Isobaric Vapor Liquid Equilibria for Binary Mixtures of Isoamyl Acetate

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Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Isobaric Vapor Liquid Equilibria for Binary Mixtures of Isoamyl Acetate + Ethyl Acetate at 50 and 100 kPa Cesar A. Sań chez, Andreś A. Herrera, Julio C. Vargas, Ivań D. Gil,* and Gerardo Rodríguez

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Research Group of Chemical and Biochemical Process, Department of Chemical and Environmental Engineering, National University of Colombia, Bogotá Campus, Cra 30 No. 45-03, Ed. 453, Of. 318, Bogotá, Colombia ABSTRACT: In this work new phase equilibria data for the system ethyl acetate + isoamyl acetate at pressures of 50 and 100 kPa are reported. The measures were carried out in the equilibrium apparatus FISCHER LABODEST VLE 602D, which is essentially a dynamic equilibrium cell equipped with a Cottrell recirculation pump. The quality of the experimental information was examined with the Wisniak point criteria because binary mixtures under study offer small deviations from the ideality. The nonrandom two-liquid and universal quasichemical activity models with symmetrical parameters were used to correlate experimental data, and both activity models show good correlation with experiments and can be used in distillation process calculations.

1. INTRODUCTION Synthesis and design of distillation process for separating acetates mixtures is a problem that can arise in studies on acetates production from alcohols mixtures and acetic acid. A specific case is the direct esterification of fusel oil (FO) (a mixture of linear and branched alcohols) with acetic acid using reactive distillation to produce acetates (pure or mixed).1−3 In this particular case (direct esterification of FO) two binary mixtures of acetates (isobutyl acetate + isoamyl acetate and isobutyl acetate + ethyl acetate) were considered for Sánchez et al.,3 who concluded from experimental activity coefficients analysis that vapor−liquid equilibrium (VLE) in binary mixtures of acetates (low and medium molecular weights) can be reasonably predicted using the UNIFAC-DMD (modified Raoult’s law) model or even the Ideal Model (Raoult’s law). Binary mixtures of ethyl acetate (EtAc) + isoamyl acetate (iAmAc) are important in the context of direct esterification of fusel oil because ethanol and isoamyl alcohol are always present as part of the fusel oil composition. In fact, a simplified representation, for conceptual design purposes, is that FO is a mixture of water (16 wt %), ethanol (24 wt %), and isoamyl alcohol (40 wt %).4 Then, a simultaneous reaction with acetic acid in a reactive distillation process results in a system that contains EtAc and iAmAc. There is only one report of VLE measurements for this system: isobaric VLE data at 101.325 kPa measured by Savescu et al.5 Taking into account the previous observations (there are few isobaric VLE data available and the relative importance of the binary mixtures of EtAc + iAmAc), and considering that isobaric VLE data for binary mixtures constitute the minimum required information to calculate the adjustable binary interactions parameters for some local-composition model (e.g., nonrandom two-liquid (NRTL), universal quasichemical (UNIQUAC), etc.) useful in distillation calculations, this work focuses in measuring VLE data for the binary mixture of ethyl © XXXX American Chemical Society

acetate + isoamyl acetate at 50 and 100 kPa. Furthermore, the results obtained here complement the equilibrium data of acetates binary mixtures resulting from fusel oil.

2. EXPERIMENTAL SECTION 2.1. Materials. Chemicals used during experiments are listed in Table 1. The purity reported by the manufacturer was Table 1. Summary of Components Used in Vapor−Liquid Equilibrium Experiments chemical name

source

ethyl acetate isobutyl acetate isoamyl acetate acetone

J.T. Baker Merck KGaA Merck KGaA J.T. Baker

a

initial purity (wt %)

purification method

analysis method

≥99 ≥98

none none

GCa GC

≥99

none

GC

≥99

none

GC

Gas chromatography.

confirmed by gas chromatographic analysis using the area method. Acetone (solvent) and isobutyl acetate (internal standard) were used for the preparation of solutions for chromatography. 2.2. VLE Apparatus and Procedure. Experiments were carried out using the equilibrium apparatus FISCHER LABODEST VLE 602. Technical specifications for this dynamic equilibrium cell were reported in previous works.3,6−8 Accuracy in measurements of temperature and Special Issue: Latin America Received: November 8, 2018 Accepted: April 23, 2019

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DOI: 10.1021/acs.jced.8b01053 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

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Table 2. Experimental Vapor Liquid Equilibrium Data for the System Ethyl Acetate (EtAc) + Isoamyl Acetate at 100 kPaa xEtAc

yEtAc

T/K

γEtAc

1.000 0.936 0.881 0.835 0.798 0.753 0.726 0.693 0.667 0.630 0.597 0.578 0.553 0.519 0.446 0.341 0.306 0.292 0.263 0.245 0.208 0.158 0.146 0.135 0.122 0.083 0.012 0.000

1.000 0.994 0.988 0.982 0.977 0.970 0.965 0.959 0.955 0.943 0.933 0.928 0.923 0.911 0.876 0.801 0.780 0.770 0.743 0.705 0.658 0.562 0.525 0.504 0.485 0.379 0.069 0.000

349.53 350.12 351.42 352.84 354.05 355.01 356.20 357.43 358.33 359.89 361.24 362.30 363.21 364.65 368.66 375.95 378.12 379.19 381.52 383.76 386.24 392.08 393.44 395.29 396.46 401.17 412.30 413.46

1.000 1.047 1.059 1.060 1.062 1.082 1.076 1.078 1.084 1.080 1.083 1.076 1.089 1.096 1.092 1.062 1.087 1.092 1.100 1.056 1.089 1.057 1.037 1.031 1.063 1.093 1.072

γiAmAc

ΔγEtAc/γEtAc

ΔγiAmAcγiAmAc

Di (%)

0.930 0.928 0.944 0.903 0.947 0.927 0.934 0.902 0.964 0.981 0.971 0.936 0.956 0.986 1.016 0.986 0.973 0.962 0.997 1.013 1.005 1.028 0.998 0.986 0.983 0.986 1.000

0.015 0.016 0.016 0.017 0.017 0.018 0.018 0.019 0.019 0.020 0.021 0.021 0.022 0.025 0.032 0.035 0.037 0.040 0.043 0.050 0.066 0.071 0.077 0.085 0.123 0.846

1.605 0.813 0.544 0.441 0.331 0.290 0.243 0.224 0.178 0.152 0.140 0.133 0.114 0.083 0.053 0.048 0.046 0.041 0.037 0.032 0.026 0.024 0.023 0.023 0.020 0.015

3.245 3.591 3.785 3.853 3.738 3.799 3.785 3.746 3.721 3.662 3.667 3.590 3.502 3.343 3.097 2.940 2.888 2.776 2.769 2.527 2.366 2.301 2.325 2.218 1.970 2.326

Given are the temperature T, liquid-phase mole fraction x, vapor-phase mole fraction y, calculated results for activity coefficient γ, uncertainty Δγ/ γ, and the consistency parameter Di. Standard uncertainties u are u(T) = 0.1 K, u(P) = 0.14 kPa and u(x) = u(y) = 0.01.

a

Table 3. Experimental Vapor Liquid Equilibrium Data for the System Ethyl Acetate (EtAc) + Isoamyl Acetate at 50 kPaa xEtAc

yEtAc

T/K

γEtAc

1.000 0.954 0.929 0.894 0.823 0.775 0.737 0.632 0.516 0.470 0.418 0.370 0.322 0.299 0.263 0.239 0.206 0.181 0.139 0.101 0.016 0.000

1.000 0.997 0.995 0.992 0.986 0.978 0.974 0.959 0.922 0.891 0.873 0.852 0.819 0.797 0.762 0.741 0.699 0.647 0.564 0.430 0.104 0.000

330.01 330.69 330.99 331.85 333.55 334.85 336.13 339.59 344.37 346.68 349.41 351.38 354.46 356.77 359.43 361.57 364.26 366.87 370.84 375.99 388.47 391.07

1.000 1.034 1.047 1.050 1.062 1.066 1.064 1.077 1.071 1.049 1.054 1.089 1.089 1.060 1.060 1.063 1.072 1.046 1.058 0.962 1.057

γiAmAc

ΔγEtAc/γEtAc

ΔγiAmAcγiAmAc

Di (%)

0.784 0.833 0.854 0.821 0.950 0.902 0.858 0.990 1.137 1.067 1.053 1.047 1.030 1.029 0.994 0.994 1.020 1.029 1.065 0.991 1.000

0.015 0.015 0.016 0.016 0.017 0.018 0.019 0.023 0.024 0.027 0.030 0.034 0.036 0.040 0.044 0.051 0.057 0.074 0.102 0.632

3.340 2.005 1.254 0.717 0.457 0.387 0.245 0.130 0.094 0.081 0.070 0.057 0.051 0.044 0.041 0.036 0.031 0.026 0.021 0.016

3.506 3.606 3.899 4.038 4.055 4.087 3.953 3.732 3.631 3.484 3.260 3.092 3.058 2.905 2.815 2.643 2.537 2.266 2.109 1.686

Given are the temperature T, liquid-phase mole fraction x, vapor-phase mole fraction y, calculated results for activity coefficient γ, uncertainty Δγ/ γ, and the consistency parameter Di. Standard uncertainties u are u(T) = 0.1 K, u(P) = 0.14 kPa and u(x) = u(y) = 0.01.

a

B



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pressure (certified by the manufacturer) are ±0.01 K and 0.01 kPa, respectively. The operational procedure is also described in previous works,3,6−8 but will be written here anew to contextualize the nature of experiments from this work. At the beginning of the tests, the mixed chamber and the side reservoir are loaded with the pure components; therefore, depending on the requirements, different binary solutions are prepared by the regulated addition of the component in the side reservoir. In each experimental run, the pressure is controlled in a fixed value and the system is operated at total reflux under continuous agitation. The heating supply is adapted so that the reflux flow of the vapor phase is 1−2 drops per second. It is considered that the system is in VLE when temperature variations are less than 0.1 K for at least 30 min. Statistical control charts are used to calculate (in real time) the variations on the temperature and pressure measurements. After equilibrium conditions are established, samples of liquid and condensed vapor are taken for chromatography analysis. 2.3. Analysis. Analysis of samples were carried out by gas chromatography using a Shimadzu 2010 GC equipped with an automatic injector, a SGE column (BP20, 30 m−530 μm; i.d., 0.5 μm) and a flame ionization detector (FID). The operating conditions for the chromatograph were the same that Sánchez et al.3 used to analyze mixtures of isobutyl acetate + isoamyl acetate. The solutions for chromatography are prepared by mixing 100 mg of sample, 60 mg of isobutyl acetate (internal standard), and 700 mg of acetone (solvent). The uncertainty in the concentration measurements was determined by analyzing solutions with specified composition, using the calibration curves of the chromatographic technique for this purpose. A maximum average error of 0.01 in the mole fraction of each component was calculated.

Then, according with eq 2, and applying the concept of experimental error propagation,14 the absolute error (i.e., uncertainty) for the activity coefficient of component i, is as follows: ÅÄÅ ÅÅij Δy yz2 i Δx y2 i ΔP y2 j z 2 2Å zzz (Δγi) = γi ÅÅÅjjjj i zzzz + jjj− i zzz + jjj j xi z ÅÅj y z k P { ÅÅÇk i { k { É 2Ñ ij d ln(psat ) yz ÑÑÑÑ i + jjjj− (ΔT )zzzz ÑÑÑ j z ÑÑÑ dT k { ÑÖ (3) The uncertainties of the independent variables (x, y, T, and P) were approximated as follows: for the mole fraction, the uncertainty was considered as the maximum error associated with the chromatography (Δx = Δy = 0.01); for the temperature and pressure, the uncertainty was assumed as the maximum allowable variation in the equilibrium conditions (ΔT = 0.1 K; ΔP = 0.1 kPa). Antoine equation parameters were taken from Sánchez et al.3 It is important to note that relative uncertainties (Δγi/γi) are very high when xi (or yi) approaches to zero according to the dependency on the mole fraction in eq 3. Therefore, the activity coefficients at infinite dilution calculated with this method are accompanied in a natural way, by high uncertainties. The results of application of eqs 2 and 3 on experimental data generated in this work for the EtAc + iAmAc system at 100 and 50 kPa are listed in Tables 2 and 3, respectively. Calculated uncertainties, as expected, are especially high at low concentration (mole fraction less than 0.1). The activity coefficient for EtAc is nearly constant and very close to unity (except at low concentration). The activity coefficient for iAmAc presents a greater variation, however, for uncertainties less than 10%, it can also be considered nearly constant. The thermodynamic consistency of experimental data was evaluated by using the Wisniak point method.9,10 This method was selected considering the nearly ideal behavior of the systems under study. In the Wisniak method, consistency is expressed by eq 4 and the practical criteria is provided by the variable Di in eq 5. The test is approved when values of Di are less than 5%.

3. RESULTS AND DISCUSSION The experimental results of VLE (T−x−y data) are presented in Tables 2 and 3. In this section, two subjects are described: (1) calculation, consistency, and uncertainty of the experimental activity coefficients (section 3.1), (2) model parameters regression (section 3.2). From a general viewpoint it was found that (1) all experimental VLE points are consistent according to the Wisniak Test9,10 and (2) the nonrandom two-liquid (NRTL)11 or the universal quasichemical (UNIQUAC)12 models with a symmetrical parameter can fit experimental results. 3.1. Experimental Activity Coefficients: Uncertainty and Consistency. The activity coefficient can be calculated from the gamma-phi formulation of the VLE:13 ÑÉÑ ÅÄÅ p Å 1 l Ñ ÑÑ v d p yi φiP = xiγipisat φisat expÅÅÅÅ Ñ ∫ ÅÅÅ RT pisat i ÑÑÑÑ (1) Ö Ç Here the Poynting factor can be approximated as the unity, because this term is important only at high pressures.13 Additionally, the low pressure used in this work (100 kPa) and the similar physicochemical nature of the substances employed also allow consideration of the vapor phase as an ideal gas. With these considerations eq 1 results in the modified Raoult’s law,13 and with the use of the experimental equilibrium data, the activity coefficient can be calculated with eq 2: yP γi = i sat xipi (2)

Li =

gE 1 RTw = Wi ∑ xiΔsi,vapTisat − T = − Δs i Δs Δs

Di = 100

|Li − Wi | ≤5 Li + Wi

(4)

(5)

The different terms in eq 4 are interpreted as follows: eq 6 is a basic thermodynamic relation between activity coefficients and the excess Gibbs free energy and eq 7 is the entropy of vaporization for the i component. Equations 8 and 9 are convenient grouping variables. The Clausius−Clapeyron13 equation was considered a good approximation to estimate the enthalpy of vaporization at experimental conditions. The values of the consistency parameter Di in eq 5 are listed in Tables 2 and 3. As observed, all reported experimental points fulfill the Wisniak’s test. gE = RT C

∑ xi ln(γi) i

(6) DOI: 10.1021/acs.jced.8b01053 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data Δsi,vap = Δs =

Δhi ,vap Tisat

(7)

∑ xiΔsi,vap

(8)

i yi yz zz zz k xi {

i

w=

Article

∑ xi lnjjjjj i

(9)

3.2. Calculation of Binary Parameters for the Activity Models. The regression tool available in Aspen Plus V9 was used to fit the binary parameters in the UNIQUAC12 and NRTL11 activity models. Standard equations, temperature dependent, were used in the calculations. Equations 10 and 11 correspond, respectively, with the relations for the parameters in the UNIQUAC and NRTL models. It was considered sufficient with only a fitting parameter, because mixtures under consideration deviate slightly of ideality. Symmetrical parameters temperature dependent were selected with ai,j = aj,i = 0 and bi,j = bj,i. The activity models chosen to obey the need of unifying the thermodynamic models used for process design; in the case of the direct esterification of fusel oil available, experimental data are correlated with UNIQUAC and NRTL models.2,3 τi , j = ai , j +

Figure 1. T−x−y diagram for the system ethyl acetate (EtAc) + isoamyl acetate (iAmAc) at 100 (left) and 50 (righ) kPa. (○) experiment from this work, () fitted with UNIQUAC, (---) calculated with UNIFAC-DMD.

The predicted curves using the NRTL equation model were not included in Figure 1 because, in practice, it is not possible to distinguish these from those generated with UNIQUAC model. This implies, that in practical terms, both models offer similar prediction capacity. According to the obtained results, the regressed models can be confidently integrated in a more complex thermodynamic model to study the direct esterification of the fusel oil. According to Mathias,20 a complementary appreciation of the model qualities can be carried out comparing graphically experimental and predicted K-values. In this way, it is possible to observe quantification of model and data uncertainties “at a glance”. On the other hand, the curves of the logarithm of Kvalue against inverse of temperature are (approximately) straight lines for systems with small deviations from ideality. These two ideas can be observed in Figure 2. According to the figure, predictions for KEtAc correspond very well with experimental data in the entire temperature domain but predictions for KiAmAc deviate appreciably at low temperatures (i.e., dilute solutions of iAmAc in EtAc). These experimental points with the highest deviations correspond with the rows (see Tables 2 and 3) with the highest uncertainties in the activity coefficient. The uncertainty in measured variables (x, y, T, and p) propagates in experimental activity coefficients, and then propagates in K-values. Taking into account eq 3: the uncertainty in the activity coefficient (and then in K-values) can be decreased when the precision in the quantification of x and y increases (i.e., very precise calibration curves). As previously mentioned, there is only one report of VLE measurements for EtAc + iAmAc: isobaric VLE data at 101.325 kPa measured by Savescu et al.5 In Figure 3, experimental VLE data from Savescu et al.5 are contrasted with the predictions of fitted UNIQUAC (with parameters in Table 4) and UNIFACDMD models. It is observed that experimental data from Savescu et al.5 can be described quite well with both models and are consistent with experimental reports in this work. Consequently, fitted models (UNIQUAC and NRTL) and the predictive model UNIFAC-DMD are reliable alternatives to calculate VLE for this binary mixture of acetates. The comparison with Savescu et al.5 data is an extrapolation for

bi , j (10)

T

ij bi , j yz zz τi , j = expjjjai , j + z j T z{ k

(11)

The objective function was the maximum likelihood and was based upon the summation of differences between all measured and predicted variables.15 The convergence algorithm used was the Britt−Luecke16 with a tolerance of 1 × 10−10. Table 4 presents the regressed parameters for the pressure range analyzed, with the corresponding standard deviation. Table 4. Regressed NRTL and UNIQUAC Parameters for the System Ethyl Acetate (1) + Isoamyl Acetate (2) parameter

UNIQUAC

NRTL

b1,2 = b2,1 (K) σa α1,2 = α2,1 ΔTmax (K) Δxmax Δymax

−10.0628 1.4777

21.5525 5.9995 0.30 0.099 −0.029 0.021

0.093 −0.027 0.022

a

Standard deviation for b.

Figure 1 presents the T−x−y diagrams obtained for the system under consideration. From this figure, it is possible to observe the good agreement between the experimental data and the regressed model. A contrast with the predictions of the modified Dortmund UNIFAC model17−19 (UNIFAC-DMD) was also included in the figure. These predictions correspond very well with the experimental data for the dew point curves and deviate slightly for the bubble point curves. The qualitative conclusion is the same from Sánchez et al.,3 who concluded, for isobutyl acetate + isoamyl acetate and isobutyl acetate + ethyl acetate mixtures, that UNIFAC-DMD model can be a good approximation. D



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parameters can be used in calculations related to the separation by the distillation of mixtures of ethyl acetate + isoamyl acetate, or can be coupled with multicomponent NRTL and UNIQUAC equations to investigate the simultaneous esterification of the fusel oil.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Cesar A. Sánchez: 0000-0002-7826-9582 Iván D. Gil: 0000-0002-0638-0222 Notes

The authors declare no competing financial interest.

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REFERENCES

(1) Patidar, P.; Mahajani, S. M. Esterification of Fusel Oil Using Reactive Distillation − Part I: Reaction Kinetics. Chem. Eng. J. 2012, 207−208, 377−387. (2) Patidar, P.; Mahajani, S. M. Esterification of Fusel Oil Using Reactive Distillation. Part II: Process Alternatives. Ind. Eng. Chem. Res. 2013, 52, 16637−16647. (3) Sánchez, C. A.; Sánchez, O. A.; Orjuela, A.; Gil, I. D.; Rodríguez, G. Vapor−Liquid Equilibrium for Binary Mixtures of Acetates in the Direct Esterification of Fusel Oil. J. Chem. Eng. Data 2017, 62, 11−19. (4) Ferreira, M. C.; Meirelles, A. J. A.; Batista, E. A. C. Study of the Fusel Oil Distillation Process. Ind. Eng. Chem. Res. 2013, 52, 2336− 2351. (5) Savescu, V.; Ionescu, I.; Mehedinteanu, L. Isobaric Vapor-Liquid Equilibria for Ethyl Acetate+ Isoamyl Alcohol and Ethyl Acetate+ Isoamyl Acetate Mixtures. Rev. Roum. Chim. 1997, 42, 51−54. (6) Durán, J.; Córdoba, F.; Gil, I.; Rodríguez, G.; Orjuela, A. Vapor− liquid Equilibrium of the Ethanol+3-Methyl-1-Butanol System at 50.66, 101.33 and 151.99 KPa. Fluid Phase Equilib. 2013, 338, 128− 134. (7) Rojas, O.; Salazar, A.; Gil, I.; Rodríguez, G. Effect of Pressure on the Azeotrope of the Mixture Isoamyl Acetate−Isoamyl Alcohol at 50.00, 101.32, 250.00, and 350.00 KPa. J. Chem. Eng. Data 2016, 61, 3109−3115. (8) Leyva, F.; Orjuela, A.; Gil, I.; Vargas, J.; Rodríguez, G. Vapor− liquid Equilibrium of Isoamyl Alcohol+isoamyl Propionate and Propionic Acid+isoamyl Propionate Systems at 50.00, 101.33 and 150.00 kPa. Fluid Phase Equilib. 2013, 356, 56−62. (9) Wisniak, J. A. New Test for the Thermodynamic Consistency of Vapor-Liquid Equilibrium. Ind. Eng. Chem. Res. 1993, 32, 1531−1533. (10) Wisniak, J.; Apelblat, A.; Segura, H. An Assessment of Thermodynamic Consistency Tests for Vapor-Liquid Equilibrium Data. Phys. Chem. Liq. 1997, 35, 1−58. (11) Renon, H.; Prausnitz, J. M. Local Compositions in Thermodynamic Excess Functions for Liquid Mixtures. AIChE J. 1968, 14, 135−144. (12) Abrams, D. S.; Prausnitz, J. M. Statistical Thermodynamics of Liquid Mixtures: A New Expression for the Excess Gibbs Energy of Partly or Completely Miscible Systems. AIChE J. 1975, 21, 116−128. (13) Smith, J. M.; Ness, H. Van.; Abbott, M. M. Introduction to Chemical Engineering Thermodynamics; McGraw-Hill Education: 2005. (14) Andraos, J. On the Propagation of Statistical Errors for a Function of Several Variables. J. Chem. Educ. 1996, 73, 150. (15) Bunch, D. S.; Gay, D. M.; Welsch, R. E. Algorithm 717; Subroutines for Maximum Likelihood and Quasi-Likelihood Estimation of Parameters in Nonlinear Regression Models. ACM Trans. Math. Softw. 1993, 19, 109−130. (16) Britt, H. I.; Luecke, R. H. The Estimation of Parameters in Nonlinear, Implicit Models. Technometrics 1973, 15, 233−247. (17) Weidlich, U.; Gmehling, J. A Modified UNIFAC Model. 1. Prediction of VLE, hE, and γ ∞. Ind. Eng. Chem. Res. 1987, 26, 1372− 1381.

Figure 2. Vapor−liquid equilibrium ratio (K value) temperature dependence at 50 and 100 kPa in the system ethyl acetate (EtAc) + isoamyl acetate (iAmAc). (○) experiment KEtAc from this work, (□) experiment KiAmAc from this work, () fitted with UNIQUAC, (---) calculated with UNIFAC-DMD. The figure also shows (dotted lines) ± 5% deviations from the calculated K value.

Figure 3. T−x−y diagram (left) and vapor−liquid equilibrium ratio (K value) temperature dependence (right) for the system ethyl acetate (EtAc) + isoamyl acetate (iAmAc) at 101.325 kPa. Experimental data from Savescu et al.5 (○) experiment VLE, (□) experiment KiAmAc, (△) experiment KEtAc, (---) calculated with UNIFAC-DMD, () calculated with UNIQUAC and parameters in Table 4. The figure also shows (dotted lines) ± 5% deviations from the calculated K value.

the models defined in Table 4; however, due to low pressure difference (1.325 kPa), predictions are considered accurate.

4. CONCLUSION New isobaric data of vapor liquid equilibrium for the system ethyl acetate + isoamyl acetate at 50 and 100 kPa were measured. Owing to the small deviations from ideality, the quality of the experimental information was evaluated with the Wisniak point test, and all data approved the proof. The NRTL and UNIQUAC activity models with symmetrical parameters were used to correlate experimental observations, and both models successfully describe reported VLE data. Fitted binary E



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(18) Gmehling, J.; Li, J.; Schiller, M. A Modified UNIFAC Model. 2. Present Parameter Matrix and Results for Different Thermodynamic Properties. Ind. Eng. Chem. Res. 1993, 32, 178−193. (19) Jakob, A.; Grensemann, H.; Lohmann, J.; Gmehling, J. Further Development of Modified UNIFAC (Dortmund): Revision and Extension 5. Ind. Eng. Chem. Res. 2006, 45, 7924−7933. (20) Mathias, P. M. Guidelines for the Analysis of Vapor−Liquid Equilibrium Data. J. Chem. Eng. Data 2017, 62, 2231−2233.

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Isobaric Vapor Liquid Equilibria for Binary Mixtures of Isoamyl Acetate

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