rY
Vapor Liquid Equilibria in HYDROGEN WITH ETHYLENE, ETHANE,
PYLENE,
RICH.LIRD B. KILLHAa41S AND DONALD L. KAT-Z C'niversity of Michigan, I n n ,lrbor, -3Tich.
EYERAL recent, papers have revien-ed t h e literature on
K r t t z ( 3 ) . 3Iodifications of the equipment included a couiit('rcurrent heat esclmnger for the vapors leaving and entering tiiv cell. An electlomagnetic pump circulated the vapor. Temper:\ture Tvae measured hy a triplcjunct,iori copper-conrtiliitari thermocouple in rt ne11 v-it,liiri
phase behavior of hj-drocarbon systems cont,aining hydrogen. Sage and coxvorkera presented the hydrogen-propane sps-
ix-ing the difference method Ivith a nitrogen vapor p ~ c SUI" t,lierrnometer :md so carhon dioxide ( 2 ) . Pressures ryere measured bj. i? series of three preisure gage+, which were calibrated periodically with a dead weight tester. Temperatures are helieved to be within 1 1 .0" F. f r o m t h e t r u e v a l u e s at, -300" F. and 1 0 . l o P. at r o o in t einp e r a t u I' e . Prwsure3 are believed to be witliiri ~ k 0 . 5 7of~the true preFpure. Samples of the liquid phasc were taken from the cell through a sniall tube which was purged before securing the sample as a vapor phase at rooni conditions. Vapor samples were talcen from
_ _ -~ - - - _ _
~
_ _ _ __
____ __
I 1- __-
0
4
8
12
16
20
MOL
Figure 1.
24 28 32 36 PERCENT HYDROGEN IN LIQUID
40
44
56
52
48
3Iole Per Cent Hydrogen i n Liquid Phase, Hydrogen-Ethylene Sjstem
tern from 10" to 190" F. during the course of this research ( 4 ) . Aroyan and Ilatz determined t,he phase composit,ionP for the hydrogen-butane ten1 from 70" to -200 and 300 t o 8000 pounds per square inch ( 3 ) . This research follovied the general procedures of Aroyan for four vr-ittiethylene, ethane, propylei;e, and propane. Three t e r n a r y mixtures were studied at -100" k'. arid two preasuree. EQUIPMENT ANI)
PROCEDURES
Equilibrium between vapor and liquid phaae? was obt,ained hy circulat,ing vapor through the liquid phase in t h e steel equilibrium cell described by Aroyan and
-T-7--itoo 44
1 48
Figure 2.
!
52
-
~-I
/ _ _ _
I 56
60
64
!
--
-
I
,
---
1-
7
-
I
72 76 80 84 M a . PERCENT HYDROGEN IN VAPOR 68
---
I 88
92
t
1
96
100
Mole Per Cent H5drogen i n Vapor Phase, Hydrogen-Ethylene System 2.512
December 1954
INDUSTRIAL AND ENGINEERING CHEMISTRY
2513
PRESSURE, PSIA
Figure 4.
Equilibrium Constant for Ethylene, Hydrogen-Ethylene System
10,000
\
, 9000 8,000
I
11
,
-
11,
PRESSURE, PSIA
the circulating vapor line and transferred to a 220-mI. vapor density bulb for determination of density at a known temperature and presure. Compositions were obtained by interpolating between the density of the pure constituents. For each charge to the cell, a sample of the hydrocarbon liquid was obtained and the vapor density determined for t h a t series of measurements. The value for hydrogen and average values found for the hydrocarbons are given in Table I. If the density of the hydrocarbon charge deviated by more than 0.10% from the value in Table I, the charge was discarded. When the hydrocarbon concentration in the vapor phase was below 2 mole %, the samples were analyzed by means of a double-beam infrared spectrometer. The accuracy of the spectrometer was within 3 ~ 3 %of the hydrocarbon present or 0.015 mole %, whichever is larger. The gas deneity analyses are believed to be correct within i O . l % of the reported mole per centages for the ethane and ethylene systems and within 5~0.06%for the propane and propylene systems.
OF PURE GASESUSED TABLE I. DENSITY
Density, G./Liter, 77' F. and 7G0 M m . Gas Hydrogen Ethylene Ethane Propylene Propane
Figure 5.
Pressure-Temperature Diagram, HydrogenEthylene System
HZ
0.0823 1.1510 1.2388 1,7382 1.8310
HYDROGEN-ETHYLENE SYSTEM.The hydrogen supply was reported to be 99.9% pure water-pumped hydrogen, and infrared analyses found no hydrocarbons present. Ethylene was analyzed by the supplier with a mass spectrometer as 99.6% ethylene. All gases transferred to the equilibrium cell were passed through a train under pressure, which contained magnesium perchlorate and Ascarite.
Six isotherms were studied at temperatures from 0" down to -250" F. The first run was made a t 250 pounds per square inch absolute with successive pressures at 500, 1000, 2000, 4000, and 8000 pounds per square inch unless the critical pressure was reached. I n these cases, an equilibrium was determined a t some pressure slightly below the critical pressure. Some of the equilibria were determined by increasing pressure, while a few were obtained a t decreasing pressures. Example data for the 100' F. isotherm are given in Table 11. Runs 30 and 31 made a t the beginning of the investigation, and runs 381 and 382 made a t the end, differ by not more than 0.25 mole % in phase compositions.
-
PRESSURE, P S l A
2514
December 1954
INDUSTRIAL AND ENGINEERING CHEMISTRY
2515
TABLE 11. EXAWPLE OF EXPERIMENTAL DATAFOR HYDROGENETHYLENE SYSTEM AT - 100' F. Run No. 222 223 379 380
Pressure Lb./Sq. Inch Abs. 250 250 260 250
Composition, Mole % Hz Liquid Vapor phase phase 0.85 68.18 0.81 68.14 0.79 68.26 0.74 68.30
KHZ
KCiHi
84.2
0.320
41.3
0.189
21.2
0.121
10.8
0.0924
Av. 0 . 8 1 Av. 68.25 22 23 224 225 20 21 226 227
Av.
1.96 81.40 1.94 81.51 1.98 81 5 1 2.01 81.38 1 . 9 7 A v . 81.46
Av.
4.20 88.45 4.13 88.56 4.10 88.30 4.21 88,42 4.16 Av. 8 8 . 4 3
500 500 500
600
1000 1000 1000 1000
18 19 228
2000 2000 2000
8.47 8.46 8.50 AY. 8 . 4 8 Av.
91.76 91.48 91.41 91.55
30 31 381 382
4000 4000 4000 4000
15.90 16.22 16.13 16.15 Av. 16.10 Av.
92.71 92.46 92.60 92.63 92.60
383 384
8000 8000
30.78 30.78
89.78 89.77 89.71
Av. 30.78
Figure 10.
Pressure-Temperature Diagram, HydrogenEthane System
V i S d '3LlnSS3Lld
5.75
0.0883
2.91
0.148
2516
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 46,No. 12
..
PRESSURE, P S l A
Figure 1.5- Pressure-Temperature Diagram, Hydrogen-Propylene System
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_,
PRESSURE, P S l A
2517
2518
Vol. 46, No. l2
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
TEMPERATURE, F'
Figure 20.
Pressure-Temperature Diagram, Hydrogen-Propane System
At low temperaturea, as many as 8 hours were required t o obt'ain equilibrium, Successive samples of liquid were analyzed uiitil 110 further change in composition was observed before a value was reported. The liquid phase compositions are given in Figure 1 and the vapor phase is given in Figure 2. The equilibrium constants, mole fraction in vapor divided by mole fraction in liquid, for hydrogen a,re in Figure 3 and for ethylene in Figure 4. The pressure-temperature plots ehoning bubble points and some dew points are on Figure 5 . Except at' l o a pressure, hydrogen has a reversed solubility-Le., it decreases in solubility with reduction8 in temperature. HYDROGES-ETHbSE SYSTEX. Pure grade ethane analyzing 99.7 mole % ' ethane was furnished through the courtesy of the Phillips Petroleum Co. Six isotherms froin 50" to -275" F. were determined at pressures from 250 to 8000 pounds per square inch absolute. The phase compositions are given in Figures 6 and 7, the equilibriunl constants in Figure 8 and 9, and thc pressuretemperature projectioiis in Figure 10. €1Y D R O G E N-PR o PITL E ri E SYSTEM. Propylene was reported to be bettjer t)han 99.0 mole % pure. Seven isotherms were determined froin 75' to
TABLE Iv. Tenig.,
F.
230
SMOOTHED EXPERIMESTAL D.kT.4
Pressure, Lb. per Square Inch Absolute 1000 2000 4000
500
HYDRO G E s - E , r H l' L E S E
56.0 0,764 84.2 0.320 123 6
0.0780 147 0.0408 188 308
8000
SYSTE>l
17.1 0.863 23.1 0.660 28.2 0.462
8.10 0 . 600 11.25 0.431 14.4 0.284
3.94 0.496 5.50 0.338 7.33 0.214
2.15 (3000)" 0.581 (3000) 2.43 0.408
1 . 4 2 (3800) 0 . 7 6 1 (3900) 1 . 5 3 (5000)
3.51 0 236
41.3 0.189 62.0 0,0500 76.1 0.0268 96.4
21.2 0.121
10 8 0 092.1
L73 0.0883
1 . 5 0 (7000) 0 . 543 (7000) 2.91 0.148
31.8 0,0346 38.6 0.0201 50.3 82.7
1G.j 0 0293
8.82 0.0308
0.0456
20.2 0.0179 20.6
0.0212 14.60
44.8
28.5
159
10.9
0 . 6 5 2 (5000)
4.05 6.25 0.0328 8.76
18.7
HYDROGEX-ETIIASE SYSTEM 12.1 0.922
48.8 0.896 75,4 0.424 101.2 0,180 124.4
0.0362 160 0.00462 238 320 a
24.4 0.534 36.8 0.246 40.0 0,0850 62.2 0.0206 83.0 0.00314 129 179
6.45 0.657 12.2 0.347 18.1 0,148 24 3 0.0543 31.3 0.0143 43.2 0.002Cili
70.8 100
Yalnes i n Iiarentheses show pressure for indicated K
3.21 0.567
6.12 0.264 '3.05 0.113 12.4 0 0432 16.3 0.0127 23.G
2 . 1 3 5 (2800) 0.632 (2500) 2.82 0.296
1.853 l.6000) 0 . 6 1 6 (4,000)
4.49 0.116
0.210
6.35 0.0463
3.38 0.07x
40.0
8 75 0,0157 13.1 0,00432 22.9
.57. -1
33.3
0.00272
2.17
4.86
0.0277 7.45 0.00984 13.5 1 0 .8
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
December 1954
2519
TABLE111. TERNARY EQUILIBRIUM DATA _1000 Lb /Sq Inch Abs_ 1Iole
Mole
liquid 4.1 45.1 50.8 3.1 55.1 41.8 2.8 55,0 42.2
vapor 91.83 5.32 2.85 93.41 6.22 0.37 99.26 0.44 0.30
'b.
Component Hz
CZHI CzHa
H2 CzH4 CaH5 Hz CaH5 CaHs
%
K 22.4 0.118 0.0660 30.1 0.113 0,0089 35.4 0.0080 0.0071
8000 Lb./Sq Inch ~ Abs mole Mole
%
liquid 30.7 35.5 33.8 21.7 37.9 40.4 18.1 45.3 36.6
%
vapor
K
93.29 5.11 2.60 95.01 4.30 0.65 99.07 0.52 0.41
30.3 0.144 0,0770 4.38 0.113 0.0161 5.47 0.0115 0.0112
-250' F. with pressures from 250 to 8000 pounds per square inch absolute. The phase compositions are given in Figures 11 and 12, the equilibrium constants in Figures 13 and 14, and the pressure-temperature diagram is given in Figure 15. H Y D R O G E X - P R O P A X E SYSTEM.Pure grade propane was furnished with a reported purity of 99.8 mole %. Nine isotherms from 75" to -300" F. were determined v i t h pressures from 250 to 8000 pounds per square inch absolute. The phase compositions are given in Figures 16 and 17, the equilibrium constants in Figures 18 and 19, and the pressure-temperature diagram in Figure 20.
~
Figure
21.
Correlation of Ry~rogen-I-Iydrocarbon Systems
TERNARY DATA
CORRELATION OF D A T i
Mixtures of hydrogen, ethylene, and ethane; hydrogen, ethylene, and propylene; and hydrogen, propylene, and propane were brought to vapor liquid equilibrium a t - 100' F. and pressures of 1000 and 8000 pounds per square inch absolute. The vapor phases were analyzed by the infrared spectrometer, and the liquid phase saniples mere submitted to a commercial laboratory for analysis by a mass spectrometer. The data are given in Table 111.
Within individual binary systems, plots of the product of pressure times the equilibrium constant were made against both pressure and temperature to test the consistency of the data. r2n occasional deviation up to 0.3% was found with phase compositions low in either constituent. Otherwise the reported compositions agreed with smoothed values. Table IV gives a summary of the smoothed experimental data for the binary systems. The smoothed data do not differ from the experimental data by more than 0.3 mole % at any point. Aroyan developed a correlation for hydrogen equilibrium constants involving the reduced temperature of the hydro~goon carbon in the binary. A modified version of this correlation, including the data in this paper, is given on Figures 21 1.81 and 22. In a binary system, the hydro0.303 gen equilibrium constants are obtained 2.31 0.171 by computing the reduced temperature 3.20 (temperature divided by critical tempera0.0722 ture of the hydrocarbon, TR)and finding 4.31 the constant from Figure 21 a t the de0.0319 5,93 sired pressure. For all systems except 0.0116 the hydrogen-butane system, a multi8.63 plier, F , from Figure 22 corrects the 13.8 values from Figure 21. For ternary or 28.6 more complex mixtures, the hydrogen equilibrium constant may be computed as an average value. The constants for 1.825 0.264 hydrogen are obtained to correspond t o 2.27 each of the hydrocarbons in the mixture. 0.151 These values are averaged arithmetically 3.00 0.0029 based on the molal concentration of the respective hydrocarhon in the liquid 3.98 0.0275 phase. Table V shows a comparison of 5.11 the predicted and experimental equilib0.0111 rium constants for hydrogen in ternary 7.00 0.00324 mixtures. 10.8 Considerable effort wa3 spent with 19.5 other correlating methods. Figure 23 45.7 illustrates the behavior of the hydrogen e u u i l i b r i u m constants in the four binaries a t 4000 pounds per square inch.
TABLE IV. (Continued) Temp,
F.
Pressure, Lb. per Square Inch Absolute 1000 2000 4000
260
500
46.0 0 688 57.0 0.516 79.4 0.2% 112 0.0736 156 0.0224 201 306 596
24.9 0,404 30.9 0,286 40.7 0.126 57.6 0.0444 79.6 0.0130 103 159 318
52.0 0.592 60.8 0.415 78.4 0.175 100 0.0600 123 0.0180 158 0.00338 214 330 664
26,O 0.348 30.4 0.233 39,4 0,0952 51.0 0.0336 63.8 0.00992 82.0 0,00198 114 177 366
HYDROQES-PROPYLENB SYSTEM +75 K H X KCaHs
+60 K H Z KC3H6
0 KHZ
KCaH6
-50 K H Z KC386
-100 K H Z KCaHs
- 150 KH2 -200 K H ~ 250 K H Z
-
13.4 0.248 16.1 0.175 21.1 0.0765 29.2 0.0292 40.2 0.0082 52.9 82.8 165
7.12 0.176 8.39 0.125 11.0 0.0550 14.7 0.0220 20.3 0.00665 27.1 43.2 89.0
3.67 0.166 4.38 0.113 5.82 0.0500 7.66 0.0234 10.4 0.00803 14.7 23.2 48.5
RYDRGGEN-PROFANE SYSTEM 13.2 0.212 15.3 0.144 19.8 0.0621 26.0 0.0220 32.9 0.00710 43.6 0.00133 61.3 96.1 204
6.85 0.149 7.85 0.103 10.1 0.0476 13.3 0.0184 16.9 0.00590 22.5
0.00108 33.3 55.5 120
3.62 0.144 4.15 0.0977 5.40 0.0427 6.95 0.0180 9.08 0.00638 12.1 0.00141 18.6 32.3 71.9
2520
INDUSTRIAL AND ENGINEERING CHEMISTRY
(
60\
\
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Vol. 46, No. 12
FIG. 23 EQUILIBRIUM CONSTANTS
2r:---, -,-7-y\,1
1
____-
0.2I
I
I 0.5
0.4
I
1
0.6 0.7 0.8 REDUCED TEMPERATURE, TR
Figure 22.
I
0.9
I
IO
Correlation Factors
I -300
-250
-200
-IS0 -100 -50 TEMPERATURE, 'F
0
I
+SO
+IO0
Because of the closeness of the properties of the pure conptituents, such as critical temperature arid 1)oiliiigpoints, no simple relation*hip between these properties and the variat,ion in equiliisriuiii constants can be iourid which would apply a t all temperatures. -kt lo^ temperatures, hydrogen is less soluble in t,he oiefiii 1iyilt.ocarbons than the paraffins; at higher temperatures the re ie true. At present, the procedure recommended for obtaining hydrogen equilibrium constants is t o interpolate bet'n-een the data when possible, recognizing t h e molecular weight and structure of the hydrocarbon in t h e liquid phase. Figures 21 arid 22 also inny be used, as indicated above. T h e reversed solubility for hydrogen continues to -300' F. In fact, hydrogen solubility decreases very rapidly as the freezing point of the hydrocarbon is approached. i2t high concentrations of the hydrocarbon in the vapor phase, normal solubility must occur a t all temperatures. At the vapor pressure of t h e solvent, hydrogen solubility is zero. h t the same pressure and a lower temperature, there is a solubility for t h e hydrogen. It follows that, there is at least a narrow region of normal solubility a t pressures just above the vapor pressure curve of t'he hydrocarbon. T h e hydrocarhon equilibrium constants in hydrogen systems at high pressure are l o ~ w t'haii r they are when the more volatile component is methane. T h e pressures at which the constants converge to unity are much higher for t h e hydrogen binaries than for the methane binarier. Figurc 24 compares thcse convergences and equilibrium constari ts for the binaries Kith propane as the common conetituent ( I ) . Figure 24. Equilibrium Constants for Binary Systems Methane-Propane ( I ) and Hydrogen-Propane a t 0 " F.
ACKSQ'U;'LEDG&lENT
The authors wish to acknowledge t h e pure ethane and propane donated b y t h e Phillips Petroleum Co. This work was macle poisible by a fellowship granted by T h e Visking Corp. LITERATURE CITED
TABLEJT.
COMPARISON O F PREDICTED ASD EXPERIXLXTAL ~
