1.514 1.395 1.302 1.249 1.207 1.149 1.120 1.094 1.063 1.036 1.018 1.005 1.002 1.000
1.000 1.003 1.020 1.042 1.064 1.096 1.109 1.153 1.214 1.285 1.341 1.396 1.500 1.572 1.652 1.782 1.955 2.149 2.419 2.568 2.773
0 −0.006 −0.002 0 0.003 0.002 0.005 0.005 0.011 0.011 0.008 0.011 0.005 0.003 0.003 0.002 −0.002 −0.008 −0.007 −0.004 0
0.00 143.80 327.45 444.32 516.38 595.54 617.66 676.29 722.15 745.07 748.06 741.33 713.25 685.19 645.87 577.77 481.36 348.37 204.57 103.91 0.00
Wilson parameters: [(λ12 − λ11)/R] = 94.3; [(λ12 − λ11)/R] = 334.5; standard deviation = 0.17 K. u(T) = 1 K, u(p) = ± 0.133 kPa, and u(x1) = u(y1) = 0.005.
The activity coefficient values, thus calculated, are then used to find the corresponding vapor phase mole fraction, yi from the relation
The liquid molar volume for each pure species is computed using the modified Rackett equation as given by Spencer and Danner.6 The crtical compressibility factor is evaluated using the method proposed bye Yamada and Gunn.7 The saturated vapor pressures are calculated using the Antoine’s equation given as ln(Pi sat /mmHg) = Ai − Bi /[(T /K + Ci]
ϕi yP = γi x iPi sat i exptl
(2)
(3)
Where
The Antoine constants (A, B, and C) are obtained from the literature9 and are given in Table 3.
ϕi = ϕ∧ i /ϕisexp[−v iL(PExptl − Pi sat )/RT] 2422
(4)
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Table 7. Experimental VLE Data for Temperature, T, Pressure, p = 96.5 kPa, Liquid-Phase Mole Fraction, x, Vapor-Phase Mole Fraction, y, Calculated Activity Coefficients, γ, Vapor-Phase Mole Fraction, yc, and Excess Gibbs Free Energy, gE, for the Binary System Heptan-1-ol (1) + Nitrobenzene (2)a calculated by Wilson
calculated by UNIFAC
T/K
x1
y1
γ1
γ2
Δy1
γ1
γ2
Δy1
gE/kJ·kmol−1
483.15 470.15 461.15 458.15 455.65 454.15 453.15 452.65 451.65 451.15 450.65 450.15 449.65 449.15 448.65 448.15 448.15 448.15 448.65 448.65 449.15
0.000 0.041 0.099 0.138 0.189 0.234 0.287 0.316 0.372 0.411 0.480 0.521 0.573 0.610 0.680 0.740 0.796 0.844 0.918 0.977 1.0000
0.000 0.304 0.470 0.526 0.571 0.600 0.624 0.640 0.658 0.669 0.686 0.700 0.715 0.726 0.757 0.776 0.806 0.844 0.894 0.964 1
4.952 4.228 3.407 2.987 2.561 2.271 2.003 1.882 1.690 1.580 1.423 1.347 1.267 1.219 1.143 1.093 1.057 1.033 1.009 1.001 1.000
1.000 1.004 1.022 1.041 1.074 1.110 1.161 1.193 1.263 1.320 1.437 1.518 1.636 1.732 1.946 2.173 2.429 2.693 3.205 3.744 3.989
0 0 −0.001 −0.002 −0.003 −0.003 −0.004 0.001 0 −0.001 −0.003 −0.001 −0.001 −0.001 0.005 0 0.002 0.01 −0.001 −0.001 0
4.857 4.201 3.325 2.927 2.486 2.179 1.908 1.793 1.602 1.493 1.349 1.285 1.211 1.169 1.109 1.066 1.038 1.020 1.006 1.002 1.000
1.000 1.004 1.023 1.041 1.077 1.116 1.170 1.203 1.276 1.336 1.450 1.527 1.636 1.728 1.900 2.089 2.288 2.476 2.737 2.892 3.157
0 0.001 0.005 0.003 0.004 0.008 0.01 0.014 0.015 0.015 0.01 0.011 0.008 0.006 0.007 −0.003 −0.005 0 −0.015 −0.009 0
0.00 246.08 540.78 708.04 893.03 1026.96 1152.18 1206.49 1284.24 1318.26 1339.72 1329.44 1292.60 1250.28 1134.51 997.94 839.52 679.50 388.22 116.00 0.00
a Wilson parameters: [(λ12 − λ11)/R] = 417.7; [(λ12 − λ11)/R] = 430.6; standard deviation = 0.09 K. u(T) = 1 K, u(p) = ± 0.133 kPa, and u(x1) = u(y1) = 0.005.
Table 8. Result of the Herington’s Area Test system
Herington’s test (D-J)
acrylonitrile (1) + heptanol (2) acrylonitrile (1) + ethanol (2) heptanol (1) + nitrobenzene (2)
5.8770 0.4153 7.2671
Therefore, for low pressure VLE data eq 3 reduces to yP = γixiPi sat i exptl
(5)
UNIFAC model is very well developed group contribution method explained in detail by Poling et al.5 The parameters (Rk, Qk, and amn) corresponding to the systems under study are given in Table 4. The excess Gibbs free energy is evaluated using the following Wilson’s relation4
Figure 5. Plot of temperature versus composition for the system acrylonitrile (1) + ethanol (2) ●, measured T−x1 data; ⧫, measured T− y1; −−, T−y1 computed from the Wilson model.
g E /RT = −x1 ln(x1 + Λ12x 2) − x 2 ln(x 2 + Λ 21x1)
(6)
The equilibrium data is shown graphically in Figures 1 to 6. Figures 1−3 show the plot of the equilibrium vapor phase composition, y1, plotted against the liquid phase composition, x1, for system acrylonitrile (1) + heptan-1-ol (2), acrylonitrile (1) + ethanol (2), and heptan-1-ol (1) + nitrobenzene (2) respectively. Figures 4−6 show the corresponding T−x1−y1 diagrams. The results are shown in Tables 5, 6, 7. The binary systems under study deviate very marginally from ideality. Both models used correlate the vapor liquid equilibria satisfactorily for all systems. The calculated values of the vapor phase compositions show good agreement with the experimental values. Figures 5 and 6 suggest that the systems acrylonitrile (1) + ethanol (2) and heptan-1-ol (1) + nitrobenzene (2) form minimum azeotropes. The system acrylonitrile (1) + ethanol (2) has an azeotropic composition (x = y = 0.564) at temperature of
Figure 6. Plot of temperature versus composition for the system heptan1-ol (1) + nitrobenzene (2). ●, measured T−x1 data; ⧫, measured T−y1; −−, T−y1 computed from the Wilson model.
At low pressures, vapor phases usually approximate ideal gases, for ̂ which ϕi = ϕi = 1and the poynting factor also becomes equal to 1. Thus, the vapor phase fugacity coefficient, ϕi equals approximately 1. 2423
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343.65 K, whereas the system heptan-1-ol (1) + nitrobenzene (2) forms Azeotrope at temperature 448.15 K and composition (x = y = 0.844). The data is checked for thermodynamic consistency using the Herington test modified by Wisnaik.10 The test for all binary systems under study proves the data to be thermodynamically consistent. The test results are summarized in Table 8.
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CONCLUSION The VLE data of binary mixtures acrylonitrile (1) + heptan-1-ol (2), acrylonitrile (1) + ethanol (2), and nitrobenzene (1) + heptan-1-ol (2) at studied at 96.5 kPa in a Sweitoslawski type ebulliometer. The experimental results are found to be well represented by Wilson and UNIFAC models. The systems acrylonitrile (1) + ethanol (2) and heptan-1-ol (1) + nitrobenzene (2) form minimum azeotropes.
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AUTHOR INFORMATION
Corresponding Author
*E-mail
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Weast, R. C.; Astle, M. J. CRC Handbook of Data on Organic Compounds; CRC Press: Boca Raton, FL, 1985. (2) Hala, E. Vapor-Liquid Equilibrium; Pergamon Press: New York, 1958. (3) Pradeep Kumar, M.; et al. Isobaric Vapor−Liquid Equilibrium Data for the Binary Mixtures 2-Methyl Propan-2-ol with Tetraethoxysilane and 1-Phenyl Ethanone at 95.5 kPa. J. Chem. Eng. Data 2012, 57 (5), 1520−1524. (4) Wilson, G. Vapor-liquid equilibrium. XI. A New Expression for the Excess Gibbs Energy of Mixing. J. Am. Chem. Soc. 1964, 86, 127−130. (5) Poling, B. E.; Prausnitz, J. M.; O’Connell, J. P. The Properties of Gases and Liquids, 5th ed.; McGraw-Hill: New York, 2001. (6) Spencer, C. F.; Danner, R. P. Improved Equation of Saturated Liquid Density. J. Chem. Eng. Data 1972, 17, 236. (7) Yamada, T.; Gunn, R. D. Saturated Liquid Molar Volumes. The Rackett equation. J. Chem. Eng. Data 1973, 18 (2), 234. (8) Kuester, R. T.; Mize, J. H. Optimization Techniques with Fortran; McGraw-Hill: New York, 1973. (9) Sinnot, R. K. Coulson and Richardson’s Chemical Engineering Series, 3rd ed.; Butterworth-Heinemann publication: London, 2001; Vol. 6. (10) Wisniak, J. The Herington Test for Thermodynamic Consistency. J. Ind. Eng. Chem. Res. 1994, 33 (1), 177−180.
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