Fluid Phase Equilibria 341 (2013) 30–34
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Fluid Phase Equilibria
journal homepage: www.elsevier.com/locate/fluid
Investigation on vapor–liquid equilibrium for
2-propanol + 1-butanol + 1-pentanol at 101.3 kPa
Juan Wang, Zonghong Bao ∗
College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China
a r t i c l e
i n f o
Article history:
Received 26 September 2012
Received in revised form 5 December 2012
Accepted 18 December 2012
Available online 7 January 2013
Keywords:
2-Propanol
1-Butanol
1-Pentanol
Vapor–liquid equilibrium
a b s t r a c t
Isobaric vapor–liquid equilibrium (VLE) data for 2-propanol + 1-butanol, 2-propanol + 1-pentanol, 1butanol + 1-pentanol and 2-propanol + 1-butanol + 1-pentanol were measured at 101.3 kPa by using an
improved Rose still. All the binary VLE data have passed the traditional area test proposed by Herington.
The interaction parameters for the Wilson, NRTL and UNIQUAC equations were determined by regressing the binary VLE data. The prediction for ternary system was given by using the three pairs of binary
parameters correlated. And the ternary data predicted agreed well with the experiment data.
© 2013 Elsevier B.V. All rights reserved.
1. Introduction
Currently the international oil price has been rising, and the
domestic oil resources are increasingly scarce. All these lead to a
trend about producing mixed alcohols by using coal. The C1–C8
mixed alcohols were produced at the same time by a new coal
chemical synthesis technology in a set of device. This production
has already begun to accelerate the domestic industrial process [1].
Mixed alcohols can continue to conduct multi-fractionations
and result in a series of single alcohol include methanol, ethanol,
propanol, etc. But the vapor–liquid equilibrium (VLE) data play
an important role in the design and optimized operations of
distillation processes. So far many useful VLE data among the
mixed alcohols have been presented. However, for 2-propanol + 1pentanol system, there is only one report about VLE data in 313.15 K
[2], and no report is in isobaric condition. To 1-butanol + 1-pentanol
system, data in low pressure are available [3], but they may not
meet the requirement of design calculations. As for 2-propanol + 1butanol system, Wang et al. [4] determined temperature and
liquid phase mole fraction in 101.3 kPa without giving vaporphase mole fraction. Therefore, it is necessary to measure the VLE
data for 2-propanol + 1-butanol, 2-propanol + 1-pentanol, and 1butanol + 1-pentanol at atmospheric pressure condition.
In this paper, isobaric VLE results for binary mixture of
2-propanol + 1-butanol, 2-propanol + 1-pentanol and 1-butanol +
1-pentanol and ternary mixture of 2-propanol + 1-butanol + 1pentanol were obtained at 101.3 kPa. The experimental values were
correlated by the Wilson, NRTL and UNIQUAC equations, in which
the binary parameters were obtained through the maximum likelihood. The quality of the experimental binary values was verified
by the Herington method [5].
2. Experimental
2.1. Chemicals
The physical properties of chemical reagents used are given
in Table 1. Methanol and 1-pentanol were supplied by Shanghai
Lingfeng Chemical Co. Ltd. 2-Propanol and 1-butanol were supplied
by Shanghai Shenbo Chemical Co. Ltd. Methanol and 2-propanol
were used without further purification. 1-Butanol and 1-pentanol
were further purified by distillation in a column. All the reagents
were dried on 0.4 nm molecular sieves and degassed by ultrasound
before use. The purity of chemicals used was checked by the gas
chromatography equipped with a thermal conductivity detector
and a stainless steel column. The refractive indices and normal boiling points were measured by the WYA Abbe refractometer and the
improved Rose still, respectively.
2.2. Apparatus and procedures
∗ Corresponding author. Tel.: +86 025 83587190.
E-mail address: [email protected] (Z. Bao).
0378-3812/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.fluid.2012.12.020
In this study, the VLE data were obtained with a glass recirculation apparatus called improved Rose still described by Zhang et al.
[7]. A mercury thermometer was used to measure the equilibrium
J. Wang, Z. Bao / Fluid Phase Equilibria 341 (2013) 30–34
31
Table 1
Physical properties of experimental materials.
Compound
Purity (mass %)
Methanol
2-Propanol
1-Butanol
1-Pentanol
Water (mass %)
>99.5
>99.7
>99.6
>99.6
nD (298.15 K)
<0.1%
<0.1%
0.1%
0.1%
Tb /K (101.3 kPa)
Experiment
Literature [6]
Experiment
Literature [6]
1.3288
1.3776
1.3995
1.4097
1.3286
1.3775
1.3993
1.4099
337.69
355.50
390.86
411.10
337.66
355.55
390.85
411.15
Note: u(w) = ±0.001, u(nD ) = ±0.0001, u(Tb ) = ±0.01 K.
temperature with an accuracy of temperature of 0.1 K, and conducted exposed neck correction to obtain the true temperature. The
experiment pressure was controlled by a constant pressure system
(a vacuum pump, a U-tube, and a buffer tank), and the precision
was within ±133 Pa.
In the experiments, all the analytical work was carried out by
a gas chromatograph (GC6890, supplied by Shandong Lunan Ruihong instruments company), which was equipped with a flame
ionization detector (FID). The composition of vapor phase and liquid phase was calculated by the area normalization method, which
can accurate to 0.001. The GC column was 30 m long and 0.32 mm
in diameter silica capillary column packed with OV-1701. The carrier gas was high purity nitrogen, and head pressure was 400 kPa.
The injector and detector temperature of column were 473.15 K
and 493.15 K, respectively.
Methanol + 2-propanol system as a checking system was measured first. The VLE data at 101.3 kPa and comparisons to literature
are shown in Fig. 1. The results matched very well with previous
literature and this result gives us a confidence of our instruments
and analysis method.
3. Results and discussion
3.1. VLE model and experiment data
The VLE results of binary system (2-propanol + 1-butanol,
2-propanol + 1-pentanol, and 1-butanol + 1-pentanol) and ternary
system (2-propanol + 1-butanol + 1-pentanol) are shown in
Tables 2 and 3. The activity coefficient of pure component was
calculated by:
p
pyi ϕiv = xi i psat
ϕis exp
i
ViL
RT
(1)
dp
ps
i
Table 2
VLE data for 2-propanol (1) + 1-butanol (2), 2-propanol (1) + 1-pentanol (2), and 1butanol (1) + 1-pentanol (2) system at 101.3 kPa.
T/K
x1
y1
T/K
x1
y1
2-Propanol (1) + 1-butanol (2)
0
390.86
0.0227
389.12
0.0474
387.53
385.95
0.0744
0.1062
384.15
0.1299
382.96
0.1465
381.80
0.2023
379.00
376.05
0.2693
0.3170
374.00
373.65
0.3255
0
0.0672
0.1362
0.2067
0.2825
0.3357
0.3750
0.4759
0.5731
0.6373
0.6480
370.75
369.13
367.77
366.51
364.99
363.60
362.17
360.67
359.27
357.16
355.50
0.4002
0.4471
0.4938
0.5341
0.5840
0.6307
0.6836
0.7333
0.7957
0.9052
1
0.7221
0.7615
0.7954
0.8218
0.8526
0.8768
0.9015
0.9221
0.9448
0.9775
1
2-propanol (1) + 1-pentanol (2)
0
411.10
0.0156
408.68
406.51
0.0315
0.0495
404.91
0.0682
402.10
0.0854
400.42
398.32
0.1016
395.97
0.1250
0.1615
392.48
390.25
0.1895
0.2141
388.14
385.00
0.2579
383.55
0.2794
0
0.0741
0.1499
0.2355
0.2973
0.3565
0.4056
0.4684
0.5509
0.6088
0.6498
0.7155
0.7398
380.36
379.45
377.00
374.75
372.45
371.03
367.88
366.57
363.69
361.67
359.47
357.45
355.50
0.3302
0.3494
0.3956
0.4364
0.4821
0.5105
0.5908
0.628
0.7059
0.7645
0.8324
0.9032
1
0.7905
0.8072
0.8405
0.8644
0.8861
0.8990
0.9275
0.9385
0.9573
0.9685
0.9798
0.9895
1
1-butanol (1) + 1-pentanol (2)
0
411.10
410.00
0.0440
0.0537
409.70
408.00
0.1046
0.1383
407.50
0.1906
406.04
0.2408
404.96
0.2936
404.31
0.3394
403.20
0.3833
401.74
0.4308
400.90
0
0.0741
0.0900
0.1725
0.2245
0.3065
0.3763
0.4378
0.4950
0.5366
0.5875
400.17
398.60
397.88
396.57
395.93
395.13
393.83
393.13
392.02
390.86
0.4836
0.5369
0.5796
0.6488
0.6913
0.7336
0.8022
0.8579
0.9115
1
0.6405
0.6895
0.7297
0.7920
0.8250
0.8604
0.8997
0.9290
0.9599
1
Note: u(T) = ±0.01 K, u(x) = ±0.001, u(y) = ±0.001.
356
354
Table 3
VLE data for 2-propanol (1) + 1-butanol (2) + 1-pentanol (3) ternary system at
101.3 kPa.
352
T/K
350
348
T/K
x1
x2
y1
y2
1
2
3
346
375.71
378.07
381.30
383.30
385.91
388.36
391.37
395.79
397.46
399.49
401.17
403.04
0.3031
0.2648
0.2184
0.1911
0.1595
0.1341
0.1068
0.0428
0.0373
0.0281
0.0216
0.0151
0.6489
0.6172
0.5675
0.5321
0.4855
0.4399
0.3818
0.1755
0.1599
0.1285
0.1036
0.0759
0.5264
0.4775
0.4341
0.4084
0.3722
0.3396
0.3002
0.3980
0.3404
0.2881
0.2429
0.1974
0.3045
0.3047
0.3125
0.3174
0.3189
0.3179
0.3132
0.4846
0.4378
0.3973
0.3547
0.3060
1.0056
1.0099
1.0102
1.0136
1.0183
1.0152
1.0072
1.0100
1.0047
1.0097
1.0086
1.0018
1.0199
1.0259
1.0227
1.0240
1.0249
1.0243
1.0253
1.0259
1.0236
1.0250
1.0263
1.0244
1.0343
1.0383
1.0354
1.0390
1.0408
1.0419
1.0374
1.0393
1.0398
1.0365
1.0367
1.0343
344
342
340
338
336
0.0
0.2
0.4
x1 , y1
0.6
0.8
1.0
Fig. 1. Comparisons of T–x1 –y1 diagram for methanol + 2-propanol between experiment and literature at 101.3 kPa. , Ref. [8]; 夽, Ref. [9]; 䊉, this work.
Note: u(T) = ±0.01 K, u(x) = ±0.001, u(y) = ±0.001.
32
J. Wang, Z. Bao / Fluid Phase Equilibria 341 (2013) 30–34
Table 4
The physical properties of pure component.
Parameters
2-Propanol
Tc a /K
Pc a /MPa
Vc a /cm3 mol−1
Zc a
RD b /Å
c /D
qd
rd
The Antoine coefficientsa
A
B
C
T/K
508.3
4.764
222
0.25
2.726
1.679
2.51
2.78
6.40823
1107.303
−103.944
358–461
1-Butanol
563.0
4.414
274
0.258
3.225
1.679
3.052
3.4543
6.54172
1336.026
−96.348
323–413
1-Pentanol
588.1
3.897
326
0.26
3.679
1.799
3.592
4.1287
6.3975
1337.613
−106.567
326–411
Note:
a
Ref. [11].
b
Ref. [12].
c
Ref. [6].
d
Ref. [13].
where xi is the liquid-phase mole fraction of component i, yi is the
vapor-phase mole fraction of component i, p is the total pressure, i
is the activity coefficient of component i, ϕiv and ϕis are the fugacity
coefficient and the fugacity coefficient at saturation of component
i. The saturated vapor pressure psat
was calculated by the Antoine
i
equation:
lg ps (kPa) = A −
B
T (K) + C
(2)
p
(ViL /RT )dp is called Poynting coefficient. It can be con-
where exp
ps
i
sidered to be 1 at the moderate or low pressure conditions. So Eq
(1) can be written:
pyi ϕiv = xi i psat
ϕis
i
(3)
where ϕiv is:
p
ln ϕiv =
RT
⎧
⎨
⎫
⎬
1 Bii +
[yi yk (2ıji − ıjk )]
2
⎩
⎭
j
(4)
k
ıji and ıjk can be given by:
ıji = ıij = 2Bji − Bjj − Bii
(5)
ıjk = ıkj = 2Bjk − Bjj − Bkk
(6)
where Bii , Bjj and Bkk are the second term of the virial state equation;
Bji and Bjk are the cross second term of the virial state equation,
which are calculated by the Hayden and O’Connell method [10]. All
the physical properties required in this calculation are shown in
Table 4. The relationship between liquid-phase mole fractions and
activity coefficients is also displayed in Fig. 2.
We carried out Herington method which based on GibbsDuhem equation to check the thermodynamic consistency of
binary system. The method includes two parameters (D and J),
an area function and a temperature function, respectively. If
the value of (D − J) is less than 10, the isobaric VLE data pass
the thermodynamic consistency test. In this research, the results
(D − J) for 2-propanol + 1-butanol, 2-propanol + 1-pentanol and 1butanol + 1-pentanol system are 3.37, 0.72 and 2.25, respectively.
Obviously, all the binary isobaric data passed the thermodynamic
consistency test.
Fig. 2. Relationship between activity coefficients ( 1 ) and liquid-phase mole
fractions (x1 ) for (a) 2-prapanol (1) + 1-butanol (2) system, (b) 2-prapanol (1) + 1pentanol (2) system, and (c) 1-butanol (1) + 1-pentanol (2) system. 䊉, experimental
1 –x1 , —, correlated 1 –x1 ; , experimental 2 –x1 , - - -, correlated 2 –x1 .
3.2. Correlation for binary VLE data
In this research, the VLE data was correlated with the Wilson, NRTL, and UNIQUAC equations, respectively. The interaction
parameters of binary system were obtained by iterative solution,
and they were based on the maximum likelihood of objective function:
F=
N
n
exp 2
)n
[(ical − i
exp 2
+ (jcal − j
) ]
n
(7)
J. Wang, Z. Bao / Fluid Phase Equilibria 341 (2013) 30–34
Table 5
Regression parameters in equations for activity coefficients.
2-Propanol(1) + 1-butanol(2)
Wilson
−35.22
NRTL (˛ = 0.3)
4151.27
UNIQUAC
2512.93
2-Propanol(1) + 1-pentanol(2)
26.90
Wilson
−1966.54
NRTL (˛ = 0.3)
UNIQUAC
−568.78
1-Butanol(1) + 1-pentanol(2)
Wilson
−133.80
NRTL (˛ = 0.3)
3697.42
2305.76
UNIQUAC
410
405
A21 /(J mol−1 )
y1
T/K
56.87
−3027.73
−1793.08
0.0031
0.0029
0.0032
0.20
0.21
0.20
−25.49
1905.90
542.39
0.0037
0.0040
0.0049
0.26
0.40
0.49
648.30
−2967.98
−1754.10
0.0054
0.0047
0.0048
0.25
0.21
0.20
400
395
390
385
T/K
A12 /(J mol−1 )
Equation
380
375
370
365
360
355
0.0
Note: Wilson, A12 = (12 –11 ); NRTL, A12 = (g12 –g22 ); UNIQUAC, A12 = (u12 –u22 ).
exp
where ical , i
are the activity coefficients calculated by correlation and the activity coefficients calculated by Eq. (3). N refers to
the number of experiment data.
The average deviations (y and T) were expressed as:
N
exp
|ycal − yi
i=1 i
y =
N
T =
33
|
The regression parameters and average deviations (y and T)
are listed in Table 5. In Table 5, the deviation whether in vaporphase mole fraction or in temperature is very close among three
models, so we only showed the comparisons between experiment
data and the Wilson model regression results in Figs. 3–5.
0.6
0.8
1.0
N
(xic + xid ) (ln id − ln ic )
(11)
i=1
(9)
N
x1 , y1
The D and Dmax can be calculated by (11) and (12).
D=
|T − Texp |
i=1 cal
0.4
Fig. 4. T–x1 –y1 diagram for 2-prapanol (1) + 1-pentanol (2) at 101.3 kPa. 䊉, experimental data; —, Wilson regression p(x1 = 0) = 101.39 kPa, p(x1 = 1) = 101.20 kPa.
(8)
N
0.2
Dmax =
N
(xic + xid )
1
i=1
N
+2
xic
+
1
1
1
+
+
yic
xid
yid
x
|ln id − ln ic |x
i=1
3.3. Ternary system
The experimental VLE data of 2-propanol + 1-butanol + 1pentanol have been given in Table 3. The predictions of ternary
system with binary interaction parameters of Wilson, NRTL and
UNIQUAC equations were made. The correlation average deviations
in 2-propanol vapor-phase mole fraction were 0.0057, 0.0043, and
0.0049, and in temperature were 0.52, 0.50, and 0.49, respectively
for Wilson, NRTL and UNIQUAC models. The quality of results for
ternary system was tested by the McDermott-Ellis method [14],
which compares maximum deviation Dmax and local deference D
of the adjacent point c and d. The data passed the thermodynamic
consistent test if it satisfies:
|D| < Dmax
N
+
p +
(xic + xid )Bi
p
N
(xic − xid )
i=1
i=1
1
(Tc − Ci )2
+
1
(Td + Ci )2
x
(12)
where xic , xid , yic and yid refer to liquid-phase mole fraction and
vapor-phase mole fraction of adjacent point c and d respectively; Tc ,
Td , ic and id are temperature and activity coefficient of adjacent
points c and d; B and C are the Antoine constants; x, p and T are
the experiment errors of liquid-phase mole fraction, pressure and
temperature, respectively. In this research, x = 0.001, p = 0.065,
T = 0.1.
(10)
412
410
390
408
384
406
404
T/K
T/K
378
372
402
400
398
366
396
394
360
354
0.0
392
0.2
0.4
x ,y
1 1
0.6
0.8
1.0
Fig. 3. T–x1 –y1 diagram for 2-prapanol (1) + 1-butanol (2) at 101.3 kPa. 䊉, experimental data; —, Wilson regression p(x1 = 0) = 101.39 kPa, p(x1 = 1) = 101.23 kPa.
390
0.0
0.2
0.4
x ,y
0.6
0.8
1.0
1 1
Fig. 5. T–x1 –y1 diagram for 1-butanol (1) + 1-pentanol (2) at 101.3 kPa. 䊉, experimental data; —, Wilson regression p(x1 = 0) = 101.23 kPa, p(x1 = 1) = 101.20 kPa.
34
J. Wang, Z. Bao / Fluid Phase Equilibria 341 (2013) 30–34
4. Conclusions
The VLE data for 2-propanol + 1-butanol, 2-propanol + 1pentanol, 1-butanol + 1-pentanol and 2-propanol + 1-butanol + 1pentanol were obtained with an improved Rose still at 101.3 kPa.
We got the binary interaction parameters by regressing model
equations, and also made a prediction for every system, with a good
agreement between experiment data and correlation data. What is
more important is that the data both for binary and for ternary systems have passed the thermodynamic consistent test. At last, the
VLE data in our experiment conditions have few reports, so this
paper filled a blank in literature.
List of symbols
A12 , A21 interaction parameters
A, B, C
Antoine coefficients
Bii , Bjj , Bkk second virial coefficients
Bij , Bji , Bjk , Bkj cross second virial coefficients
objective function
F
N
number of components
nD
refractive index
pressure
P
q, r
structure parameters of UNIQUAC model
R
universal gas constant
RD
mean radius of gyration
T
absolute temperature
boiling point
Tb
V
liquid mole volume
x
liquid phase mole fraction
y
vapor phase mole fraction
compressibility factor
Zc
Greek letters
˛
adjustable parameter of NRTL model
ϕ
ω
activity coefficient
dipole moment
fugacity coefficient
eccentric factor
Superscripts and subscripts
calculated value
cal
exp
experimental value
sat, s
saturation property
v
vapor phase property
component i
i
j
component j
References
[1] X.G. Zhang, China Chemical Engineering News, 5th ed., 2012.
[2] K. Mara, V.R. Bhethanabotla, S.W. Campbell, Fluid Phase Equilib. 127 (1997)
147–153.
[3] N.A. Lebedinskaya, N.A. Filippov, V.I. Zayats, et al., Neftepererab. Neftekhim.
(Moscow) 2 (1974) 39.
[4] C.M. Wang, H.R. Li, L.H. Zhu, et al., Fluid Phase Equilib. 189 (2001)
119–127.
[5] E.F.G. Herington, J. Inst. Petrol. 37 (1951) 459–469.
[6] N.L. Cheng, Solvent Manual, Chemical Industry Press, Beijing, 2007.
[7] C.D. Zhang, H. Wan, L.J. Xue, et al., Fluid Phase Equilib. 305 (2011)
68–75.
[8] G.X. Zhang, L.W. Brandon, J.H. Wei, J. Chem. Eng. Data 52 (2007)
878–883.
[9] N. Gultekin, J. Chem. Eng. Data 35 (1990) 132–136.
[10] J.G. Hayden, J.P. O’Connell, Ind. Eng. Chem. Process Des. Dev. 14 (1975)
209–216.
[11] P.S. Ma, Chemical Engineering Thermodynamics, Chemical Industry Press, Beijing, 2005.
[12] A. Fredenslund, J. Gmehling, P. Rasmussen, Vapor–liquid Equilibria Using
UNIFAC—A Group Contribution Method, Elsevier Scientific Publishing Company, New York, 1977.
[13] J. Gmehling, U. Onken, Vapor–liquid Equilibrium Data Collection Chemistry
Data Series, Dechema, Frankfurt, 1977.
[14] C. McDermott, S.R.M. Ellis, Chem. Eng. Sci. 20 (1965) 293–296.