INDUSTRIAL AND ENGINEERING CHEMISTRY
128
Vol. 19, No. 1
The Composition of Gasoline as Indicated b y Close Fractionation' By J. B. Hill, L. M. Henderson, a n d S. W. Ferris THEATLANTIC REFINING Co., PHILADELPHIA. PA.
I
NTEREST in the chemical composition of gasoline has been intense since detonating characteristics have become important and have been shown to be linked with chemical composition. Considerable work has been done from time to time on the isolation of pure compounds from gasoline and nearly every conceivable hydrocarbon which might plausibly be present has been identified. This work has, however, furnished very little information on the chemical composition from aquantitative standpoint. Various chemical and physical methods have been devised to determine the proportions of the various series of hydrocarbons present and these are of undoubted value, although only more or less accurate. CrossJ2among others, has suggested as an indication 'of detonating characteristics a distillation of the gasoline with slight fractionation and the plotting of a curve showing boiling point of the fractions against specific gravity, high specific gravity indicating good detonation characteristics. The fractionation in such tests is not sufficient to give other than a smooth curve, and therefore no real light is thrown on the composition of the gasoline. The work herein described was prompted by the thought that a study of these gravity-boiling point curves, produced under efficient fractionation, might prove interesting.
data for the California gasoline are given as typical, in Table 11, and data for all four products are shown graphically in Figures 1, 2, and 3. The boiling points given are the 50 per cent points on the distillation. The temperatures are not corrected. T a b l e 11-Laboratory
F r a c t i o n a t i o n of California Gasoline ANILINB POIXT
... ... ...
59.0 40.5 42.0 52.0 54.0 48.5 44.5 34.0 35.0 48.0 58.0
g;:
49.5 42.5 38.0 39.5 46.5 50.5 54.5 54.5 51.5 50.0 48.0 47.0 49.0 50.5 52.0 53.5 53.5 54.5
Experimental
Four gasolines of known history and source were used: (1) Pennsylvania, prepared by straight running from a typical Pennsylvania crude. (2) hlidcontinent, a straight-run product from a typical highgrade Oklahoma crude. (3) California, a straight-run product from California crude. (4) Cracked, a product cracked from midcontinent gas oil by the Cross process. T a b l e I-Assay PER CENT
Distillation of Gasolines
P E N N ~ Y L V A N IMIDCONTINENT A CA:IFORNIA C. C. C.
CR~CKED C. ~~
Over 5
10 20 30 40 50
60 70 SO 90
95 Dry
51 77 88 104 115 127 138 149 160 173 197 215 228
55 80 90 104 116 127 139 150 162 175 197 215 229
46 70 82 105 119 128 139 150 162 177 194 210 223
42 64
81 ._
104 120 131 140 151 160 170 184 192 199
The tests on these four products are given in Table I. Two-liter samples of each of these products were fractionated by means of a 5-fOOt Snyder column with 47 sections run adiabatically with a controlled reflux of about 5:l at the top. The distillate was collected in fractions representing 2.5 per cent of the charge. These fractions were tested for specific gravity, aniline point (critical temperature of solution), refractive index, and distillation range using the A. S. T. M. method with the substitution of short range thermometers graduated in 0.2" C. for the A. S. T. M. thermometer. The 1 Received August 28, 1926. Presented before the Division of Petroleum Chemistry at the 72nd Meeting of the American Chemical Society, Philadelphia, Pa., September 5 to 11, 1926. 2 Kansas City T e s t i n g Lab., Bull. 19 (1925).
I n order to obtain information on even closer fractionation a 10-gallon portion of the California gasoline was fractionated, using a 16-foot column packed with glass rings and provided with electric insulation and controlled reflux. This column gave about the same efficiency as the &foot Snyder column. Five selected fractions from this run were refractionated with the Snyder column into 12.5 per cent cuts and the properties of these cuts determined. The data are given in Table I11 and are shown graphically in Figure 4. The close distillation ranges of these cuts, which are as low as 1.2" c.,as well as the ranges of the primary laboratory distillations, are noteworthy. Discussion
All of the curves show a surprising regularity of peaks and troughs, these corresponding for any one gasoline very closely, as would be expected, on the specific gravity, aniline point, and refractive index curves. The peaks-i. e., high specific gravity, high refractive index, and low aniline pointshow a high concentration in these fractions of the more naphthenic hydrocarbons. The troughs conversely show a higher concentration of the paraffins. For purposes of comparison, curves showing the properties of the various series of hydrocarbons as taken from the literature are shown in the figures. The fact that all four gasolines show their peaks and troughs in amroximatelv the same Dlaces is interesting. This may indiiite that th"e gasolines Eontain the same preponderant
.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
January, 1927
129
5 0 X B o i ~ i ~POINT G
SPECIFIC GRAt'ITY~t2Ot ."i
ANILINE POINT
-
-
134-
133
'
I
'
I
)
'
)
! 1
1
1
1
I
I
I
I
l
l
I
.50%6O/LING P O I N T - ' C
F i g u r e 1-Variation
of S p e c i 6 c G r a v i t y g a n d Aniline P o i n t w i t h Boiling Point
T a b l e 111-Laboratory
Redistillation of Primary Cuts frorn:California Gasoline
h'UMBER
OF
50% BOILING BOILING R ~ N G E POINT C.
CUT
Charge: Primary c u t 5 cut 1 2 3 4
5 6 7 7
79 70.5 72.0 75.1 78.4 82.6 88.8 92.2
Charge: Primary cut cut 1 2 3
2.8
S
Charge: Primary cut 10 cut 1 2 3
Charge: Primary c u t 13 cut 1 2 3
Charge: Primary cut 18 cut 1 2 3 4
5
6
7 8
12.5 2.6 3.i 4.4 3.2 4.6 2.5 3.2 7.2 7.3
101.8 97.9 99.4 99.8 100.6 101.9 103.6 105.8 108.2 117.5 110.7 116.0 117.4 118.4 119.3 119.8 120.8 123.6 135.9 132.2 134.0 134.8 135.4 136:2 137.5 140.2
1.8 1.8 1.7 2.6 2.7 2.6 7.4 5.6 4.0 2.8 2.1 2.1 2.4 1.8 4.6 5.7 9.6 4.8 3.2 1.8 1.4 1.2 1.6 4.0 3.4 4.6 3.3
goy?j 0.7413 0.7276 0.7403 0.7514 0.7593 0.7538 0,7292 0,7258 0.7296 0.7406 0,7301 0.7264 0.7235 0.7254 0.7242 0.m6 0.7400 0.76'35 0.75ii 0.75.57 0.7614 0.7710
p?.
0. 0. ,884 0 . 7894
2.3
0.7446 0.7527 0. 7409 0.7389 0.73!91 0.7419 0.7451 0.74!)9 0.7501 0.7868 0.7803 0.7860 0.7880 0.7888
1.5
o.iibs
2.5
...
1.8 6.9
A;i?kc.:E
0.7887 0.7780
...
37.5 32.25 32.50 34.0
39.0 54.0 57.0
...
46.0 53 55.25 57 56.5 56.5 56.25 47.5
...
43.3 40.75 40.5 37.5 32 26 21.5 20.0
...
49.0 59.0 61.0 62.0 60.5 59.0 5S.O 57.5
...
40.5 37.5 36.75 35.75
...
35.0 37.0 46.5
compounds, diflering only in their proportions. It will be noted, however, that the troughs coincide very well with the boiling points of the normal paraffin hydrocarbons and are therefore probably produced by these same compounds in each gasoline, the peaks representing merely the portions of the curves between the troughs. This would tend to confirm the observation, repeatedly made, of the relatively small quantities of the paraffins other than the straightchain members of the series present in gasoline. It will be noted that in the specific gravity curl-e the cracked gasoline falls considerably below the California, in the refractive index curve the two are almost the same, and in the aniline point curve the cracked is the higher (lower aniline point). This is doubtless caused by the fact that the olefins, in which the cracked gasoline is rich, differ much less from the hydroaromatics in the California gasoline in refractive index than in specific gravity, and have an actually greater depressive effect on the aniline point. The deviation of the Pennsylvania curves from the paraffin curves is interesting in view of the common characterization of Pennsylvania naphthas as paraffinic. The peaks from the Pennsylvania fraction appear to be more "naphthenic" than the troughs from the California gasoline. In Figure 3 the California specific gravity curve is shown alone, with various points indicated representing hydrocarbons which have properties close to the curve. This is merely a matter of interest, and the authors do not intend t o imply that these compounds are present. I n Figure 4, showing the effects of refractionation on the peak and trough cuts, the expected effect is realized-viz., the troughs are considerably lowered and the peaks raised. It is interesting to note that while peaks occur at the boiling points of benzene and toluene they are high enough to rep-
I S D U S T R I S L A N D ENGI,VEERING CHEMISTRY
130
resent only small concentrations of these compounds even if the peak is considered as being solely due to these compounds. For example, the highest gravity fraction at the benzene boiling point (80" C.), represent,ing 0.31 per cent of
Vol. 19, No. 1
the gasoline, has a specific gravity of 0.76. Assuming that this is a mixture of benzene (sp. gr. 0.88) and hexane (sp. gr. 0.66) only, it would contain only 45 per cent of benzene, calculated from its gravity or 0.14 per cent based on the gasoline charged. The results of this work are of considerable speculative interest but are not considered as warranting conclusions.
CALIFORNIA G A S 0 L IN€
1
60
0
10
1
1
1
1
zo 30 40 so
I
60
70
do
90
IM
110
bao
I% 140
50% B O I L I N G P O I N T -
F i g u r e 3-California
1%
160
170
Is0 1%
60 m
'C
Gasoline
Figure 4-Refractionation
of California F r a c t i o n s
Rubber as a Solution of Corrosion and Abrasion Problems' By H. E. Fritz2 MECHANICAL SALES DEPT.,THEB. F. GOODRICH RUBBERCo., AKRON, OHIO
HE chemical industries have long felt the need of corrosion and abrasion resisting materials which, when subjected to general factory conditions, such as shock, vibration, and strain, will be serviceable through long periods of time. Such material would greatly decrease replacement and maintenance and would help to revive many chemical manufacturing processes now in the discard for want of suitable construction substances. Iron and steel or sheet metal, if corrosion-resisting, would be the ideal chemical engineering construction material. As there is grave doubt that such a material will ever be develoDed, we are forced to utilize that which is best suited to our-purpose, regardless of its disadvantages. Rubber or rubber compounds and combinations are often satisfactory from the standpoint of resistance to corrosion, but they have lacked the combination of rigidity and strength than limited. necessary to make their application
T
1 2
Received July 24, 1926. Sales Engineer.
It has been known for some time that hard rubber can be applied to clean metal surfaces with a measure of success from the standpoint of adhesion. It is also a well-known fact that hard and soft rubber can be united with very desirable adhesion. I n this way, by use of a combination stock, fairly good adhesion of rubber to metal was obtained. Materials lined or covered by this process must be classified as fragile equipment, because flexing, shock, strain, differences of expansion, etc., tend to crack or destroy the hard rubber backing. The Vulcalock Process3
The objections t o the old process were the stimulus for the development of a process for attaching soft rubber to metal with sufficient adhesion to insure a perfect union of the two surfaces. The Vulcalock process, in which adhesions up to 700 pounds per square inch have been obtained, makes it possible 8
Canadian Patents 266,967 (1923) and 256,797 (1925).
