~
vv,---g,v,~! y
UII/! ELSEVIER
Fluid Phase Equilibria 109 (1995) 53-65
Isothermal vapour-liquid equilibria and excess volumes in the methanol-aliphatic ether systems Jana Ffirkovfi, Jan Linek, Ivan Wichterle Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6, Czech Republic Received 1 December 1994; accepted 8 February 1995
Abstract Vapour-liquid equilibria were measured isothermally in the binary systems containing methanol with butyl methyl ether, tert-butyl methyl ether, ethyl propyl ether, diisopropyl ether and butyl ethyl ether. The data were correlated using the Redlich-Kister, Wilson, and NRTL equations within the accuracy of experimental errors. The excess free volumes of liquid mixtures were determined and correlated at 25 °C.
Keywords: Experiments; Data; VLE low pressure; Excess volume; Methanol; Aliphatic ether
1. Introduction In this paper the results are presented of a continuing project dealing with phase equilibria in mixtures belonging to distinct families of organic compounds. Vapour-liquid equilibria in the mixtures containing methanol and aliphatic ether namely butyl methyl ether, tert-butyl methyl ether, ethyl propyl ether, diisopropyl ether and butyl ethyl ether were investigated each at two constant temperatures. In addition, the excess volumes were determined at 25 °C for the five systems as auxiliary thermodynamic information.
2. Experimental 2.1. Materials used
Methanol:technical product was selected as a raw material since other sources (of even much better quality) were curiously resistant to undergo the purification procedures in order to prepare the most pure product. The raw material was twice distilled, dried with sodium and rectified on a 30 plate 0378-3812/95/$09.50 © 1995 Elsevier Science B.V. All fights reserved
SSDI 0378-3812(95)02710-6
54
J. F6rkov6 et al. /Fluid Phase Equilibria 109 (1995) 53-65
Table 1 Physico-chemical properties of pure compounds Compound d(298.15K) Ref. Butyl methyl ether
0.73921
this work
Tert-butyl methyl ether
0.73542 0.7352
this work Evans and Edlund, 1 9 3 6
Ethyl propyl ether Diisopropyl ether
0.73015 0.71860 0.7182
this work this work Riddick and Bunger, 1970
Butyl ethyl ether
0.74379 0.7448
this work Riddick and Bunger, 1970
Methanol
0.78665 0.7865-75
this work Timmermans,1950
nD(293.15 K)
Ref.
1.37365 1.37364 1.3736 1.36887 1.36892 1.3689
this work Vogel, 1948 Cidlinsky and Pol~k, 1969 this work Aim and Ciprian, 1980 Evans and Edlund, 1936
1.36795 1.3681 1.3682 1.38149 1.38175 1.3817 1.32848 1.32846
this work Riddick and Bunger, 1970 Cidlinsky and Pol~k, 1969 this work Vogel, 1948 Cidlinsky and Pol~k, 1969 this work Aim and Ciprian, 1980
column packed with glass helices. Then, it was dried and stored over 4A molecular sieves. No impurities were detected by gas chromatography. Butyl methyl ether was synthesized from methyl iodide and sodium butanolate. Peroxides were removed with alumina, water was removed with metallic sodium. After rectification on 30 plate packed column the product was dried and stored over 4A molecular sieves. Purity determined by gas chromatography was 99.8%. Tert-butyl methyl ether, puriss, p.a. (better than 99.5%, Fluka, Switzerland) was used without further purification. It was dried and stored over 4A molecular sieves. Purity determined by gas chromatography was better than 99,9%. Ethyl propyl ether was synthesized from ethyl iodide and sodium propanolate. After rectification (with hydroquinone) on 30 plate packed column it was stored over 4A molecular sieves. Purity determined by gas chromatography was 99.2%. Diisopropyl ether, puriss, p.a. (better than 99%, Fluka, Switzerland) was dried and stored over 4A molecular sieves. Purity determined by gas chromatography was better than 99.5%. Butyl ethyl ether was synthesized from sodium butanolate and ethyl iodide. After rectification from sodium on 30 plate packed column it was stored over metallic sodium. Purity determined by gas chromatography was better than 99.4%. The quality of the above compounds is characterized by density and refractive index. The two physico-chemical properties are summarized in Table 1 where the literature data (if available) can be found for comparison. 2.2. E x c e s s v o l u m e d e t e r m i n a t i o n
The mixtures were prepared by successive weighing of pure components so that composition was obtained with accuracy of 0.0001 mole%. Their densities were determined at 25.00 °C using a DMA 60 + 602 vibrating-tube densimeter (A. Paar, Austria). The temperature of the densimeter measuring
J. F6rkov:~ et al. / Fluid Phase Equilibria 109 (1995) 53-65
55
Table 2 Experimental excess volumes (cm 3 m o l - 1 ) of the methanol (m)-ether systems at 298.15 K Xm
VE
Butyl methylether 0.0414 -0.0627 0.0854 -0.1176 0.1393 -0.1743 0.1734 -0.2031 0.2510 -0.2495 0.3114 -0.2718 0.4092 -0.2898 0.5458 -0.2789 0.6347 -0.2518 0.7049 - 0.2231 0.7846 -0.1787 0.8293 -0.1485 0.8818 -0.1084 0.9304 -0.0681 Diisopropylether 0.0532 -0.2451 0.1088 -0.4533 0.1668 -0.6195 0.1697 -0.6261 0.2742 -0.8400 0.3521 -0.9262 0.4653 -0.9844 0.6101 -0.9326 0.6776 - 0.8656 0.7745 -0.7057 0.8116 -0.6248 0.8707 -0.4799 0.9031 -0.3756 0.9535 -0.1968
AV E
xm
VE
AV E
xm
-2.41 1.06 1.09 0.76 -0.44 - 1.21 0.59 - 1.64 - 0.10 2.20 2.76 -4.04 0.98 - 1.68
Ethylpropylether 0.0459 -0.1419 0.0873 -0.2332 0.1373 -0.3225 0.1795 -0.3807 0.2489 -0.4563 0.3202 -0.5041 0.4183 -0.5345 0.5032 -0.5351 0.6205 -0.4940 0.7097 -0.4343 0.7757 -0.3662 0.8261 -0.3110 0.8805 -0.2299 0.9295 -0.1449
te~-Butylmethylether 0.0377 -0.1122 0.0910 -0.2419 0.1356 -0.3358 0.1800 -0.4150 0.2464 -0.5097 0.3441 -0.6022 0.3977 -0.6300 0.4959 -0.6523 0.6165 -0.6176 0.6838 -0.5683 0.7738 -0.4697 0.8357 -0.3825 0.8863 -0.2826 0.9411 -0.1615 Butylethylether 0.0456 -0.1018 0.0998 -0.1961 0.1503 -0.2635 0.2028 -0.3136 0.2728 -0.3593 0.3533 -0.3888 0.4451 -0.3937 0.5524 -0.3746 0.6492 -0.3319 0.7211 -0.2869 0.8025 -0.2215 0.8454 -0.1822 0.8971 -0.1280 0.9470 -0.0699
-0.61 0.16 - 1.01 - 1.25 0.60 1.79 0.56 -0.87 -0.10 - 1.18 -0.48 0.51 1.35 0.45 - 1.88 -3.21 1.59 2.45 - 1.84 3.18 - 1.86 -0.71 - 2.24 2.66 4.25 - 4.29 0.13 -0.92
VE
AV E
- 12.3 -6.75 - 1.34 3.76 4.27 4.59 1.85 - 3.24 -4.17 -3.91 2.82 - 6.36 3.28 4.39
-3.39 -3.42 - 2.55 1.03 3.55 2.48 1.95 - 2.81 - 3.16 -2.00 1.07 1.41 2.48 1.87
A V E = ( VcaElc_ V E) X 103 (cm 3 m o l - 1). cell was controlled to _ 0.01 K. The densimeter was tested and calibrated by measuring the density of w a t e r a n d c y c l o h e x a n e o f s p e c i a l p u r i t y . T h e a c c u r a c y o f t h e d e n s i t y d e t e r m i n a t i o n is e s t i m a t e d t o b e better than _ 0.00002 g cm -3.
Table 3 Correlation of excess volumes of the methanol-ether systems at 298.15 K AI Butyl methyl ether tea-Butyl methyl ether Ethyl propyl ether Diisopropyl ether Butyl ethyl ether
-
1.14475 2.60224 2.12967 3.92848 1.54746
A2
A3
-
-
0.27262 0.05931 0.35524 0.23868 0.45610
Mean absolute deviation AV E -- (Vcalc E - V E) )< 103 (cm 3 m o l - 1).
AV E
0.20007 0.42972 0.61584 0.85828 0.36158
0.78 1.50 4.01 2.23 2.37
56
J. F6rkov~ et al. / Fluid Phase Equilibria 109 (1995) 53-65
2.3. Vapour-liquid equilibrium determination The vapour-liquid equilibrium was measured using a recirculation stills with total volume of liquid mixture of about 150 ml. The temperature was measured with either the Hewlett-Packard quartz
120 P/kPa 100
I
,
,
,
,
I
I
I
b
a, p/ki :
80 60'
60' 3t0K
40
,0
20 0 0 1201
I
I
I
0I 0
0.2 0.4 0.6 0.8 Molefractionof methanol I
I
I
I
I
801"
I
I
I
I
I
I
I
d
~
,°I
40,
40
2(1
I
0
120 P/kPa 100
I
0.2 0.4 0.6 0.8 Molefractionof methanol
80
60 -
0
315K
20120
I
_
I
I
I
2oF oI o
0.2 0.4 0.6 0.8 Molefraction of methanol
I I I I 0.2 0.4 0.6 0.8 Molefractionofmethanol
0000200
120 P/kPa
I
I
I
I
e
315K 0 0
I I i I 0.2 0.4 0.6 0.8 Mole fraction of methanol
Fig. 1. Vapour-liquid equilibria in the methanol-ether systems. (a) methanol-butyl methyl ether; (b) methanol-tert-butyl methyl ether; (c) methanol-ethyl propyl ether; (d) methanol-diisopropyl ether; (e) methanol-butyl ethyl ether. Lines are calculated from the NRTL equation.
J. F6rkov~ et al./ Fluid Phase Equilibria 109 (1995) 53-65
57
thermometer or precise mercury thermometers (10 K range), both calibrated against a platinum resistance thermometer traceable to NBS (Washington DC, USA). The absolute accuracy of temperature measurement is +0.01 K of temperature on the IPTS-68. The pressure in the system was controlled by a mercury manostat and adjusted to the boiling point of the mixture on the isotherm under study and determined indirectly from the boiling point of water in an ebulliometer connected in parallel to the equilibrium still. The accuracy of pressure measurement is believed to be __+0.01 kPa. The details of the apparatus, procedure and calibration can be found elsewhere (Polednov~ and Table 4 Vapor-liquid equilibria in the methanol-butyl methyl ether system Xm
Ym
P /kPa
Ax
Ay
AP /kPa
AT / K
0.0000
0.0000
30.67
.
0.0288
0.1161
33.50
0.0036
0.0100
- 0.03
0.0685
0.2224
37.16
- 0.0006
0.0004
- 0.00
0.00
0.0916
0.2626
38.52
- 0.0003
0.0002
0.00
- 0.00
0.1315
0.3115
40.30
0.0009
- 0.0023
0.01
- 0.00
0.1934
0.3629
42.07
0.0041
- 0.0040
- 0.01
0.00
0.3547
0.4518
44.33
- 0.0019
0.0009
0.03
- 0.01
0.4785
0.4897
44.68
0.0005
- 0.0016
0.00
0.00
0.5891
0.5260
44.52
0.0002
- 0.0007
- 0.00
0.00
0.6725
0.5580
44.02
- 0.0005
0.0005
- 0.01
0.00
0.7664
0.6048
42.83
- 0.0015
0.0010
- 0.01
0.00
0.8195
0.6417
41.68
- 0.0017
0.0012
- 0.00
0.00
0.8649
0.6846
40.25
- 0.0012
0.0017
0.00
- 0.00
0.9028
0.7324
38.60
- 0.0003
0.0014
0.00
- 0.00
0.9416
0.8031
36.23
0.0002
0.0012
0.00
- 0.00
0.9643
0.8655
34.33
- 0.0005
0.0025
0.01
- 0.00
0.9909
0.9558
31.70
0.0005
0.0004
0.00
- 0.00
0.9974
0.9853
30.92
0.0004
0.0002
0.00
0.00
1.0000
1.0000
30.54
.
.
0.0000
0.0000
65.17
.
.
0.0326
0.1296
72.74
0.0018
0.0023
- 0.00
0.00
0.0717
0.2360
80.22
- 0.0007
0.0013
- 0.00
0.00
0.0984
0.2777
83.48
0.0020
- 0.0001
- 0.00
0.00
0.1427
0.3310
87.81
0.0051
- 0.0025
- 0.00
0.00
0.2006
0.3871
92.34
0.0006
- 0.0045
0.01
- 0.00
0.3691
0.4833
98.21
- 0.0007
- 0.0009
0.01
- 0.01
0.5807
0.5611
99.90
0.0013
- 0.0017
0.04
- 0.02
0.6615
0.5935
99.14
- 0.0007
- 0.0018
- 0.02
0.01
0.7549
0.6392
97.20
- 0.0045
- 0.0035
- 0.03
0.02
0.8079
0.6735
95.40
- 0.0033
- 0.0028
- 0.02
0.01
0.8537
0.7122
93.54
0.0043
0.0042
0.02
- 0.01
0.8924
0.7554
90.57
0.0021
0.0036
0.01
- 0.01
0.9339
0.8187
86.15
0.0012
0.0030
0.01
- 0.01
0.9601
0.8725
82.41
0.0012
0.00
- 0.00
1.0000
1.0000
74.30
.
T = 310.00 K .
.
.
.
.
.
.
0.01
T = 330.00 K
A = experimental-calculated
(NRTL).
0.0017 .
.
.
J. F6rkov6 et al. / Fluid Phase Equilibria 109 (1995) 53-65
58
Wichterle, 1984). Special care had to be paid to handling of all mixtures because of their hygroscopicity. Samples withdrawn for analysis (even though in small glass grounded flasks) were kept in a desiccator filled with silica gel. In all cases the density measurements were exploited as analytical tool for determination of composition.
Table 5 Vapor-liquid equilibria in the methanol-tert-butyl methyl ether system Xm T = 315.00 K 0.0000 0.0402 0.0993 0.1594 0.2362 0.3728 0.4192 0.4955 0.6509 0.6993 0.7539 0.8261 0.8712 0.9013 0.9398 0.9931 1.0000 T = 325.00 K 0.0000 0.0413 0.1158 0.1932 0.2397 0.3040 0.3786 0.4471 0.5087 0.5772 0.6062 0.7111 0.7918 0.8506 0.8911 0.9158 0.9619 0.9957 1.0000
Ym
P /kPa
Ax
0.0000 0.0737 0.1511 0.1997 0.2550 0.3229 0.3424 0.3751 0.4489 0.4804 0.5167 0.5865 0.6436 0.6950 0.7819 0.9657 1.0000
63.97 66.42 68.80 70.17 70.98 70.65 70.23 69.19 65.79 64.04 61.80 57.64 54.46 51.82 47.51 39.94 38.71
. 0.0013 0.0002 0.0015 -0.0009 -0.0004 0.0000 0.0000 0.0004 -0.0023 -0.0022 -0.0052 -0.0038 - 0.0033 - 0.0033 - 0.0003 .
0.0000 0.0790 0.1772 0.2420 0.2723 0.3097 0.3466 0.3779 0.4064 0.4377 0.4526 0.5112 0.5759 0.6352 0.6967 0.7389 0.8528 0.9714 1.0000
90.91 95.02 99.67 102.05 102.74 103.15 102.96 102.27 101.14 99.50 98.71 94.44 89.05 84.07 79.47 76.01 68.12 61.49 60.10
. 0.0005 -0.0006 -0.0002 0.0001 -0.0004 -0.0004 -0.0004 -0.0010 -0.0011 -0.0009 -0.0014 -0.0055 -0.0038 -0.0040 -0.0034 -0.0024 0.0013 .
A = experimental-calculated (NRTL).
Ay .
. .
.
. 0.0013 0.0019 -0.0018 0.0013 0.0019 0.0013 0.0011 0.0011 0.0029 0.0016 0.0023 0.0032 0.0050 0.0047 0.0014 . . 0.0003 0.0011 0.0002 -0.0001 0.0008 0.0013 0.0018 0.0028 0.0028 0.0036 0.0033 0.0034 0.0016 0.0037 0.0008 - 0.0019 - 0.0009 .
AP /kPa
AT / K
-0.07 -0.09 -0.01 0.06 0.06 0.06 0.04 0.04 -0.01 -0.02 -0.03 0.01 0.04 0.04 0.02
0.02 0.02 0.00 -0.01 -0.02 -0.01 -0.01 -0.01 0.00 0.01 0.01 -0.00 - 0.02 - 0.02 - 0.01
-0.03 -0.03 0.01 0.01 0.03 0.07 0.09 0.03 0.02 0.07 0.03 -0.06 -0.03 0.03 -0.02 -0.05 -0.01
0.00 0.00 -0.00 -0.00 -0.01 -0.01 -0.01 -0.01 -0.00 -0.01 -0.01 0.01 0.01 -0.01 0.00 0.01 0.00
.
. .
.
J. F[trkov~et al. / Fluid Phase Equilibria 109 (1995) 53-65
59
3. Results and correlation The experimental data on excess volume V E are published in tabular sheet form by Linek (1995) and are summarized in Table 2. The densities of pure components needed for calculation are those experimentally determined and summarized in Table 1. The Redlich-Kister equation of the 4th order
V E = XmXe[a l + a2( Xm
-- Xe) +
a3(
Xm -
X e ) 2]
was used for correlation where x m and x e are the mole fractions of pure methanol (m) and ether (e), respectively. The least square and the maximum likelihood method were applied for evaluation of the three adjustable parameters A1, A2, and A 3. Nevertheless, both the procedures provide practically identical result. The correlations obtained along with average deviations from smoothed data are presented in Table 3. Vapour-liquid equilibria were measured at constant temperature over the whole concentration range and published briefly as sheet communication by Ffirkovfi et al. (1995). The experimental data
Table 6 Vapor-liquid equilibria in the methanol-ethyl propyl ether system Xm
Ym
P /kPa
Ax
Ay
AP /kPa
AT / K
T = 310.00 K 0.0000
0.0000
39.37
.
0.0542
0.0678
42.16
0.0257
.
- 0.0209
.
. 0.04
- 0.02
0.1165
0.1541
45.43
0.0407
- 0.0338
0.04
- 0.01
0.1677
0.2154
47.53
0.0445
- 0.0373
- 0.01
0.00
0.2261
0.2673
49.17
0.0406
- 0.0417
- 0.08
0.03
0.2840
0.3159
50.41
0.0195
- 0.0391
- 0.02
0.01
0.4376
0.3658
51.02
0.0129
- 0.0452
0.02
- 0.00
0.6014
0.4215
50.46
0.0160
- 0.0353
0.09
- 0.03
0.7510
0.4930
48.41
0.0245
- 0.0218
0.08
- 0.03
0.8560
0.5859
44.65
0.0201
- 0.0125
0.02
- 0.01
0.9341
0.7115
39.55
0.0174
- 0.0071
0.00
- 0.00
0.9707
0.8214
35.64
0.0122
- 0.0047
- 0.00
0.00
1.0000
1.0000
30.54
.
.
0.0000
0.0000
82.25
.
.
0.0495
0.0908
89.89
0.0154
- 0.0194
0.01
- 0.02
0.1133
0.1722
96.71
0.0364
- 0.0298
0.07
- 0.01
0.1651
0.2409
101.82
0.0407
- 0.0293
- 0.04
0.01
0.2244
0.2973
106.25
0.0365
- 0.0342
- 0.12
0.02
0.3062
0.3515
109.84
0.0248
- 0.0388
- 0.15
0.02
0.4257
0.4151
112.15
0.0105
- 0.0312
0.12
- 0.01
0.5868
0.4711
111.74
0.0133
- 0.0297
0.18
- 0.02
0.7296
0.5352
108.92
0.0210
- 0.0214
0.22
- 0.03
0.8450
0.6208
102.31
0.0172
- 0.0155
0.03
- 0.00
0.9240
0.7332
93.03
0.0117
- 0.0098
- 0.02
0.00
0.9645
0.8322
85.38
0.0088
- 0.0060
- 0.02
0.00
1.0000
1.0000
74.30
.
.
.
.
.
T = 330.00 K
A = experimental-
calculated (NRTL).
.
.
.
J. Fftrkovd et al. / Fluid Phase Equilibria 109 (1995) 53-65
60
Table 7 Vapor-liquid equilibria in the methanol-diisopropyl ether system
Xm T = 320.00 K 0.0000 0.0318 0.0514 0.1212 0.1628 0.2692 0.3503 0.4789 0.5847 0.6842 0.7789 0.8533 0.9094 0.9535 0.9764 0.9899 1.0000 T = 330.00K 0.0000 0.0247 0.0619 0.0975 0.1858 0.3681 0.5187 0.5307 0.6314 0.7310 0.7680 0.8481 0.8805 0.9139 0.9494 0.9729 0.9835 0.9939 1.0000
Ym
P /kPa
Ax
Ay
0.0000 0.1012 0.1530 0.2737 0.3206 0.3979 0.4390 0.4914 0.5273 0.5753 0.6348 0.6996 0.7697 0.8489 0.9153 0.9588 1.0000
48.40 52.02 54.24 60.17 62.50 66.09 67.50 68.43 68.28 67.37 65.34 62.40 58.80 54.87 51.82 49.98 48.44
. 0.0040 0.0039 0.0028 0.0026 0.0035 0.0030 0.0019 0.0029 0.0007 -0.0029 -0.0037 - 0.0027 0.0003 -0.0011 -0.0003 .
.
0.0000 0.0824 0.1761 0.2484 0.3480 0.4631 0.5248 0.5295 0.5691 0.6158 0.6428 0.7122 0.7472 0.7920 0.8531 0.9085 0.9409 0.9742 1.0000
68.90 73.21 79.17 84.41 92.51 99.92 101.54 101.62 101.14 99.50 98.36 94.10 91.51 88.11 83.60 79.79 77.80 75.70 74.24
. 0.0038 0.0069 0.0050 0.0076 0.0046 0.0021 0.0019 0.0012 0.0005 -0.0017 -0.0059 -0.0058 -0.0049 -0.0021 -0.0007 - 0.0003 0.0003 .
.
.
.
. 0.0068 0.0067 0.0006 -0.0013 -0.0059 -0.0070 -0.0057 -0.0071 0.0001 0.0057 0.0069 0.0041 0.0010 -0.0009 -0.0014 .
.
. 0.0053 0.0046 0.0021 -0.0079 -0.0104 -0.0063 -0.0058 -0.0023 0.0007 0.0056 0.0089 0.0072 0.0045 0.0012 -0.0006 0.0000 - 0.0008 .
.
AP /kPa
AT / K
-0.03 -0.04 - 0.01 - 0 .0 1 0.00 0.00 0.02 0.02 0.02 0.01 0.02 0.01 0.00 - 0 .0 1 - 0 .0 1
0.04 0.04 0.01 0.01 0.00 -0.00 -0.02 -0.02 -0.02 - 0 .0 1 -0.02 -0.01 - 0 .0 1 0.01 0.01
-0.04 -0.05 -0.03 -0.00 -0.00 0.03 0.04 0.02 0.02 0.03 0.03 0.02 0.01 0.00 - 0 .0 1 - 0.00 - 0.00
0.03 0.03 0.03 0.00 0.00 - 0.01 -0.02 - 0.01 - 0 .0 1 -0.02 -0.02 -0.02 - 0 .0 1 -0.00 0.00 0.00 0.00
.
.
A = experimental --calculated (NRTL).
are s h o w n in Fig. 1 a n d are s u m m a r i z e d in T a b l e s 4 - 8 .
A z e o t r o p i c b e h a v i o u r w a s f o u n d in all
systems investigated. The azeotropic points determined by graphical interpolation of experimental data are p r e s e n t e d in T a b l e 9. In the data r e d u c t i o n a m a x i m u m l i k e l i h o o d p r o c e d u r e w a s u s e d as d e s c r i b e d b y Hfila et al. ( 1 9 8 2 ) . A s y m m e t r i c a l o b j e c t i v e f u n c t i o n w a s e v a l u a t e d u s i n g s t a n d a r d d e v i a t i o n s e s t i m a t e d as o"x =O'y =
J. F6rkov6 et al. / Fluid Phase Equilibria 109 (1995) 53-65
61
Table 8 V a p o r - l i q u i d equilibria in the m e t h a n o l - b u t y l ethyl ether s y s t e m
Xm
Ym
P /kPa
Ax
Ay
T = 315.00 K 0.0000 0.0470 0.1055 0.1413 0.2585 0.3374
0.0000 0.3033 0.4871 0.5380 0.6310 0.6597
16.44 22.90 29.42 32.00 37.07 38.99
. 0.0066 0.0019 0.0012 - 0.0006 0.0001
0.4811 0.6248
0.6984 0.7352
41.00 42.24
0.0020 0.0006
- 0.0047 - 0.0021
0.7647 0.8583 0.8934 0.9482 0.9738
0.7742 0.8175 0.8425 0.8990 0.9394
42.80 42.59 42.25 41.13 40.19
0.0007 0.0007 0.0007 0.0011 0.0012
-
0.9919 1.0000 T = 335.00 K 0.0000 0.0335 0.0761 0.0942 0.1239 0.2049 0.3766 0.5227 0.6672 0.7809 0.8255 0.9063 0.9711
0.9781 1.0000
39.25 38.69
0.0007 .
0.0000 0.2455 0.4010 0.4556 0.5140 0.5966 0.6781 0.7198 0.7592 0.7956 0.8143 0.8658 0.9415
36.61 47.30 57.16 62.00 68.12 78.15 89.73 94.71 97.69 98.75 98.78 97.66 94.27
1.0000
1.0000
91.11
. 0.0017 0.0063 0.0020 - 0.0022 0.0006 0.0031 0.0025 0.0008 0.0007 0.0008 0.0007 0.0008 .
.
. - 0.0028 0.0007 - 0.0014 0.0010 - 0.0027
.
.
. 0.0000 0.0051 0.0034 0.0006 0.0018 0.0072 0.0080 0.0046 0.0021 0.0016 0.0001 0.0000 .
AT/K
0.01 - 0.01 0.00 0.00 0.02
- 0.01 0.01 - 0.00 - 0.00 - 0.01
- 0.03 - 0.01
0.01 0.00
.
0.0020 0.0009 0.0002 0.0002 0.0002 0.0000 .
.
AP /kPa
0.02 0.01 0.02 0.01 0.01
-
0.01
- 0.00
- 0.00 - 0.08 - 0.05 0.01 0.01 - 0.03 - 0.05 0.07 0.07 0.07 0.05 0.02
0.00 0.02 0.01 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.00
. .
-
-
.
A = experimental -- calculated (NRTL). Table 9 Azeotropic points of the methanol ( m ) - e t h e r s y s t e m s Ether
T/K
Butyl methyl ether
310
44.75
0.494
330 315 325 310 330 320 330 315 335
100.02 71.36 103.15 51.24 112.25 68.47 101.61 42.82 98.84
0.549 0.284 0.314 0.355 0.405 0.500 0.539 0.777 0.801
tert-Butyl methyl ether Ethyl propyl ether Diisopropyl ether Butyl ethyl ether
P/kPa
0.01 0.01 0.01 0.01 0.00
xm
62
J. F{~rkov(let al. / Fluid Phase Equilibria 109 (1995) 53-65
Table 10 Parameters of correlation equations and mean deviations for the methanol-butyl methyl ether system Ame
T/K
Aem
D(R-K) or a(NRTL) /ix
Redlich-Kister equation (3rd order) 310.00 1.5226 -0.0086 330.00 1.4350 0.0202 Redlich-Kister equation (4th order) 310.00 1.5157 -0.0120 0.1327 330.00 1.4271 0.0096 0.1367 Wilson equation 310.00 5775.01 -628.303 330.00 5796.40 -748.011 NRTL equation 310.00 1530.69 1 4 9 5 . 3 4 -1.0213 330.00 1485.34 1516.27 - 1.1503
/iy
AP/kPa
AT/K
0.0039 0.0064 0.03 0.0057 0.0075 0.02
0.01 0.02
0.0012 0.0018 0.01 0.0022 0.0025 0.01
0.00 0.01
0.0014 0.0026 0.01 0.0029 0.0034 0.01
0.00 0.01
0.0011 0.0018 0.01 0.0021 0.0024 0.01
0.00 0.01
0.001, O-p 0.1% of actual pressure (kPa), tr T = 0.01 K for phase compositions, pressure and temperature, respectively. The real gas phase behaviour was taken into the account; the whole correlation procedure is described elsewhere (Wolfovfi et al., 1990). The necessary second virial coefficients were calculated by the H a y d e n and O ' C o n n e l l (1975) method while the m o l a r v o l u m e s were calculated by using a generalized W a t s o n relation ( H o u g e n and Watson, 1947) for both the pure c o m p o n e n t s and mixtures. The experimental v a p o u r pressures were used for all calculations which is generally recognized and r e c o m m e n d e d procedure for isothermal data. The activity coefficients were fitted both to classical ( R e d l i c h - K i s t e r ) and to non-classical equations (Wilson or N R T L ) . The results of correlation are presented in Tables 1 0 - 1 4 . Here, the parameters Ame and Aem for the Wilson and N R T L equation are expressed in J mo1-1. It is obvious that m e a n deviations generally agree with the estimated standard deviations used in the correlation procedure so confirming its reliability. As an illustration, the deviations in compositions, pressure and =
Table 11 Parameters of correlation equations and mean deviations for the methanol-tert-butyl methyl ether system T/K
Ame
Aem
D(R-K) or a(NRTL) Ax
Redlich-Kister equation (3rd order) 315.00 1.2001 -0.0316 325.00 1.1912 -0.0063 Redlich-Kister equation (4th order) 0.1023 315.00 1.1922 - 0.0226 0.0832 325.00 1.1856 - 0.0017 Wilson equation 315.00 4831.10 - 1011.22 325.00 4827.81 - 927.24 NRTL equation 315.00 1247.19 1178.40 -1.2767 325.00 1272.16 1267.03 -1.1412
/iy
/iP/kPa / I T / K
0.0024 0.0042 0.08 0.0022 0.0035 0.09
0.02 0.01
0.0017 0.0022 0.04 0.0016 0.0018 0.03
0.01 0.01
0.0017 0.0030 0.04 0.0018 0.0024 0.04
0.01 0.01
0.0017 0.0022 0.04 0.0016 0.0018 0.04
0.01 0.01
J. FArkov[tet al./ FluidPhaseEquilibria 109 (1995)53-65
63
Table 12 Parameters of correlation equations and mean deviations for the methanol-ethyl propyl ether system
T/K
Ame
Redlich-Kister equation (3rd order) 310.00 1.5003 330.00 1.4371 Redlich-Kister equation (4th order) 310.00 1.4929 330.00 1.4331 Wilson equation 310.00 5666.74 330.00 5507.10 NRTL equation 310.00 1804.56 330.00 1566.77
D(R-K) or a(NRTL) Ax
ACre
Ay
AP/kPa A T / K
-0.0314 -0.0060
-
0.0236 0.0213
0.0289 0.0240
0.10 0.09
0.00 0.01
-0.0487 0.0066
0.0341 0.0887
0.0248 0.0212
0.0273 0.0244
0.03 0.09
0.01 0.01
-
0.0250 0.0259 0.0216 0.0239
0.11 0.10
0.04 0.01
0.0249 0.0272 0.04 0.0215 0.0241 0.10
0.01 0.01
-681.115 -448.359 1498.71 1581.56
-0.5140 -0.8856
Table 13 Parameters of correlation equations and mean deviations for the methanol-diisopropyl ether system
T/K
Ame
Redlich-Kister equation (3rd order) 320.00 1.3883 330.00 1.3950 Redlich-Kister equation (4th order) 320.00 1.3836 330.00 1.3916 Wilson equation 320.00 5453.49 330.00 5561.27 NRTL equation 320.00 1412.33 330.00 1431.56
D(R-K) or ot(NRTL) Ax
Aem
Ay
AP/kPa A T / K
0.0056 0.0054
0.0413 0.0664
-
0.0021 0.0024
0.02 0.02
0.02 0.02
0.0393 0.0582
0.0728 0.0621
0.0024 0.0041 0.01 0.0032 0.0045 0.02
0.02 0.01
-
0.0025 0.0040 0.01 0.0036 0.0042 0.02
0.01 0.01
0.0024 0.0033
0.01 0.01
-762.948 -677.676 1586.58 1719.81
-0.8196 -0.7429
0.0041 0.0044
0.01 0.02
Table 14 Parameters of correlation equations and mean deviations for the methanol-butyl ethyl ether system
T/K
Ame
Redlich-Kister equation (3rd order) 315.00 1.5963 335.00 1.5267 Redlich-Kister equation (4th order) 315.00 1.5932 335.00 1.5144 Wilson equation 315.00 5613.56 335.00 5571.71 NRTL equation 315.00 1488.71 335.00 1440.25
Aem
D (R-K) ot (NRTL) Ax
Ay
AP/kPa A T/ K
0.1036 0.1309
-
0.0045 0.0040
0.0047 0.0040
0.09 0.21
0.04 0.04
0.0674 0.1119
0.1700 0.1493
0.0015 0.0019
0.0014 0.0028
0.02 0.05
0.01 0.01
-
0.0017 0.0019
0.0018 0.0028
0.03 0.07
0.01 0.01
0.0014 0.0019
0.0015 0.0029
0.01 0.04
0.01 0.01
37.548 91.053 1675.31 1796.01
-1.0895 -1.0671
64
J. F6rkov6 et al. / Fluid Phase Equilibria 109 (1995) 53-65
temperature corresponding to the correlation using the NRTL equation are presented in Tables 4 - 8 along with the direct experimental data.
4. Discussion For the system methanol-diisopropyl ether only two isobaric (at around atmospheric pressure) data sets of not very high quality were found in the bibliography (Wichterle et al., 1994). Therefore, no comparison was possible. Similarly, from the eight available data sets for the methanol-tert-butyl methyl ether system, only two of them could be used for comparison. The isotherms at 40 and 50 °C were measured by Mullins et al. (1989) using a not very reliable still; the another isotherm (25 °C) was measured by Velasco et al. (1990). The latter was correlated using the procedure described above and obtained results are in accordance with the data given in Table 12. No data were found for the other systems. Generally, the distribution of deviations from smoothed data confirms that there are expectable errors. Moreover, the data obeying these equations must be thermodynamically consistent. The only exclusion concerns the methanol-ethyl propyl ether system, however, thorough inspection of the experiment has not reveal any reasons confirming systematic errors and consequently, that these data are correct as determined.
Acknowledgements The authors would like to acknowledge the partial support of the Grant Agency of the Czech Republic; the work has been carried out under grant No. 104/93/2288. The authors would like to acknowledge the assistance of Ing. O. Drfibek in synthesis and purification of chemicals involved.
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Polednovfi, J. and Wichterle I., 1984. Vapour-liquid equilibrium in the acetone-water system at 101.325 kPa. Fluid Phase Equilibria, 17: 115-121. Riddick, J.A. and Bunger, W.B., 1970. Organic Solvents. In: Techniques of Chemistry. Vol. II, Wiley-Interscience, New York. Timmermans, J., 1950, 1965. Physico-chemical Constants of Pure Organic Compounds, Elsevier, Amsterdam. Velasco, E., Cocero, M.J. and Mato, F., 1990. Salt effect on vapor-liquid equilibrium of methyl tert-butyl ether + methanol at 298.15 K.J. Chem. Eng. Data 35: 21-35. Vogel, A.I., 1948. Physical properties and chemical constitution. XII. Ethers and Acetals. J. Chem. Soc. 616: 624. Wichterle, I., Linek, J., Wagner, Z., Kehiaian, H.V., 1994. Vapor-liquid Equilibrium Bibliographic Database, Eldata, Paris, 724 pp. Wolfovfi, J., Linek, J. and Wichterle, I., 1990. Vapour-liquid equilibria in the heptane-3-pentanol and heptane-2-methyl2-butanol systems at constant temperature. Fluid Phase Equilibria, 54: 69-79.