A Pennsylvania straight-run gasoline, a West Virginia natural gasoline, and a Michigan straight-run gasoline were fractionated in an efficient fractionating column. The gasolines were separated into fractions of widely different boiling spreads, refTactive indices, and octane numbers. Differences were noted in the composition of the Pennsylvania and Michigan gasolines ; the complexity of the Pennsylvania gasoline was marked in comparison with the Michigan gasoline. The separation of gasoline into fractions of narrow boiling range should not only furnish fractions having high antiknock qualities but should also furnish fractions suitable for Diesel fuels, for solvents, especially as diluents for present organic solvents, and for starting materials in the manufacture of organic chemicals.
Composition of Straight-Run Pennsylvania Gasoline IV. Fractionation of Straight-Run Gasoline'
C. 0. TONGBERG, D. QUIGGLE, AND M.R. FENSKE Pennsylvania State College, State College, Pa.
P
REVIOUS fractionations of Pennsylvania gasoline (3) have shown the general constitution of a Pennsylvania straight-run gasoline and a means of changing its physical properties as well as its antiknock qualities. Fractionations of other gasolines have now been made, and since they were all run in a corresponding manner a direct comparison may be obtained.
The fractionation was made in an aluminum column packed for 27 feet with No. 19 single-link aluminum jack chain. The still was of the thermosiphon type and had a capacity of 50 gallons. Both the still and the column were heated electrically. Temperatures were measured by chromel-alumel thermocouples. The column had a total condenser, and the rate of distillation was measured by obtaining the number of B. t. u. picked up by the cooling water. When tested under total reflux with a mixture of n-heptane and methylcyclohexane, the column had the equivalent of approximately thirty-five theoretical plates. Forty gallons of the gasoline were put into the still and fractionated at a reflux ratio of approximately 26 to 1. The fractionation was completed in 6 days. The amount of gas evolved was not measured, but tests on smaller samples indicated that 10 per cent by volume of the charge had been distilled when the reflux temperature was 122"F.
Pennsylvania Straight-Run Gasoline This galsoline,from the Bradford field, mas obtained from the Pennsylvania Refining Company and had the following properties: A . S.T. M . Engler Diatn. Initial b. p.
60
70
F. 102 179 207
229 242 268 284 303
A. S. T. &'I. Engler Distn. O F 323 343 360 370
A. P. I. gravity Octane No.
The results of the fractionation are given in Figure 1. The familiar rise and fall in refractive index with increasing boiling point is evident. Even more abrupt changes are noted in the octane number curve. Table I shows the concentration of the gasoline into fractions of narrow boiling range and also gives the octane numbers of these fractions. These fractions were made by combining a number of smaller fractions, all within the boiling range noted. Table I1 gives the maximum and minimum octane numbers observed. Blends of the fractions in Table I were made in order to determine the best yield of antiknock gasoline that could be obtained as a result of this fractionation. These results are given in Table 111. The octane number of the original gasoline minus the material boiling below 122" F . 4 . e., the gaso40. The gaseous products line actually fractionated-was in the original gasoline-i. e., some propane, mostly butane and pentane-therefore give an increase of 8 octane numbers.
61.9 48
The octane number and the 10 per cent of the A. S. T. M. Engler distillation are lower than for a representative Bradford straight-run gasoline. All octane numbers were obtained with a Series 30A Ethyl knock-testing engine operating a t 600 r. p. m. and 212"F. jacket temperature, except as noted in Figure 3 . 2 1 Parts I, 11, and 111 appeared on pages 408, 542, and 814, respectively, of Volume 24. 1932. * Because of the introduction of the C. F. R. motor method during the course of this study, the Ethyl engine was converted t o series B and operated according to procedure 346 of the Ethyl Gasoline Corporation. This procedure specifies a jacket temperature of 345O F. and a motor speed of 900 r. p. m. These procedures give good agreement for high octane numbers and fair agreement f o r low octane numbers. Ootane numbers of the more recent fractionations were obtained by procedure 345.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
202
TABLEI. FRACTIONS OF NARROW-BOILING RANQEFROM PENNSYLVANIA STRAIQHT-RUN GASOLINE Vol. Per
Boiling Boilin Range,* Spreacf, Octane F. F. No. 97-198 101 61 199-210 11 47 211-244 33 58 5 245-250 46 251-268 17 39 269-284 15 58 285-300 15 20 6.8 301-318 17 20 5.9 319-334 14 41 7.9 335-352 17 19 21 4.5 353-374 22 6 76 Still residue 16 points are given at a pressure of 29 inahee of mercury. Cent of Charge 15.8 8.0 8.9 4.0 8.7 5.7 6.5
Fraction 1 2 3 4 5 6 7 8
a
9 10 11 12 All boiling
AND MINIMUM OCTANE NUMBERS TABLE11. MAXIMUM FROM PENNSYLVANIA STRAIGHT-RUN GASOLINE
Identifying Constituents Isomeric hexanes n-Hexane Benzene n-Heptane Toluene
Boiling Point,
F.
Identifying Constituents n-Octane Xylene n-Nonane Trimethylbenzenea n-Decane
Octane No.
97-126 153 178 206 223
74
55 72
39
67
Boiling Point,
OF.
Octane
No.
258 277 297
29
324 343
54
67 15
A natural gasoline from the Smithfield, W. Va., field obtained from the South Penn Oil Company was fractionated in a manner similar to the above straight-run Pennsylvania gasoline. This natural gasoline had the following properties: A. 8.T.M.
A. 8.T.M.
Engler Distn. Initial b. p.
O
F. 95
Engler Distn.
O
F.
188 206
A. P. I. gravity Octane No.
74.0 58 7
40 50
fractionated at a reflux ratio of approximately 29 to 1. The fractionation was completed in 5 days. The gas evolved corresponded to 5.0 per cent by volume of the charge. The results of the fractionation are given in 'Figure 2. Practically pure isopentane and n-pentane were obtained. A considerable amount of a fraction consisting mainly of n-hexane was obtained. The higher concentration of the individual hydrocarbons in this gasoline makes it a good starting material in any attempt to isolate low boiling hydrocarbons. Blends of the various fractions were made, and octane numbers of these blends obtained. These results are given in Table IV. The octane number of the fraction, b. p. 178" F., in which the benzene is concentrated was 85, obtained according to procedure 345. Since the concentration of benzene in this fraction is approximately only 30 volume per cent, the high octane number must be due to the branched heptanes boiling in this vicinity. The high antiknock value OF such hydrocarbons is well known (6). TABLE111. OCTANENUMBER OF BLENDS OF FRACTIONS FROM PENNSYLVANIA STRAIQHT-RUN GASOLINE
16
Natural Gasoline
173
VOL. 28, NO. 2
VOl. Per Cent of Charges 99.4
Fractione (Table I) 1-12
Blend5 A B
80.6
1-9
Si.3
1-6
C
D
Chpge in Octane 00No. tane from No. Original 47 1 '
End
Frit, F.
...
834 284 ~~~
-2 +
so -_
i n
57 60
54.2 334 1-3, 6, 9 4-12 1-4 6 52.6 284 62 +14 F 1 d4,6 44.6 284 64 16 1' 3' 6 40.3 284 0 66 4-18 H 3, 5. 7,'8,'10, 11, 1 2 48.7 28 -20 0 All blends except H contain the gas (1. e some propane mostly butane and pentane) evolved at the start of the frsbtionation. T i i s accounts for octane numbers here being sometimes higher than the fractions listed in Table I from which these blends were made.
E
+
...
TABLEIV. OCTANENUMBERS OF BLSNDSOF FRACTION^ FROM WESTVIRGINIA NATURAL GASOLINE
The fractionation was made in the previously described aluminum column. Forty gallons were put into the still and All fractions
A B
All fraotions except noctane and residue Blend of high-octane number
C
96
-2
56
70.5 30.0
82-236
jS:-:tP)
210-235 6.1 D Toluene fraction 210-235 6.0 146-155 E n-Hexane fraction 9.7 244-273 F n-Octane fraction These blends do not include the gas evolved at the tionation.
.
64
+6
72
+I4
+-
7 50 8 42 -16 start of the frao65
Michigan Straight-Run Gasoline A gasoline from the Mt. Pleasant field in Michigan obtained from the Pure Oil Company was fractionated in a manner similar to that described. This gasoline had the following properties: A. S.T.M. Engler Dish Initial b. p.
50
60
o
F. 110
O
178 210 242 270
330
A:S. T.M. Engler Distn. 90%
End point Octane No. A. P. I. gravity
F. 356 378 401 448
7- 10 58.8
The previously described aluminum column was used which, owing to changes in design, now had the equivalent of approximately fifty-five perfect plates when tested under total reflux with a mixture of n-heptane and methylcyclohexane. FIGURE1. FRACTIONATION OF A PENNSYLVANIA STRAIQHT-RUN Forty-five gallons were charged into the still and fractionated a t an average reflux ratio of 18 to 1. The fractionation GASOLINE
FEBRUARY, 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
203
was completed in 5 days. The results of the fractionation are given in Figure 3. The efficient fractionation of such a relatively noncomplex gasoline gave remarkable changes in boiling point and refractive index. The n-paraffins gave fractions of very narrow boiling range (0.9" to 5.2' F.) while the intermediate fractions, although constituting no greater a percentage of the charge than any one n-paraffin, had boiling ranges of 38" to 59" F. This shows that specific portions of the gasoline could be obtained easily. Table V shows the concentration of the gasoline into fractions of narrow boiling range. OF NARROW BOILING RANGE TABLEv. FRACTIONS FROM MICHIGAN GASOLINE
Identifying Constituents n-Pentane n-Hexane Beneene %-Heptane Toluene n-Octane Xylene n-Nonane Trimethylbenaenes n-Derane
Per Cent of Charge 1.06 5.00 5.64 7.53 6.25 6.25 5.63 6.25 6.57 5.32
Boiling Range, a F. 94.1- 95.0 152.2-154.8 164.8-204.8 204.8-210.0 210.0-253.2 253.2-266.8 256.8-298.8 298.8-302.9 302.9-340.8 340.8-344.3
Boiling Spread, O
F.
0.9 2.6 50.0 5.2 43.2 3.6 42.0 4.1 37.9 3.5
--l
TABLEVI. COMPARISON OF PENNSYLVANIA AND MICHIGANGASOLINE PP?
Identifying Constituents Iaomeric hexanes n-Hexane Isomeric heptane8 n-Heptane Iaomeric octanes --Octane
Boiling Range, F. 143.2-149.9 149.9-160.0 190.6-199.2 199.2-213.4 234.0-260.8 250.8-259.2
Boiling Spread,
F. 6.7 10.1 8.6 14.2 16.8 8.4
&t
of
Pa. Charge 3.36 2.7 4.07 9.41 7.50 5.46
-.
Par -
l l l l l i i l i l l l l l l l l l
5
l
o
l
5
!
l
O
~
I I I I I I
3
0
J
Volwze Pat& of Charge D&lilkd OW
~
B
~
FIGURE 3. FRACTIONATION OF A MICHIGAN STRAIGHT-RUN GASOLINE
Cent
of Mioh.
The numbers in circles are octane numbera obtained according to procedure 345.
Charge 0.82 6.78 1.23 10.05 1.88 7.72
The fractions of the gasoline in which the aromatics were concentrated were straw colored or dark brown. On simple redistillation of these fractions the distillate was colorless. This coloration was probably caused by the action of sulfur compounds on certain copper parts. It appears, then, that in this instance the sulfur compounds were concentrated in the aromatic fractions. Octane numbers of various fractions were obtained according to procedure 345. The results are given in Figure 3. The sharpness of separation of the hydrocarbons in the gasoline is well illustrated by the rapid change in octane number, 18 to 61, from 207" to 211' F. boivng point.
The Michigan straight-run gasoline has a greater amount of n-paraffins and aromatics than Pennsylvania-straight run gasoline but a much smaller amount of branched paraffins. This is shown in Table VI. The higher fractions were not compared because of the increase in complexity. Although neither the original Michigan gasoline nor any of the fractions gave a doctor test, the odor and the attack on certain copper parts of the column indicated sulfur compounds to be present.
Discussion of Results
I n the tables the columns marked "identifying constituents" mean that these constitutents are those most readily identified in these particular fractions. It does not mean that these are the only constituents present nor does it necessarily mean that they are even the principal constituents. Rather this is used in a more general sense to permit the F nomenclature fractions to be readily identified and to indicate the compounds most readily isolated. In the figure the Engler spread is the difference between the initial and 50 per cent boiling point when using the modified Cottrell boiling-point apparatus (7) on fractions which were 0.3 to 0.6 per cent of the charge. All boiling points reported 2 here are separate measurements on these fractions, after the distillation was completed, using this same boiling point apparatus. The boiling points listed are the temperatures when 50 per cent has been distilled. Proper blending of the fractions, as well as proper cutting of the fractions from the gasoline, is important in obtaining materials of high octane number. The effect on octane number bblurne Brcent gf C k g e Dsftlled O w of certain hydrocarbon types when present along with others FIGURE2. FRACTIONATION OF A WEST VIRGINIA NATURAL has already been pointed out in the work of Garner (4) and GASOLINE Boyd ( I ) and their co-workers in investigations of blending
!i
$
g
~
~
204
INDUSTRIAL AND ENGINEERING CHEMISTRY
octane numbers and lead susceptibility. Fuels of higher octane number might be obtained by proceeding in at least three different ways: (I) segregating the desired hydrocarbons of high antiknock value from all others in the gasoline, (2) segregating and combining not only the high octane number types but also those of high octane blending value and combining these with other hydrocarbon type$ of only fair octane number to make available a greater volume of fuel, and (3) segregating and combining the high octane number types as well as those very reponsive to tetraethyllead. I n this way fuels of very high octane number could be produced, for the recent work of Boyd and co-workers (1) has shown certain hydrocarbons-for example, the branched paraffins and the substituted benzenes-to permit marked increases in critical compression ratio upon the addition of 1 cc. of tetraethyllead, in comparison with other hydrocarbon types. The patent of Henderson and Ferris (5) relates to a process for obtaining gasoline of high antidetonating quality by fractional distillation. This patent relates to the separation of the paraffinic hydrocarbons from the aromatic and naphthene types, the paraffinic types being considered undesirable as high-antiknock fuel. It is now known that certain paraffinic types are highly desirable, in many instances more so than the aromatic hydrocarbons, such as benzene, which are available commercially for blending with motor fuels. The fractions or hydrocarbons suitable for the high-antidetonating fuel according to this patent are those of high specific gravity and low aniline point. It now appears in view of the recent work on the octane numbers of various hydrocarbons and their physical constants ( I , @ that the only sure way to recognize the desirable hydrocarbons resulting from efficient fractional distillation of gasoline is either to know definitely their chemical formula, or else have available reliable and rather extensive tests of their antiknock qualities a t high engine temperatures, as well as their octane blending value and susceptibility to tetraethyllead. The apparent parallelism between density and refractive index curves and knock rating that was thought to exist earlier, no longer holds on more efficient fractionation or for gasolines from different sources. This is apparent in the case of the Michigan straight-run gasoline shown in Figure 3 where, in the low- as well as in the
VOL. 28, NO. 2
high-boiling fractions, high octane number and high refractive index do not necessarily coincide. There may be several reasons for this: (1) because of efficient fractionation, the isolation of the constituents in the gasoline has been sharper and ( 2 ) the boiling points of the hydrocarbons themselves may have been responsible. I n certain portions of the gasoline the boiling points of the aromatics and the most highly branched paraffins do not coincide, and in gasolines where the aromatic content is small the effect is even more pronounced because of naphthenic hydrocarbons. This has been found in other gasolines to be described later. It is now possible to produce by fractional distillation fuels containing concentrated portions of branched hydrocarbons, particularly paraffins, but also naphthenes and aromatics where the proportions are several fold greater than in the original gasoline; these materials are characterized as having high octane number, high blending value, and high lead susceptibility. By combining efficient fractional distillation and efficient fractional extraction, it is possible to extend further the scale of knock ratings and the volume of suitable fuel. In this way marked progress can be made toward reducing gasoline, partially a t least, to a list of chemical substances. As this work progresses it is quite probable that greater quantities of gasoline will find use in special solvents and in chemical manufacture.
Literature Cited (1) Campbell, J. M., Signaigo, F. K., Lovell, W . G., and Boyd, T. A , IND. ENQ.CHEW,27, 593 (1935) ; other references are cited. ( 2 ) Edgar G., Calingaert, G., and Marker, R. E., J. Am. Chem. Soc., 51, 1483-1540 (1929). (3) Fenske, M. R., Quiggle, D., and Tongberg, C. O., IND. ENO. CHEM.,24,542 (1932). (4) Garner, F. H., Evans, E. B., Sprake, C. H., and Broom, W. E. J., World Petroleum Congr., London, 1933, Proc. 2, 170. (5) Henderson, L. M., and Ferris, 5. W., U. S. Patent 1,868,102 (July 19,1932). (6) Lovell, W. G., Campbell, J. M.,and Boyd, T. A., IND.ENQ. CHEM.,23,26 (1931). (7) Quiggle, D., Tongberg, C. O., and Feneke, M. R., IND.ENO. CHEM.,Anal. Ed., 6,466 (1934).
RECEIVED July 24, 1935. Presented before the Division of Petroleum Chemistry a t the 89th Meeting of the American Chemical Society, New York, N. Y , April 22 t o 26, 1935.
ZINC-INDIUM ALLOY SYSTEM CURTIS L. WILSON A N D ETTORE A. PERETTI Montana School of Mines, Butte, Mont.
NDIUM alloy systems which have been investigated and reported in the literature aye: lead-indium ($), thallium-indium (4), tellurium-indium (2), copper-indium ( B ) , and silverindium ( 7 ) . Certain alloys of gallium ( I ) , zinc (5), and selenium (8) have been studied, but the equilibrium diagrams of these elements with indium do not appear to have been published. I n preparing the alloys, electrolytically purified indium obtained from zinc-roaster flue dust was used. The metal was first extracted by dissolving the flue dust in hydrochloric acid, separating group I1 with hydrogen sulfide, and treating the filtrate with zinc dust. Zinc and copper were removed with ammonia, and after repeated treatments the indium was
recovered as indium hydroxide or sulfide, taken into solution and then deposited eleEtrolytically upon 'steel cathodes (8). The zinc used was Anaconda electrolytic zinc. The alloys were made by melting the correct proportion of eachmctalseparately and then pouring them together, constantlystirring the mixture, and remelting in carbon crucibles to obtain cooling curves. At the lower temperatures there was practically no loss by oxidation or volatilization. At higher temperatures the melts were protected from oxidation by charcoal. Readings were obtained by means of mercury thermometers, calibrated by the U. S. Bureau of Standards to read to the closest 0.2"C., and an iron-constantan thermocouple. Thirty alloys were made and examined. The combined cooling curves show the equilibrium diagram as represented in Figure 1. Figure 2A is a photomicrograph of electrolytic zinc etched with a 10 per cent solution of nitric acid; the grain boundaries are very sharp. This can be compared with Figure 2B, a photomicrdgraph of a n alloy containing 1.98 per cent indium and 98.02 per cent zinc. It
