Isothermal vapour-liquid equilibria and excess volumes in the methanol-aliphatic ether systems

Isothermal vapour-liquid equilibria and excess volumes in the methanol-aliphatic ether systems

~ vv,---g,v,~! y UII/! ELSEVIER Fluid Phase Equilibria 109 (1995) 53-65 Isothermal vapour-liquid equilibria and excess volumes in the methanol-ali...

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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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65

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.