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Fluid Phase Equilibria, 3 (1979) 35-46 35 0 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
GAS-LIQUID EQUILIBRIUM IN HYDROGEN + TETRALIN + DIPHENYLMETHANE AND HYDROGEN + TETRALIN + m-XYLENE
JOSEPH L. OLIPHANT, HO-MU LIN and KWANGCHU CHAO *
SchooE of Chemical Engineering, Purdue University, West Lafayette, IN 47907 (U.S.A.)
(Received July 24rd, 1978; accepted in revised form November 9th, 1978)
ABSTRACT
Oliphant J.L., Lin, H.M. and Chao, K.-C., 1979. Gas-liquid equilibrium in hydrogen + tetra- lin + diphenylmethane and hydrogen + tetralin + m-xylene. Fluid Phase Equilibria, 3: 35-46. Vapor--liquid equilibrium data in two ternary mixture systems, hydrogen + tetralin +
diphenylmethane and hydrogen + tetralin + m-xylene, were determined in a flow apparatus at pressures 20-250 atm ** for both systems, and temperatures 190-430°C for the first system and 190-310°C for the second. Mixed solvents approximately equi-molal in the organic compounds were studied. Henry constants of hydrogen in the mixed solvents were evaluated from the data. The results show that the solubility of hydrogen in these mixed hydrocarbon solvents can be completely predicted from solubilities in the pure component liquids.
INTRODUCTION
Gas-liquid equilibrium in mixtures of hydrogen and hydrocarbons is of interest to industrial processes such as coal liquefaction and hydrotreating. Simnick et al. (1977) reported a survey of the literature, concluding that there was a general deficiency of data particularly at conditions of greatest industrial interest at elevated temperatures and pressures. Subsequently, experimental studies of several binary mixtures of hydrogen and a hydrocar- bon in this laboratory have been reported (Simnick et al., 1977,1978; Yao et al., 1978). The present work extends our studies to ternary systems of hydro- gen and mixed solvents. No previous results of this kind have been reported. The new data on gas solubility in mixed solvents should be of value for devel- oping correlations and for testing theories that describe mixed solvents (O’Connell, 1971).
The mixed solvents, tetralin + diphenylmethane and tetralin + m-xylene, were chosen for this study because binary mixtures of hydrogen with each of the three pure solvents have been studied (Simnick et al., 1977,1978, and 1979).
* To whom correspondence should be addressed. ** 1 atm = 101.325 kPa.
Solutions of tetralin + diphenylmethane are made up of highly similar com- ponents, while tetralin + m-xylene of relatively different components. The se!ubility parameters of the pure solvents are: tetralin 9.5 (cal/ml)“’ *, diphenylmethane 9.6, m-xylene 8.8. Similar comparison may be observed on other scales. The effect of mixing pure solvents of different characters on gas solubility was to be observed in this study.
EXPERIMENTAL
The experimental apparatus has been described (Simnick et al., 1977). It is of the flow type in which the residence time of the fluids in the high tempera- ture zone is kept short in order to reduce chemical reactions. The compressed gas and liquid streams are mixed and heated in a tube in which is fitted a notched spiral ribbon. The heterogeneous fluid mixture is separated in an insu- lated cell maintained at a uniform temperature. The overhead and bottoms streams from the cell are separately sampled for the equilibrium phase compo- sitions. The experimental procedure has been described (Simnick et al., 1977). However, a variation is needed in the present study in the determination of compositions of the ternary mixtures. The liquid collected from either cell effluent upon cooling and reduction of pressure was analyzed in a gas chroma- tograph to determine the relative composition of the two hydrocarbons. The composition of hydrogen was determined from the volume of gas collected at the same time with the liquid. Minor corrections were applied to account for the hydrocarbons vaporized into the hydrogen gas, and for the hydrogen dis- solved into the liquid at ambient conditions.
Gas chromatographic determination of the relative composition of the two hydrocarbons in a liquid sample was based on calibrations with samples of known compositions prepared by mixing weighed quantities of the pure com- ponents. Ten mixtures of tetralin + diphenylmethane and ten of tetralin + m-xylene were prepared by weighing. A calibrating equation containing two empirical constants was fitted to the data of each binary system and used for the determination of compositions of the unknowns. The maximum deviation of the calibrating data from the fitting equation was 0.15 mole% and the RMS 0.06 mole% for mixtures of tetralin and diphenylmethane. The maxi- mum was 0.30, and RMS 0.14 for tetralin and m-xylene.
All materials used in this work were the same as in our previous studies of the binary mixtures. Hydrogen was supplied from Air Products Company with a minimum purity of 99.95%. The hydrocarbons were purchased from Aldrich Chemical Company with a reported purity of 99%. The claimed purity was confirmed by our gas chromatographic analysis to be 99%+. Samples of the solvents collected from both cell effluents were not recycled to the feed.
* 1 (cal/ml)1’2 = 2.046 X lo3 (J/m3)1/2.
37
RESULTS
Gas-liquid equilibrium in the system hydrogen + mixed solvent of tetralin and diphenylmethane was measured at four temperatures from 190 to 430°C and four pressures from 20 to 250 atm. The hydrogen + tetralin + m-xylene system was studied at temperatures from 190 to 310°C and in the same pres- sure range. The mixed solvents are all approximately equi-molal in the organic compounds studied.
Table 1 summarized the experimental results on hydrogen + tetralin + diphenylmethane and Table 2 on hydrogen + tetralin + m-xylene. Duplicate samples were taken from each effluent stream from the cell at a fixed tempera- ture and pressure. The duplicates generally agree to within 2% in the mole frac- tion of hydrogen. A number of duplicate runs were made at some conditions of temperature and pressure and the results are shown in Table 1 as separate entries to give an indication of the reproducibility of the experiments.
Figure 1 shows a plot of the K-values of hydrogen in tetralin + diphenyl- methane at 188°C as a function of mole fraction of tetralin in the liquid on a hydrogen-free basis at various pressures. The binary mixture data of hydrogen in the pure solvents that are needed for this figure are taken from previous work of this laboratory. Within experimental uncertainties of the data a linear relationship is obtained. Similar results are obtained from the same mixture
3 0 0.2 0.4 0.6 0.8 1.0
XT
Fig. 1. K-values of hydrogen in tetralin + diphenylmethane at 188OC.
TA
BL
E
1
Sat
ura
ted
equ
ilib
riu
m
phas
e co
mpo
siti
ons
and
K v
alu
es
for
the
hyd
roge
n
+ t
etra
lin
+
dip
hen
ylm
eth
ane
syst
em
~ --
03
P
(at
m)
XH
t A
188
%
189.
3 20
.2
0.01
188
188.
0 20
.3
0.01
171
188.
0 20
.3
0.01
168
188.
2 50
.0
0.02
94
188.
1 15
0.7
0.08
28
187.
9 24
9.0
0.12
92
t ;
268%
26
8.4
19.7
0.
0145
7 26
8.4
50.4
0.
0398
26
8.4
50.4
0.
0388
26
8.3
150.
3 0.
1195
26
8.3
150.
3 0.
1147
26
8.3
150.
3 0.
1186
26
8.4
249.
0 0.
1790
26
8.4
249.
0 0.
1688
XT
0.48
66
0.50
16
0.98
15
0.01
532
0.00
320
82.6
0.
0315
0.
0063
9
0.46
84
0.51
98
0.98
18
0.01
462
0.00
355
83.8
0.
0312
0.
0068
3 0.
4688
0.
5195
0.
9820
0.
0143
6 0.
0036
3 84
.1
0.03
06
0.00
698
0.47
68
0.49
38
0.99
19
0.00
642
0.00
162
33.8
0.
0134
7 0.
0032
9 0.
4546
0.
4626
0.
9966
0.
0026
5 0.
0007
8 12
.04
0.00
583
0.00
169
0.43
52
0.43
56
0.99
74
0.00
204
0.00
060
7.72
0.
0046
8 0.
0013
7
0.37
29
0.61
25
0.89
81
0.06
52
0.03
66
61.6
0.
1749
0.0598
0.4396
0.52
05
0.95
31
0.03
34
0.01
345
23.9
0.
0760
0.
0258
0.
4441
0.
5172
0.
9533
0.
0336
0.
0131
3 24
.6
0.07
56
0.02
54
0.41
84
0.46
21
0.98
16
0.01
336
0.00
505
8.22
0.
0319
0.
0109
3 0.
4203
0.
4649
0.
9801
0.
0143
8 0.
0055
1 8.
54
0.03
42
0.01
186
0.42
08
0.46
05
0.98
06
0.01
404
0.00
537
8.27
0.
0334
0.
0116
7 0.
3885
0.
4325
0.
9865
0.
0096
4 0.
0038
3 5.
51
0.02
48
0.00
885
0.39
10
0.44
02
0.98
60
0.00
995
0.00
403
5.84
0.
0255
0.
0091
5
__-
XD
Y
H
YT
Y
D
KH
KT
KD
t& 348%
348.5
30.3
348.5
20.3
348.4
50.4
348.4
50.4
348.3
150.0
348.3
150.0
348.3
249.7
348.3
249.7
348.3
249.1
t;42B°C
427.9
29.8
427.9
29.8
428.0
30.5
421.6
49.8
427.6
49.8
427.9
149.0
427.9
149.0
427.9
249.7
427.9
249.7
427.9
249.7
0.01515
0.448
0.537
0.598
0.255
0.1469
39.5
0.569
0.274
0.01513
0.445
0.540
0.59
7 0.255
0.1480
39.5
0.572
0.274
0.0486
0.445
0.506
0.822
0.1139
0.0642
16.91
0.256
0.1268
0.0486
0.439
0.512
0.819
0.1160
0.0650
16.85
0.264
0.1268
0.1444
0.417
0.439
0.927
0.0476
0.0253
6.42
0.1142
0.0576
0.1432
0.417
0.440
0.925
0.0489
0.0261
6.46
0.1173
0.0593
0.229
0.372
0.399
0.949
0.0329
0.01818
4.15
0.0884
0.0456
0.225
0.373
0.402
0.951
0.0316
0.01740
4.23
0.0846
0.0433
0.228
0.366
0.406
0.949
0.0326
0.01842
4.16
0.0892
0.0454
0.01920
0.446
0.534
0.251
0.421
0.328
13.05
0.943
0.614
0.01912
0.446
0.535
0.252
0.420
0.328
13.16
0.941
0.614
0.0212
0.409
0.570
0.274
0.376
0.349
12.95
0.920
0.613
0.0539
0.428
0.518
0.497
0.282
0.221
9.21
0.660
0.427
0.0538
0.428
0.518
0.495
0.263
0.223
9.18
0.661
0.429
0.202
0.392
0.406
0.761
0.1397
0.0993
3.76
0.357
0.245
0.203
0.393
0.405
0.760
0.1405
0.0993
3.75
0.358
0.245
0.328
0.311
0.361
0.828
0.0947
0.0773
2.53
0.305
0.214
0.316
0.316
0.368
0.835
0.0908
0.0742
2.64
0.267
0.202
0.321
0.313
0.365
0.835
0.0909
0.0745
2.60
0.290
0.204
TA
BL
E
2
Sat
ura
ted
equ
ilib
riu
m
phas
e co
mpo
siti
ons
and
K v
alu
es
for
the
hyd
roge
n
+ t
etra
lin
+
m-x
ylen
e sy
stem
_
t (“
C)
P
(atm
) X
H
XT
X
M
YH
Y
T
YM
K
H
t L
189%
189.
0 19
.5
0.01
30
0.49
7 0.
486
0.89
2 0.
0204
0.
0872
68
.64
189.
0 19
.5
0.01
30
0.49
8 0.
486
0.89
4 0.
0192
3 0.
0868
68
.76
189.
3 50
.0
0.03
21
0.48
8 0.
479
0.95
2 0.
0082
3 0.
0394
29
.14
189.
3 50
.0
0.03
36
0.48
6 0.
480
0.95
5 0.
0078
5 0.
0370
28
.46
189.
2 14
9.7
0.09
19
0.46
1 0.
447
0.97
8 0.
0034
8 0.
0184
10
.64
189.
2 14
9.8
0.09
27
0.45
5 0.
453
0.97
8 0.
0034
5 0.
0183
2 10
.55
189.
2 25
0.2
0.14
61
0.43
2 0.
422
0.98
3 0.
0025
7 0.
0148
9 6.
73
189.
2 25
0.2
0.14
63
0.43
4 0.
420
0.98
2 0.
0026
9 0.
0152
2 6.
72
t 4
229%
22
9.5
20.0
0.
0134
2 0.
599
0.38
8 0.
796
0.05
94
0.14
45
59.3
229.
5 20
.0
0.01
337
0.59
8 0.
389
0.79
7 0.
0598
0.
1437
59
.6
229.
7 50
.5
0.03
68
0.55
1 0.
412
0.90
7 0.
0237
0.
0688
24
.7
229.
7 50
.5
0.03
69
0.54
4 0.
419
0.90
9 0.
0232
0.
0674
24
.6
229.
5 14
9.4
0.10
76
0.49
5 0.
397
0.95
8 0.
0102
1 0.
0316
8.
90
229.
5 14
9.4
0.10
79
0.49
8 0.
394
0.95
9 0.
0098
6 0.
0309
8.
89
229.
4 24
9.7
0.16
65
0.46
7 0.
366
0.96
9 0.
0074
9 0.
0239
5.
82
229.
4 24
9.7
0.16
89
0.46
8 0.
364
0.96
8 0.
0075
0 0.
0240
5.
73
KT
K
M
0.04
11
0.17
94
0.03
87
0.17
89
0.01
685
0.08
22
0.01
615
0.07
71
0.00
756
0.04
12
0.00
759
0.04
05
0.00
594
0.03
53
0.00
620
0.03
63
0.09
92
0.37
3 0.
1000
0.
370
0.04
31
0.16
7 0.
0427
0.
1611
0.
0206
0.
0795
0.
0198
2 0.
0783
0.01
603
0.06
53
0.01
604
0.06
61
t G
270°
C 26
9.6
269.
6 26
9.5
269.
5 26
9.5
269.
5 26
9.5
269.
5
t ;
309%
30
9.3
309.
3 30
9.2
309.
2 30
9.5
309.
5 30
9.2
309.
2
19.5
0.01255 0.604
0.384
0.589
0.1394
0.272
46.9
0.231
0.707
19.5
0.01247 0.603
0.384
0.59
8 0.1391
0.263
48.0
0.231
0.683
50.0
0.0407
0.522
0.437
0.813
0.0541
0.1327
19.96
0.1037
0.304
50.0
0.0412
0.521
0.438
0.813
0.0538
0.1332
19.74
0.1032
0.304
149.1
0.1265
0.453
0.420
0.922
0.0211
0.0570
7.29
0.0465
0.1358
149.1
0.1253
0.448
0.427
0.920
0.0215
0.0587
7.34
0.0479
0.1373
249.7
0.1987
0.419
0.382
0.940
0.01642 0.0433
4.73
0.0392
0.1133
249.7
0.1993
0.423
0.378
0.941
0.01605 0.0425
4.73
0.0380
0.1124
19.9
0.00
986
0.645
0.345
0.352
0.284
0.363
35.7
0.441
1.053
19.9
0.00
989
0.640
0.350
0.357
0.275
0.368
36.1
0.430
1.051
49.9
0.0432
0.581
0.376
0.691
0.1201
0.189
16.00
0.207
0.503
49.9
0.0430
0.582
0.375
0.687
0.1224
0.1907
15.98
0.210
0.508
149.6
0.1459
0.484
0.370
0.859
0.0500
0.0911
5.89
0.1031
0.246
149.6
0.1459
0.484
0.370
0.860
0.0493
0.0903
5.90
0.1020
0.244
249.6
0.232
0.434
0.335
0.900
0.0356
0.0644
3.88
0.0821
0.1925
249.6
0.231
0.434
0.335
0.899
0.0361
0.0649
3.90
0.0833
0.1936
42
system at other temperatures where a like comparison is possible. The results for hydrogen in tetrahn + m-xylene mixtures are also similar.
Henry constant of hydrogen in a mixed solvent is defined by
(1) where the fugacity of hydrogen fH is given by
fH= GHPY H (2)
The fugacity coefficient 4n is computed from Chueh and Prausnitz’s modified Redlich-Kwong equation of state for the equilibrium vapor mixture. The con- stants in the equation have been generalized by Yao et al. (1978) for hydro- gen-hydrocarbon mixtures.
The precise compositions of the liquid solutions that correspond to the Henry constant values determined in Figs. 2 and 3 remain to be determined. While the liquid feed to the equilibrium apparatus was always almost exactly equi-molal in composition, the equilibrium liquid phases varied in composi-
C”“”
18a'C w 1600
cl
_I
266
0 1290
I
< 348
,I
800
00 0 0.1 0.2 xii
Fig. 2. f&xH versus XH for hydrogen + tetralin + diphenylmethane system.
43
1701
1501
1301
f d
llO(
901
70(
3-
3-
/
3-
,
3-
/
3-
r(
II- 0 0.1 0.2 0.3
xH Fig. 3. f&H versus xH for hydrogen + tetralin + m-xylene system.
0.6 I , I I I
0.4 I I , I 0 0.1 0.2 0.3
xH
Fig. 4. Extrapolation of hydrogen-free solvent composition to XH + 0 for the hydrogen + tetralin + diphenylmethane system.
0.41 I I I I 0 0.1 0.2 0.3
Xki
Fig. 5. Extrapolation of hydrogen-free solvent composition to XH + 0 for the hydrogen + tetralin + m-xylene system.
tion on a hydrogen-free basis due to partial vaporization of the liquid feed, and were always enriched in the heavier component.
Figure 4 shows the extrapolation of the hydrogen-free mole fraction com- position of the solvent to xH = 0 for the hydrogen + tetralin + diphenylmeth- ane system. The extrapolation is carried out in the figure for two tempera- tures. The same procedure is used for the other temperatures, and for hydro- gen + tetralin + m-xylene (Fig. 5). In this way we obtain the precise composi- tions of the liquids corresponding to the various values of Henry constant of hydrogen. The results are summarized in Table 3.
Figure 6 shows the Henry constant of hydrogen as a function of the mole fraction composition of the liquid solvent tetralin + diphenylmethane. The pure solvent results are taken from previous work. Figure 7 shows similar results for the solvent tetralin + m-xylene. A linear relationship is observed in all cases. The largest deviation from linearity is obtained for hydrogen in tetralin + m-xylene at 309°C where the deviation is still within the uncertainty of the data.
TABLE 3
Henry constant of hydrogen and composition of mixed solvent at various temperatures _____-__
t (“C) XT H~(atm)
Hz + tetralin + diphenylmethane 188 0.491 1660 268 0.445 1184 348 0.455 800 428 0.455 432
Hz + tetralin + m-xylene 189 0.504 1344 229 0.592 1168 270 0.560 924 309 0.637 752
> 0 188 “C <
A 268 E 3 <
yooo- 348
”
c
500-
300< 0 0.2 0.4 0.6 0.8 1.0
xT
Fig. 6. Henry constant of hydrogen versus XT in tetralin + diphenylmethane mixtures.
Fig. 7. Henry constant of hydrogen versus XT in tetralin + m-xylene mixtures.
We conclude that the solubility behavior of hydrogen in the mixed solvents studied is simply related to the behaviors in the pure component liquids, and can be completely predicted from information on the latter. The experimental result shows an absence of any special effect of mixing of solvents on hydro- gen solubility. The same observation is likely valid for solvents similar to those studied here.
The present conclusion lends support to the study of gas solubility in pure component liquids with the ultimate objective of applying the results and cor- relations to complex oils and oil fractions.
ACKNOWLEDGMENT
This research was funded by the Electric Power Research Institute through research project RP367.
LIST OF SYMBOLS
f = fugacity (atm) H = Henry constant (atm) K = vaporization equilibrium ratio E y/x p = pressure (atm) t = temperature (“C) x = mole fraction in liquid phase y = mold fraction in gas phase @ = fugacity coefficient
46
Subscripts
D = diphenylmethane ii = hydrogen M = m-xylene T = tetralin
REFERENCES
O’Connell, J.P., 1971. Molecular thermodynamics of gases in mixed solvents. AIChE J., 17 658-663.
Simnick, J.J., Lawson, C.C., Lin, H.M. and Chao, K.C., 1977. Vapor-liquid equilibrium of hydrogen/tetralin system at elevated temperatures and pressures. AICHE J., 23: 469- 476.
Simnick, J.J., Liu, K.D., Lin, H.M. and Chao, K.C., 1978. Gas-liquid equilibrium in mix- tures of hydrogen and diphenylmethane. Ind. Eng. Chem. Proc. Des. Develop., 17: 204-208.
Simnick, J.J., Sebastian, H.M., Lin, H.M. and Chao, K.C., 1979. Gas-liquid equilibrium in mixtures of hydrogen + m-xylene, and + m-cresol. J. Chem. Thermodynamics, in press.
Yao, J., Sebastian, H.M., Lin, H.M. and Chao, K.C., 1978. Gas-liquid equilibria in mix- tures of hydrogen and l-methylnaphthalene. Fluid Phase Equilibria, 1: 293-304.
