INDUSTRIAL AND ENGINEERING CHEMISTRY
July, 1942
ficiently precise to permit of a superimposition of charts, with abscissas in alignment, to aid in Selecting the correct hydrocarbon type for use with a given resin. It is thus hoped that comparative thinning efficiencies, estimated directly from such superimpositions, may prove helpful to formuIators.
Acknowledgment
885
Literature Cited (1) Baldeschwieler, E. L., Morgan, M. D., and Troeller, W. J., IND. ENQ.CHEM.,ANAL.ED..9.540 (1937). (2) Baldeachwieler, E. L., Troeller,'W. J., and hiorgan, M. D., Ibid., 7, 374 (1935). (3) McArdle, E.H., and Baldeschwieler, E. L., Ibid.. 13,301 (1941). (4) Philadelphia Paint and Varnish Production Club, Federation of Paint and Varnish Production Clubs, Tech. Proc., 1939, 115.
w.
before the Division of Paint, Varnish, and Plastics Chemistry Thanks are due L, Rossin of Reichold chemicals, I ~ ~ . PRESENTED a,t the 102nd Meeting of the AMERICAN CHEMICAL EOCIETY, Atlantic City, who assisted in the selection of resins and supplied the samples. N. J.
P-V-T-x Relations of the System Propane-Isopentane J
WILLIAM E. VAUGHAN AND FRANK C. COLLINS Shell Development Company, Emeryville, Calif.
An experimental study has been made of the P-Y-T-x relations of five mixtures of propane and isopentane in the temperature range 0' to 300' C. and in the pressure range 2 to 80 atmospheres. The two-phase and the critical regions have been carefully defined. The data, which are presented in tabular and in graphical form, have been used to calculate the phase equilibrium constants.
T
HE study of the phase behavior of pure hydrocarbons and their mixtures has been greatly extended in the recent past, as a result of the increasing importance of such data to both the field production and refinery engineers. The following report presents in detail data obtained from measurement of the FV-T relations of five different mixtures of propane and isopentane. The primary data consist of pressure-volume relations measured isothermally a t 25" intervals from 0" to 300" C. in a pressure range from about 2 to 80 atmospheres. Supplementing these are other data obtained to define clearly the critical region. It is hoped that the present data will eventually lend themselves to development of a generalized system for predicting volumetric and phase behaviors. P-Y-T Apparatus The apparatus described in an earlier publication (9) was employed with a few modifications. It is essentially the type used by Young (11) as modified by Kay ( 4) ; it consists of a steel compressor unit, with mercury as the liquid, on which are mounted glass capillary tubes containing the hydrocarbon samples. The pressures are measured by closed-end nitrogen manometers, also mounted on the compressor block. The attainment of equilibrium conditions was expedited by magnetic stirrers, composed of Alnico alloy, which were manually raised and lowered in the capillaries by directcurrent-actuated solenoids. The volumes of weighed stirrers were calculated from the density determined from a larger sample of the material.
Accurate regulation of temperature was necessary, especially in the critical region. Considerable difficulty was a t first experienced due to the presence of impurities in the refluxing vapor baths and to decomposition of the liquids employed. The higher boiling liquids were later refluxed under nitrogen to minimize decomposition. The following liquids were selected for the various isotherms since they were found to be relatively stable and fairly easy to obtain in a high degree of purity: 0" C., methyl chloride; 25", diethyl ether; 50", acetone; 75", trichloroethylene; loo", methylcyclohexane; 125", chlorobenzene; 150°, bromobenzene; 175", phenol; 200°, tetrahydronaphthalene; 225", quinoline; 250-275 ", a-bromonaphthalene ; 300 ", benzophenone. Special precautions were taken to avoid contamination of the hygroscopic substances with moisture from the atmosphere.
Filling Apparatus and Procedure This apparatus and method were described in some detail (9), and accordingly only the modifications will be discussed. Because of the tendency of isopentane t o dissolve rapidly in stopcock grease, the filling apparatus was so designed as to eliminate stopcocks from the isopentane lines. All-metal packless valves (9) and mercury cutoffs were used to control the flow of isopentane. The compositions of the various mixtures were determined by measuring out calculated amounts of the pure substances from the calibrated gas buret which was accurately thermostated a t 30" C. The densities of propane and isopentane a t atmospheric pressure and 30" C. had been carefully determined, so that accurate calculation of the molal composition and weight of the sample condensed into the capillary was made possible. After filling, mercury was flowed into the inverted capillary over the condensed sample. Then atmospheric pressure was restored in the system, and the tube removed and mounted on the compressor block. Considerable difficulty had been experienced as a result of vaporization of the hydrocarbon upon contact with the warmer mercury. This was overcome by chilling the capillary immediately above the condensed sample with liquid nitrogen so as to freeze the mercury before it flowed into contact with the hydrocarbon sample. The
INDUSTRIAL AND ENGINEERING CHEMISTRY
886
Vol. 34, No. 7
PRESSURE, ATMOSPHERES
FACTOR 2 us. PRESSURE FOR 89.9 MOLE PERCENTISOPENTANE-10.1 MOLEPERCENTPROPANE FIGURE 1. COMPRESSIBILITY
sample was maintained chilled until the capillary was mounted on the compressor unit and the pressure raised. This procedure prevented expansion of the sample with consequent danger of sticking of the Alnico stirrer and entrapment of hydrocarbon bubbles in the bell-shaped lower end of the capillary.
Materials The propane was obtained from a refinery sample which was redistilled in a pressure column a t about 200 pounds per square inch. The material was then redistilled through a Podbielniak-type column. The product boiled at a temperature constant within 0.02' C. A determination of the absolute value of theboiling point wasnotmade. Theliteraturegives -42.2'C. as the boiling point of pure propane (3). The sample was deaerated by successive vaporization, condensation over liquid oxygen, and evacuation of the residual air with a mercury diffusion pump. This was repeated seven times after which the pressure over the sample, while cooled with liquid nitrogen, amounted to only 0.0001 mm. of mercury. TEMPERATURE, 'C. The isopentane was prepared from redisFIQURE 2. BUBBLE POINT-DEW POINT CURVES OF PRESSURE us. TEMPERATURE tilled tertamyl alcohol by first dehydrating with concentrated sulfuric acid to yield tertamylene, distilling the product, and then hysure of 760.0 mm. of mercury. This compares with a value drogenating it to form isopentane. The final product was disof 27.95' C. obtained by both Young and Thomas (18) and tilled in a 44-plate laboratory column, a cut of the distillate Timmermans and Martin (8). Other investigators have being taken at a constant temperature of 27.87' C. a t a pres-
INDUSTRIAL AND ENGINEERING CHEMISTRY
July, 1942
887
TABLE I. COMPRESSIBILITY FACTOR Z FOR UNSATURATED VAPOR 10
c.
5 atm.
Compressibility Factor 2 10 atm., 15 atm. 20 atm. 25 atm. 30 atm. 35 atm. 40 atm. 45 atm. 50 stm. 55 atm. 60 atm. 65 atm. 70 stm. 75 atm. 80 atm.
25 50 75 100 125 150 175 200 225 250 275 300
0.904 0.929 0.946 0.958 0.966 0.974 0.980 0.983 0.986 0.989 0.991 0.993
o:ii9 0.881 0.908 0.927 0.943 0.955 0.963 0.969 0.975 0.979 0.984
50 75 100 125 150 175 200 225 250 275 300
0.918 0.939 0.953 0.964 0.972 0.979 0.983 0.986 0.989 0.991 0.993
O:Sk5 0.897 0.920 0.938 0.951 0.961 0.969 0.976 0.980 0.985
75 100 125 150 175 200 225 250 275 300
0.922 0.944 0.957 0.965 0.972 0.978 0.982 0.986 0.990 0.993
75 100 125 150 175 200 225 250 275 300
0.919 0.939 0.955 0.965 0.973 0.980 0.985 0.990 0.993 0.996
100 125 150 175 200 225 250 275 300
0.924 0.943 0.968 0.967 0.976 0.983 0.987 0.991 0.995
O:i(k7 0.898 0.919 0,935 0.948 0.958 0.967 0.974 0.980
0:&7 0.888 0.915 0.935 0.949 0.961 0.970 0.978 0.985
0:8i4 0.883 0.913 0.933 0.949 0.961 0.971 0.980
... 0:8b 0.852 0.885 0.909 0.928 0.941 0.951 0.960 0.967 0.974
... 0:iia 0.874 0.900 0.921 0.938 0.950 0.960 0.968 0.974
0:t i 5 0.831 0.869 0.896 0.916 0.932 0.945 0.957 0.965
... O:Sb4 0.856 0.890 0.913 0.932 0.947 0.960 0.970
... ... :
0 $44 0.841 0.875 0.901 0.919 0.933 0.945 0.956 0.964
10.1 Mole Per Cent Isopentane-89.9 Mole Per Cent Propane
... ... :
0 fi7
0.795 0.840 0.873 0.897 0.916 0.930 0.944 0.955
... ...
0 644 0.744 0.804 0.845 0.875 0.899 0.917 0.932 0.945
... ... 0 :687 0.767
... ...
9 . .
0.817 0.853 0.882 0.904 0.921 0.935
1 . .
0:lrir 0.728 0.788 0.830 0.865 0.891 0.909 0.925
... ... ...
... ... ...
.. .. ...
...
0: 641 0.684 0.759 0.808 0.848 0.877 0.898 0.916
O:i46 0.637 0.729 0.787 0.830 0.864 0.887 0.906
O:3.k7 0.591 0.698 0.766 0.813 0.849 0.877 0 * 898
20.6 Mole Per Cent Isopentane-79.4 Mole Per Cent Propane 4 . .
0:%4 0.825 0.862 0.892 0.914 0.930 0.944 0.956 0.965
... 0:iis 0.817 0.856 0.884 0.907 0.924 0.939 0.950
... ... 0 :$87 0.839 0.874 0.901 0.922 0.940 0.953
...
...
o:i91 0,844 0.881 0.905 0.928 0.944 0.958
0:6?6 0.769 0.825 0.861 0.892 0.915 0.934
... ...
... ...
... ...
... ...
... ...
o:ii1
0:ibS 0.781 0.829 0.866 0.893 0.914 0.931 0.945
O:f%3 0.736 0.797 0.841 0.873 0.899 0.919 0.935
0:iis 0.687 0.763 0.816 0.854 0.884 0.908 0.926
0:%5 0.635 0.729 0.790 0.834 0.869 0.895 0.917
0.823 0.862 0.891 0.912 0 * 929 0.943 0.955
... 1..
0:iio 0.575 0.695
0.765
0.816 0.854 0.883 0,907
... 1 . .
0:%7 0.512 0.660 0.740 0.798 0.839 0.872 0.898
41.2 Mole Per Cent Isopentane-58.8 Mole Per Cent Propane
... ... ...
... ... ...
... ...
... ...
O:i67 0.543 0.667 0.744 0.797 0.836 0.866 0.890
0: 299 0.499 0.637 0.723 0.781 0.823 0.856 0.883
0..'305 0.464 0.609 0.703 0.765 0.813 0.846 0.875
0'. 315 0.437 0.583 0.683 0.751 0.802 0.837 0.868
0:.!324 0.416 0.561 0.664 0.738 0.791 0.827 0.861
... ...
... ...
... ...
.... *.
... ...
0:2?5 0.458 0.624 0.716 0.781 0.825 0.861 0.890
0'.287 0.420 0.591 0.694 0.765 0.813 0.850 0.881
O'.iD9 0.399 0.561 0.673 0.749 0.801 0.840 0.873
0.392 0.535 0.652 0.732 0.790 0.831 0.866
o:iiz
0:.!326 0.390 0.512 0.631 0.715 0.780 0.825 0.860
...
...
... ...
... ...
... ...
... ...
... ...
... ...
... ...
... ...
... ...
... ...
... ...
...
0.761 0.813 0.852 0.881 0.904 0.921 0.936
0:&7 0.769 0.819 0.856 0.883 0.904 0.921
o:ii1
0:iig 0.671 0.749 0.803 0.840 0.870 0.893
o:4iz
0:3b8 0.561 0.677 0.751 0.800 0.838 0.868
0:283 0.504 0.641 0.724 0.781 0,822 0.855
0:2i9 0.454 0.605 0.698 0.762 0.807 0.844
0:ibo
0.418 0.570 0.673 0.744 0.792 0.832
0:3i2 0.399 0.544 0.652 0.727 0.779 0.830
0:323 0.393 0.523 0.633 0.711 0.767 0.810
0:3a5 0.392 0.507 0.615 0.695 0.757 0.800
. .__
0.675
0.721 0.784 0.829 0.861 0.886 0.907
0.617 0.713 0.777 0.820 0.853 0.880
60.7 Mole Per Cent Isopentane-39.3 Mole Per Cent Propane
.. ..
O:$b7 0.785 0.833 0.869 0.898 0.919 0.936
... ...
0:6i9 0.724 0.791 0.837 0.873 0,899 0.919
...
... ... ...
... ...
O:bi5 0.747 0.805 0.849 0.879 0.903
0:&3 0.697 0.771 0.823 0.859 0.888
... ... ...
89.9 Mole Per Cent Isopentane-10
....
0:kSO 0.764 0.816 0.856 0.886 0.910
... ...
0:5& 0.694 0.769 0.820 0.858 0.887
... ...
... ... ...
...
o:biz
0.717 0.783 0.830 0.864
o:i&
0.660 0.743 0.801 0.842
obtained boiling points differing several degrees from this value. A smoothed correlation of the literature data on the 2-methyl hydrocarbons gives 27.9' C. as the most likely normal boiling point of isopentane (1). The isopentane was deaerated by successive vaporization, condensation with solid carbon dioxide, and evacuation of the residual air. This required only three repetitions to reduce the residual pressure to 0.0001 mm. of mercury when the sample was cooled by liquid nitrogen. The density of propane a t 30' C. was determined in the manner previously described (9). The values obtained were 0.0017979 and 0.0017999 gram per cc. (mean, 0.001799) a t 30' C. and 1 atmosphere. The density of isopentane was measured by vaporizing a sample in an evacuated 500-cc. bulb thermostated a t 30" C.; the excess gas was allowed to escape until the pressure in the bulb equaled atmospheric, and the sample was then condensed in a side arm which was sealed off and weighed. This technique was necessary as the hydrocarbon dissolves in stopcock grease with great rapidity. The values obtained were 0.003021 and 0.003026 gram per cc. (mean, 0.003024) a t 30" C. and 1 atmosphere.
O:.k$O
0.645 0.736 0.796 0.839 0.872
... ...
...
... ... ...
... ... ...
... ...
... ...
...
... ... ...
... ... ...
0:2$7 0.592 0.701 0.770 0.818 0.856
0:3i3 0.542 0.666 0.745 0.798 0.841
0:iio 0.500 0.634 0.721 0.780 0.826
0:%6 0.465 0.605 0.696 0.762 0.812
0:3k7 0.446 0.580 0.673 0.747 0.800
0: 8bo 0.439 0.556 0.656 0.735 0.789
0'. 3 i 4 0.443 0.543 0.643 0.724 0.780
... ...
...
... ... ...
... ... ...
... ...
...
... ... ...
..* .. ....
o.'3i5 0.484 0.625 0.715 0.778
0:3i4 0.448 0.591 0.690 0.757
0 3i6
0:352 0.420 0.543 0.648 0.721
0: 3 i 2 0.421 0.529 0.630 0.707
0:195
Mole Per Cent Propane
... ... ...
o.'iSs
0.597 0.703 0.771 0.821
... ... ...
0:3i2 .0.535 0.663 0.742 0.800
...
...
:
0.427 0.563 0.667 0,738
0.426 0.519 0.614 0.696
Probably the best criterion of purity of a material is that of coincidence of bubble- and dew-point pressures a t temperatures not far below the critical. Kay (6)arbitrarily adopted as a standard a difference of 2 pounds per square inch and considers any sample which has this difference or less to be satisfactory. The propane and isopentane of this research were tested in this manner and the differences in bubble- and dew-point pre-sures were 0.4 a t 50' C. and 1.1 pounds per square inch a t 125' C., respectively.
Experimental Measurements and Evaluation of Errors ' The attainment of equilibrium by the system was found to be rapid in the high-pressure region. However, periods of as long as 30 minutes, during which time the sample was being continuously stirred, were necessary to establish equilibrium a t lower pressures. Figure 1, a plot of 2 us. P for the 89.9 mole per cent isopentane mixture, shows the experimental values which should b? compared with the smoothed curves t o obtain an estimate of the general precision of the measurements (see section on "Preparation and Smoothing of Data").
INDUSTRIAL AND ENGINEERING CHEMISTRY
888
the density of a larger sample of the material was subject to an undeterminable error due to possible inhomogeneities in the material. This error is believed to be under one per cent. The vapor baths used for thermostating the capillary sample tubes were maintained within 0.1" C. of the prescribed temperature in the earlier work on the system. In the later measurements the temperature was maintained within *0.02" C. Several factors were responsible for relatively large errors in the measured liquid volumes. The mercury level could be read with an accuracy of only 0.05 mm. with the cathetometer, which represented a possible experimental error of 1.2 per cent in the measurement of the small volume of the completely condensed sample. The possible error of one per cent in stirrer volumes would cause a similar error in the liquid volumes since the volumes of the stirrers and of the liquid samples were approximately equal. At low temperatures, small quantities of liquid would be trapped between the mercury and the glass capillary as the meniscus rose. This was evidenced by the formation of small bubbles when the temperature was raised.
4c v)
kW!
B v)
0
=!z
3c
W'
e
v) 3 v)
w
a
z 0
2c
5 2
2 v)
iC
0
20
40
60
80
100
COMPOSITION, MOLE % ISOPENTANE
FIGITRE 3. BrnrxE
Vol. 34, No. 7
P O I n T - ~ E WP O I N T
CURVES O F
PRESBWRE V S .
Preparation and Smoothing of Data COhlPOSITIOri
The fundamental messures. volumes. and temperatures obtained in the experimental measurements v-ere expressed as isothermal cornpressibility factors 2 and were plotted against pressure (Figure 1, for example). The intersections of the isochors with the isotherms were then calculated, P and 2 a t constant volume plotted on large-scale graphs against T , and the curves smoothed. The new smoothed values of 2 and P for the isochors were replotted in the 2 t's. P graphs, and the isotherms were shifted to agree. Only a fern minor shifts within a few tenths per cent were required. The iso-
There was considerable uncertainty in the low-pressure measurements (below 7 atmospheres) made a t high temperatures (above 200" (2.). All of the compressibility factors (2= P V / R T ) calculated from measurements in this region appear to be too high and were discarded. The tabulated values arc extrapolated from the isotherms and isochors in the regions of higher pressure and lower temperature. The poor results in this region are thought to be due to the failure of Dalton's law t o hold for mixtures of mercury vaDor and hvdrocarbons. In the calculations the partial pressure of the mercury vapor was assumed to be equal t o its vapor pressure a t the given temperature. The gas sample was apparently com6 pletely saturated with mercury \rapor because the erroneous results were reproducible within the experimental error. I n efforts to define sharply the critical region, short isotherms were measured a t small temperature intervals. Plots of the isothermal compressibility factors vs. pressure failed to show readily discernible breaks a t the dew and bubble points in this region. Consequently the boundaries in the critical regions of the two-phase areas in the 2 us. P plots cannot be defined with such high accuracy as was obtained for other regions. The nitrogen manometers could be read to *0.1 per cent for moderate pressures and within 1.0.2 per cent for the highest pressures. A difference of 0.03" C. in the thermostating of the manometers caused no measurable difference in the pressure readings. The volumes of the capillary sample tubes were calibrated with an accuracy of *0.0002 cc., corresponding to * 2 cc. in the molal volumes of PRESSURE, ATMOSPHERES the gas mixtures. The determinationof thevolumes EQCXLIBRIEM CONSTANTS us. PRESSURE of the small Alnico stirrers by calculation from FIGURE 4. LIQEID-VAPOR
k
INDUSTRIAL AND ENGINEERING CHEMISTRY
luly, 1942
with P were also constructed, smoothed, and rendered selfconsistent. Table IV presents the variation with pressure of the final K values at fixed temperatures. Figure 4 shows the variation of both KI and K2 with pressure on logarithmic scales. For reasons stated above, the experimental saturated liquid volumes were uncertain to the extent of several per cent a t the lower temperatures. The bubble.point compressibility factors for the lower temperatures in the 2 us. P graphs were calculated from the liquid volumes obtained from unpublished correlations of H. D. Evans of the Shell Development Company. The critical volumes were obtained by interpolation of compressibility factor 2 a t the critical pressure and temperature on the bubble-point curve of the 2 us. P plots. Since P, and Tohad already been determined, V c could be calculated. The critical volumes for the several mixtures were smoothed by plotting V , os.. XI. Since the dew-point curve was uncertain in the critical regions of the 2 us. P plots, the critical volumes may be in error by several per cent. The temperatures and pressures of the critical point, maximum temperature point (cricondentherm), and maximum pressure
TABLE 11. PRESSURE-VOLUME RELATIONS OF SATURATED LIQUIDAND VAPOR to
c.
--Bubble PointTT p, atm. oo./L.'mole
C D A ,
z
atm.
0 25 50 75 100 109
4.23 8.43 15.03 25.14 38.50 43.93
10.1 Mole Per Cent Ca 86" 0.016 2.18 91 a 0.031 5.10 0.055 976 10.66 0.094 19.40 107a 0.168 33,42 134 0.243 41.20 174
0 25 50 75 100 110 120
3.74 7.51 13.40 21.93 33.56 40.35 44.75
20.6 89a 930 100" 108a 130 145 180
Mole Per Cent Cs 0.015 1.35 0.028 3.39 0.051 7.29 0.083 13.80 0.143 23.98 0.186 30.30 0.250 38.55
0 25 50 75 100 125 140
2.86 5.75 10.31 16.94 26.12 37.64 44. OS
41.2 955 99' 105' 112' 123" 149 192
Mole Per Cent Cs 0.012 0.87 0.023 2.04 0.041 4.34 0.066 8.59 0.105 15.29 25.74 0.172 0.249 35.65
0 25 50 75 100 125 160 155
2.01 4.10 7.50 12.35 19.32 28.04 38.81 40.90
lola 105" 110' 117a 126s 142 174 195
0 25 50 75 100 125 150 175
0.78 1.73 3.34 6.08 10.10 15.70 23.46 33.45
60.7 Mole Per Cent Cs 0.009 0.73 0.017 1.52 0,031 3.09 0.051 6.31 0.079 11.47 0.122 18.93 0.194 30.84 0.224 33.95
89.9 Mole Per Cent Cs 0.004 0.43 0.008 1.07 113' 0.015 2.23 119" 0.027 4.47 126" 0.044 8.10 134" 0.074 13.14 154 0.113 20.53 167 31.38 0.195 214 llla
Dew PointTI
" I
cc./g. mole
2
9,750 4,330 2,060 1,075 516 330
0.948 0.902 0.825 0.730 0.563 0.433
15,900 6,660 3,170 1,646 889 651 434
0.960 0.922 0.871 0.795 0.696 0.627 0.519
ii;iio
0.'948 0,909 0.852 0.770 0.660 0.535
5,560 2,835 1,540 838 509
I
.
.
.
8,070 4,010 2,170 1,260 649 554
... 0:iio
0.886 0.813 0.728 0.576 0.529
3 w"
t... I
.
.
t K L
... ...
zc
.
5,760 3,180 1,910 1,120 569
0:ibl 0.842 0.768 0.661 0.485
160
140
120
LEGEND
100
a Volumes of saturated liquids calculated from unpublished correlations of H. D. Evans.
I '
thermal values of 2 a t 5-atmosphere intervals are listed in Table I for the various mixtures investigated. The pressurevolume relations of the saturated liquid and vapor are listed in Table 11. Saturation "loop curves" of P us. T for the five mixtures were prepared (Figure 2, Tables I1 and 111). The tangency of the critical locus fixed the critical pressure and temperature for each mixture. The vapor pressure curves for the pure components were taken from Deschner and Brown (a), for propane, and from Young ( I O ) for isopentane. The dew- and bubble-point pressure and the temperatures as plotted in Figure 3 against mole per cent isopentane, xl, enable calculation of the equilibrium constants: K1 = mole- " per cent isopentane in vapor/mole per cent isopentane in liquid, and K z = mole per cent propane in vapor/mole per cent propane in liquid. Plots showing the variation of K
-
180
K
3
....
aa9
01 W W 0:
0
tc
d
tMT tMP
X
I
I
I
I
I
42
I
a v)
0
r
t w
40
38 -
K v) 3 v)
H
-
36
-
34: 34
LEGEND 0
PO
d
PMP
e-23 MOLE % ISOPENTANE
FIGURE5. CRITICALVALUESus. COMPOSITION
TABLE 111. CRITICALVALUES c
Mole yo C6
w&%
Mol. Wt. of Mixture
16.1 20.6 41.2 60.7 89.9 1006
0 13.2 26.6 49.9 69.6 92.7 100
44.09 46.93 49.87 55.65 61.12 69.31 72.14
tc,
C.
97.4 109.3 121.4 142.4 160.2 181.1 187.7
Critical Point, CPo, V, atm. cc./g.Aole 195.2 42.10 197 44.15 201 45.10 44.39 216 236 41.78 284 35.95 307.6 32.90
BO 0.270 0.277 0.280 0.281 0.277 0.274 0.268
--iMax. t$rP
c',
1&:7 121.5 141.8 159.5 181.0
...
Pressure Point, MP-? PMP,
atm.
44;:is 45.11 44.42 41.85 35.98
...
ViUP
cc./g.rn&ea
... 209
223 209 216 262
...
--Max.
ZMP
:
0 i94 0.310 0.273 0.254 0.253
...
tMT, 0
C.
Temp. Point, M T - 7 PMT,
VMT,
atm. cc /g.molea
ZMT
..I
iii):6 123.6 145.1 161.0 181.5
...
43:6 43.7 42.9 40.2 35.6
..
250 294 317 348 356
...
0: i 4 2 0.394 0.396 0.393 0.340
...
2 were read from appro riate ourves and V values calculated from them. No.attempt at smoothing was made, and high accuracy canSimilar measurements ma& by Kay (6jon the n-butane-n-he tane system show simllar variations wlth mole fraction.
a These values of
not he claimed. b T h e values for the pure components are taken from Murdooh and Souders
b).
890
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 34, No. 7
TABLEIV. PHASE EQUILIBRIUM DATA" P 0.33 0.5 0.75 1.o 1.2 1.5 2.0 3.0 4.0 4.75 4.0 5.0 7.0 8.5 10.0 13.0 15.0 20.0 25.0 28.3
100.0 96.5 91.2 84.2 78.8 72.6 61.0 37.9 15.0 0.0
1.56
0.0
0.0
-75' C.100.0 80.3 53.4 41.9 33.5 22.7 17.8 9.3 3.38 0.0
100.0 96.5 86.9 77.4 73.6 68.0 64.1 60.2 58.3 56.2 54.0 51.6 49.0
-150' C. 100.0 91.9 74.5 62.4 58.5 53.3 50.6 48.3 47.5 47.0 46.9 47.5 49.0
100.0 95.4 85.3 78.2 71.0 57.7 49.1 28.9 10.6
r
18.10 20.0 25.0 30.0 32.0 35.0 37.0 39.0 40.0 41.0 42.0 43.0 43.5
i00:o 64.9 50.2 29.7 23.6 17.9 11.6 5.04
1.0 0.673 0.550 0.352 0.299 0.247 0.190 0.133 0.103
...
...
... 41441 3.610 2.995 2.265 1.529 1.158 1.0
__ 1.0 0.842 0.626 0.536 0.472 0.394 0.363 0.322 0.319
1.0 0.952 0.857 0.806 0.795 0.785 0.789 0.802 0.815 0.836 0.869 0.920 1.0
4:i52 3.170 2.711 2.293 1.827 1.615 1,276 1.081 1.0
2:3i4 1.947 1.664 1.572 1.458 1.376 1.300 1.257 1.210 1.153 1.086 1.0
0.88 1.5 2.0 2.5 3.0 4.0 5.0 7.0 9.32
--
--
0.0
c.
7.04 8.5 10.0 13.0 15.0 20.0 25.0 30.0 32.0 35.0 37.0 39.0 40.0 41.0 42.0 42.55
-1000 100.0 100.0 95.1 84.7 90.3 71.7 50.4 80.5 42.3 74.3 28.7 58.6 44.2 20.1 13.7 30.6 11.6 26.5 18.0 8.6 6.7 13.5 4.9 9.05 4.0 6.9 4.8 3.05 2.15 2.9 1.7 1.7
21.50 25.0 30.0 32.0 35.0 37.0 39.0 40.0 41.0 41.8
100.0 93.8 84.9 81.2 75.8 72.1 68.0 65.8 63. .5 60.4
__"
Acknowledgment The authors find it a pleasant duty to express to M. Souders, Jr., P. G. Murdoch, and H. D. Evans of the Engineering Department of Shell Development Company, their appreciation for constructive criticism during t,he progress of this work, especially during the calculations and correlations. These investigators are now engaged in the study of generalized correlations of hydrocarbon behavior. To Noel R. Graves goes the authors' thanks for assistance in the first stages of the experiments. L. H. Bayley aided in the preparation of the isopentane, and F. F. From in that of the propane. Nomenclature P = pressure, atmospheres v = volume, cc./gram mole R = gas constant = 82.06 cc. atm./" K. t = Eemperature, C. T = temperature, K. = t o 273.16' C. z = compressibility factor = P V / R T 21 = mole per cent isopentane in liquid Q = mole per cent propane in liquid Yl = mole per cent isopentane in vapor Y2 = mole per cent propane in vapor O
+
.E
100 59.6 41.9 31.4 24.6 15.7 10.3 4.1
100.0 92.6 86.3 80.2 73.9 61.8 49.9 26.6 0.0
point plotted against composition may be seen in Figures 4 and 5. These diagrams are similar to those given by Kay (6) for the n-butane-n-heptane system.
O
K1
Yl
XI
100.0' 87.7 74.3 70.1 64.7 61.8 59.7 59.1 58.9 60.4
1.0 0.644 0.486 0.392 0.333 0.254 0.207 0.154
...
1.0 0.891 0.794 0.632 0.569 0.490 0.454 0.448 0.455 0.478 0.498 0.541 0.581 0.635 0.741 1.0 1.o 0.935 0.876 0.863 0.853 0.858 0.878 0.897 0.927 1.0
Ka
... 4:i46 3.470 2.891 2.208 1.791 1.306 1.0
--... ... ...
... 1:ji.Z
1.433 1.244 1.877 1.115 1.078 1.046 1.03 1.02 1.01 1.0 1:9?6 1.702 1.590 1.462 1.365 1.259 1.199 1.128 1.0
P '--2.0 3.0 4.0 5.0 7.0 10.0 13.0 15.0 17.0
XI
100.0 92.2 85.0 77.9 64.2 43.8 23.9 10.3
,o.o
7-
l/i
-500
c.-
100.0 63.2 45.4 34.5 21.8 11.4 5.19 2.13 0.0
Kt 1.0 0.686 0.534 0.443 0.339 0.260 0.217 0.207
...
-125O C.-
... K2
3:610
2.968 2.185 1.577 1.243 1.091 1.0
...
11.52 15.0 20.0 25.0 30.0 32.0 35.0 37.0 39.0 40.0 41.0 42.0 43.0 44.0 45.2
100.0 91.9 79.5 67.7 56.3 52.1 46.1 42.3 38.7 36.9 35.1 33.1 30.9 28.5 24.0
25.18 30.0 32.0 35.0 37.0 39.0 39.6
100.0 92.3 88.9 83.5 79.6 75.3 73.5
170' C. 100.0 86.8 82.3 76.5 73.9 72.5 73.5
1.0 0.941 0.926 0.917 0.928 0.963 1.0
1.595 1.421 1.282 1.113 1.0
z.33 32.0 35.0 36.5
100.0 96.2 91.0 87.8
1800 c 100.0' 94.3 88.5 87.8
1.0 0.980 0.973 1.0
1:4i)4 1.278 1.0
-
100.0
78.9 56.9 43.7 34.8 32.1 28.5 26.5 24.7 23.8 23.1 22.4 21.9 21.0 24.0
1.0 0.859 0.716 0.646 0.618 0 . m 0.618 0.626 0.637 0.645 0.658 0.679 0.709 0.767 1.0
2: ibo 1.740 1.492 1.419 1.327 1.275 1.229 1.208 1.185 1.158 1.130 1.093 1.0
1:fi4
P., V,, T. = critical Dressure. volume. and temoerature.
r espectiively ' maximum temperature for existence of liquid phase (cricondentherm) pressure at point of maximum temperature volume at point of maximum temperature maximum pressure for coexistence of liquid and vapor phases temperature at point of maximum pressure volume at point of maximum pressure
Literature Cited (1) Carleton, L. T., private communication. (2) Deschner, W.W., and Brown, G. G., IND. ENG.CHXIM., 32,836 (1940). (3) Hicks-Bruun, M.,and Bruun, J., J . Am. Chem. Soc., 58, 810 (1936). (4) Kay, W.B., IND. ENO.CHBM.,24,291 (1932). (5) Ibid., 30,460 (1938). (6) Ibid., 33,590 (1941). (7) Murdoch, P.G., and Souders, M., Jr., private communication. (8) Timmermans, J., and Martin, F., J . chim. phys., 23, 733 (1926). (9) Vaughan, TV. E.,and Graves, N. R., IND.E m . CHBM.,32, 1252 (1940). (IO) Young, Sidney, Sci. Proc. Roy. Dublin Soc., 12, 418 (1910). (11) Young, Sidney, "Stoichiometry", p. 132, London, Longmans, Green and Co., 1908. (12) Young, Sidney, and Thomas, G. L., J . Chem. SOC.,71,440 (1897), PRESENTED before the Division of Physical and Inorganic Chemistry a t the 103rd Meeting of the AMERICAN CHBMICAL SOCIETY, Memphis, Tenn.
