October 1955
INDUSTRIAL AND ENGINEERING CHEMISTRY
Figures 1 through 5 plot the experimental temperature-composition data for each of the systems. I n Figures 6 through 10, activity coefficients are plotted against liquid composition. CONCLUSIONS
All five paraffin-aromatic systems studied in this myork show considerable deviations from ideality. There is no evidence of azeotrope formation, although the temperature-composition diagrams for both hexane-benzene and benzene-heptane pinch together closely a t the low boiling ends of the diagrams. I REFERENCES (1)
Hipkin, IT. G., and Myers, H. S., IND.ENG.CHEM.,46, 2524 (1954).
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(2) Dodge, B. F., Chemical Engineering, Thermodynamics, 1st ed., p. 562, McGraw-Hill, New York (1944). (3) Myers, H. S., American Documentation Institute, Document No. 4595 (1955). (4) Sieg, L., &ern.-1ng.-Tech., 22, 322 (1950). ( 5 ) Tongberg, C. O., and Johnston, F., IND. ENG.CHEM..25, 733 (1933). RECEIVED for review December 13, 1954. ACCEPTED April 18, 1955. A more detailed form of this paper (or extended version, or material supplementary to this article) has been deposited as Document No. 4595 with the AD1 Auxiliary Publications Project, Photoduplication Service, Library of Congress, Washington 25, D. C. A copy may be secured by citing the document number and b y remitting $2.50 for photoprints or $1.75 for 35mm. microfilm. Advance payment is required. Make checks o r money orders payable t o Chief, Photoduplication Service, Library of Congress.
Phase Equilibria in Hydrocarbon N
Systems VOLUMETRIC BEHAVIOR OF n-HEPTANE W. B. NICHOLS, H. H. REAMER, AND B. H. SAGE California Institute of Technology, Pasadena, Calif.
I
^\FORMATION concerning the influence of pressure and temperature upon the specific volume of the lighter paraffin hydrocarbons is of interest in a number of industrial operation*. Rossini (7') summarized the physical properties of nheptane a t atmospheric pressure. Beattie ( 1 , IO) and others studied the volumetric behavior of n-heptane a t elevated pressures. Eduljee, Newitt, and Weale (4)investigated the volumetric behavior of its liquid phase at temperatures below 140" F . and a t pressures u p to approximately 75,000 pounds per square
Table I.
inch. Gilliland and Parekh ( 5 )determined the effect of pressure upon the enthalpy of this hydrocarbon for pressures below 1000 pounds per square inch. Stuart, Yu, and Coull ( I S ) calculated the thermodynamic properties from existing data for pressures up t o 300 pounds per square inch. The freezing point of nheptane was determined by Streiff ( 1 2 ) and others and the boiling point was established by Smith and Matheson (9). All these data established the volumetric behavior of this compound with fair accuracy, despite disagreement of the
Experimental Volumetric Measurements for
n-Heptane
(Sample weight 0.248666 lb.) Pressure, Lb./Sq. Inch Abs.
Specific Volume, Cu. Ft./Lb.
9979.7 9536.9 8955.4 8083.0 6965.7 5927.6 4968.6 3942.3 2911.7 1911.5 913.8 36.5 25.2
40" F. 0.021575 0.021636 0.021695 0.021786 0.021915 0.022055 0.022193 0.022330 0.022480 0.022744 0.022826 0.022977 0.022981
9874.3 9485.7 9037.2 8015.0 7065.0 5915.2 5006.9 3956.2 3033.8 2014.7 947.8 34.4 24.1
160' F. 0.022861 0,022922 0.022996 0.023152 0.023308 0.023498 0.023692 0.023903 0.024137 0.024410 0,024732 0.025023 0.025031
Pressure, Lb./Sq. Inch Abs.
Specific Volume, Cu. Ft./Lb.
9494.7 9073.2 8059.2 7077.5 6081.1 5033.9 3932.6 2896.7 1964.5 868.5 103.2 36.7 21.9
100' F. 0,022280 0.022324 0 022459 0 . 022598 0 022741 0.022904 0,023093 0,023292 0.023475 0.023724 0 023911 0.023939 0,023941
10011.5 9471.2 9002.0 8006.0 7070.0 6057.7 5001.5 4007.1 3018.7 2012.3 978.9 34.1 25.9 17.9 17.6
220' F. 0.023486 0.023553 0.023663 0.023839 0.024042 0.024265 0,024518 0,024800 0.025107 0,025436 0.026852 0.026378 0.026388 0.029025 0.062026
Pressure, Lb./Sq. Inch Abs. 9604.0 9032.2 7163.8 5348.3 3081.5 931.9 122.9 61.2 39.9 39.3
9768.3 9549.2 9105.6 8079.7 7171.9 6057.0 4982.8 4006.4 2987.9 1968.1 934.9 446.2 241.7 158.3 155.3 154.7
Specific Volume Cu. F t . / i b .
280' F. 0.024162 0.024266 0,024725 0.025246 0.025932 0.027127 0.027839 0.027941 0,034996 0.059339
.
0.025501 0.025549 0.026678 0.0259~6 0.026300 0.026741 0.027229 0,027805 0,028501 0.029420 0.030856 0.031898 0.032540 0.037729 0.054006 0.075550
Pressure Lb./Sq. Idch Abs. 10028,l 9586.7 9160.2 8046,l 7072.6 6011.5 5024.3 4023.5 2998.9 1962.7 884.5 340.2 132.0 86.7 84.7 84.3
340° F. 0.024764 0.024861 0.024977 0.025253 0.025588 0.025877 0.026282 0.026690 0.027216 0.027858 0.028834 0.029494 0.029855 0.037815 0.055259 0.074289
9879.2 9527.0 9099.0 8089.8 7044.6 5935.3 4984.5 3921.4 2947.6 1919.5 1404.2 886.6 493 5 390.6 263.7 262.4 260.9 t
Specific Volume, Cu. Ft./Lb.
460° F. 0.026153 0.026296 0.026394 0,026761 0.027194 0.027783 0.028286 0.029032 0.029921 0.031284 0.033731 0.032270 0.035590 0.0363 64 0.050854 0,064656 n ,088502
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Z
0
Vol. 47, No. 10
y
AUTHORS
YN
NEWITT
0.003
l-
->a
W
0
0.00 2
I!
a
tW
5
0.00I
A
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4000 PRESSURE
2000 I
2000
Figure 1.
1
4000 PRESSURE
I 6003 LB. PER S W N .
I 8000
I Figure 3.
6000
8000
LB. PER SQ.IN.
Deviation of Newitt's measurements from present investigation
Molal volume of n-heptane in liquid phase
measurements of Kewitt with those of Beattie ( I O ) . As it was desired to establish partial volumetric behavior for binary mixtures involving n-heptane, the influence of pressure and temperature upon the molal volume of n-heptane was studied a t pressures u p to 10,000 pounds per square inch in the temperature interval between 40' and 460' F. METHODS AND APPARATUS
Methods and equipment employed were the same as those used in the study of n-nonane ( 3 ) and n-hexane (11). The procedure involved confinement of a sample of n-heptane of known weight over mercury in a stainless steel chamber and measurement of the volume of the system occupied by the hydrocarbon as a function of state. A detailed description of the equipment is available (8). Temperature of the sample was determined from the indications of a platinum resistance thermometer of the strain-free type (6) which had been compared with the indications of a reference instrument calibrated by the National Bureau of Standards. Experience indicated that the temperature of t h e Figure 2. Deviation of Beattie's measurements from sample was related t o the international platinum scale with a present investigation probable error of 0.02" F. Pressures were measured with a balance involving a pistonTable 11. Molal Volumes of n-Heptane in Liquid Phase c y l i n d e r combination which was calibrated a g a i n s t t h e Pressure, Lb./Sq. Inch v a p o r p r e s s u r e of c a r b o n 400' F. 460" F. 100" F. 160° F. 220° F. 280' F. 340' F. Abs . 40' F. dioxide a t the ice point (2). (257.8) (17.48) (40.96) (83.20) (151.4) (1.58) (6.11) (0.325)= 3.32 3.87 2.397 2.508 2.644 2.804 3.01 B.p. 2.302 T h e p r e s s u r e s were known ... 3.28 200 within 0.1% or 0.2 pound per 3 . 6 3 3.21 400 3.50 3.16 square inch, whichever was t h e 600 3 . 4 1 3.11 800 larger uncertainty. Agitation 3.34 3.08 1,000 3.27 3.04 1,250 of the sample was provided in 3.21 3.00 1,500 3.16 2.973 order t o hasten physical 1,750 3.12 2.945 2,000 equilibrium. The volume of t h e 3.08 2.919 2,250 3.05 2.895 2,500 system occupied by n-heptane 3.02 2.874 2,750 2.994 was known with a probable 2,856 3,000 2.945 2.819 3,500 error of 0.25% at pressures 2.903 2,785 4,000 2.756 2.866 4,500 5000 pounds per square below 2.831 2.730 5,000 2,777 2.680 0 000 inch and 0.4% a t higher pres2.726 2.689 7 000 sures. The weight of n-heptane 2.684 2.604 8,000 2.647 2.574 9,000 was determined by weighing 2.545 2.612 10,000 bomb techniques (8) and by Values in parentheses represent bubble point pressures expressed in pounds per square inch. c o m p a r i s o n of v o l u m e t r i c b Volume expressed in cubic feet per pound mole. * measurements a t atmospheric
:
October 1955
INDUSTRIAL AND ENGINEERING CHEMISTRY
pressure ( 7 ) with critically chosen values of specific weight, with a probable error of less than 0.05%. MATERIALS
The n-heptane was purchased as research grade from the Phillips Petroleum Co. and was reported to contain 0.0006 mole fraction of impurities. It was fractionated once a t reduced pressure in a column containing 16 glass plates a t a reflux ratio greater than 20. The first and last 10% of the overhead was discarded. After passage of the liquid through activated alumina and deaeration by prolonged refluxing a t reduced pressure, it was dried over metallic sodium. The specific weight of the sample of n-heptane a t 77’ F. was 42.4232 pounds per cubic foot, which compared with 42.4195 pounds per cubic foot reported by Rossini for an air-saturated sample a t the same temperature. The index of refraction for the deaerated sample relative to the D-lines of sodium was 1.3853 as compared to a value of 1.3851 reported by Rossini for an air-saturated sample. A comparison of these data indicates that the sample employed for these measurements probably contained less than 0.0005 mole fraction of material other than n-heptane. I t is believed that the impurities are primarily isomeric hydrocarbons. EXPERIMENTAL RESULTS
The measurements of the volumetric behavior of n-heptane are given in Table I. No results were reported for the two-phase region, since the vapor pressure was already well established ( 1 , 7 , 10). The experimental results are depicted in Figure 1. The standard deviation of the experimental points from the smoothed curve was 0.0016 cubic foot per pound-mole Smoothed values of the molal volume of n-heptane for each of the temperatures investigated are recorded in Table 11. The bubble point pressures included in this table were taken from the critically chosen values of Rossini ( 7 ) a t the lowe. temperatures and the measurements of Beattie ( 1 , IO) a t the higher temperatu-es. The deviation of Beattie’s volumetric measurements from the present investigation is shown in Figure 2. The standard deviation of 45 experimental points obtained by Beattie (IO)from the smoothed data of Table I1 was 0.0062 cubic foot per pound-mole.
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This corresponded t o 0.23% deviation based upon the average molal volume. This variation is within the probable errors of the two sets of measurements. Figure 3 shows the deviation of Newitt’s measurements from the present data. I n this instance the standard deviation from the information presented in Table I1 was 0.0043 cubic foot per mole, which corresponds to 0.19yo deviation based upon the average molal volume of n-heptane ACKNOWLEDGMENT
This paper is a contribution from American Petioleum Institute Project 37 at the California Institute of Technology. Virginia Berry aided in the reduction of the data and Elizabeth McLaughlin with the preparation of the manuscript, which was reviewed by W.N. Lacey. LITERATURE CITED (1) Reattie, J. A, and Kay, W. C., J . A m . Chem. Soc., 59, 1586 (1937). (2) Bridneman. 0. C.. Ibid.. 49. 1174 (1927;. (3j Carmichael, L. T . , Sage, B: H., and Lacey, W. S . , IND.EXG. CHEM., 45,2697 (1953). (4) Eduljee, H. E., Newitt, D. M., and %’eale, K. E., J . Chem. Soe., 1951, p. 3086. (5) Gilliland, E. R., and Parekh, M. D., IXD. ENG.CHEM.,34, 360 (1942). (6) Myers, C. H., Bur. Standards J . Research, 9 , 807 (1932). (7) Rossini, F. D., Pitzer, K. S., Arnett, R. L., Braun, R. M., and Pinientel, G. C., “Selected Values of Physical and Thermodynamic Properties of Hydrocarbons and Related Compounds,” Carnegie Press, Pittsburgh, 1953. (8) Sage, B. H., and Lacey, W. N., Trans. A m . Inst. Mining Met.
Engrs., 136, 136 (1940).
(9) Smith, E. R., and Matheson, J., J . Research A‘atl. Bur. Standards. 20.641 (1938). (IO) Smith, L. B., Beattie‘, J . A . , and Kay, W. C., J . Am. Chem. Soc., 59,1587 (1937). (11) Stewart, D. E., Sage, B. H., and Lacey, W. N., IXD. ENG.CHEM., 46,2529 (1954). (12) Streiff, A. J., Murphy, E. T., Sedlak, V. A., Willinghani, C. B., and Rossini, F. D., J . Research Natl. Bur. Standards, 37, 331 (1946). (13) Stuart, E. B., Yu, K. T., and Coull, J., Chem. Eng. Progr., 46, 311 (1950). RECEIVED for review January 27, 1956.
ACCEPTED March 9, 1955.
Butadiene-Aery lic Acid Copolymers C. S. MARVEL, RICHARD POTTS, JAMES ECONOiMY, AND G. P. SCOTT Noyes Chemical Laboratory, University of Illinois, Urbana, I l l .
W. I
