I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
September, 1924
the compensating device a t this point, using a slightly larger water jacket to enable inserting the compensator alongside the measuring tube. The accuracy of the single column mercury meniscus used
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in this apparatus is as great as that of the 2-level adjustment used on the Petermen tube, and much more delicate and accurate than the wide 2-bulb Tutwiler modification of the Petermen compensator.
Solubility of the Petroleum Hydrocarbons' By C. F. Mabery CASESCHOOL OF APPLIEDSCIENCE, CLEVELAND, OHIO
B
ESIDES the solubility of the petroleum hydrocarbons in one another, they are generally characterized by insolubility under different conditions in single solvents. It is only with variable mixtures of ether, in which, except the last residues of the asphaltic crudes, these hydrocarbons are all extremely soluble, and alcohol, in which they are a t most only slightly soluble, that efficient solvents may be made capable of a good separation of the homologs andisologs. A method of separation based on these differences in solubility was employed as described in an earlier paper on this subject.2 While the results then presented were sufficient to indicate wide variations in solubility, no attempts were made in that work to show precisely these differences in the hydrocarbons separated. I n taking up the study of the Midcontinental oils-using this term in a broad sense to include Oklahoma, Wyoming, Illinois, and Ohio crudes-and other southern oils, it seemed desirable to ascertain with greater precision the extent to which this method may be relied on for the separation of the individual hydrocarbons. By reference to the paper cited it appears that, starting with a given quantity of oil, the solvent dissolves out first in successive portions all the series, graduated in solubility, and after a sufficient number of repetitions the fractions show a similar graduation in physical properties. Then from this mixture of homologs and isologs, with the use of a properly graded solvent, the isologs, the lighter D-hydrocarbons, may be fractionated from the less soluble homologs, the H-hydrocarbons.
METHODS The solvent was tried in two formsether 50, alcohol 50; and ether 100, alcohol 50, by volume; the former on fractions in the most soluble end, and the latter on the fractions of the least soluble end. For the manipulation of the solution two common test tubes with side tubes were used, as shown in the figure. I n the tube B, closed by a cork and rubber cap, a quantity of the oil with ---the solvent was allowed to stand a t 20" -C. for 2 hours, or until it settled clear after sufficient agitation. The tube A , also closed with a stopper and cap, was weighed, cooled to the same temperature, attached to the tube B as shown, and after a portion of the solution in tube B was decanted into it, again closed with its cap and weighed. The cork and cap were then removed and this tube was heated in an air bath to 110" C. for the removal of the solvent and moisture (from the solvent), and the tube and oil weighed. By this means it was possible to prepare and weigh a saturated solution of the solvent without loss. ~~~
1
Received July 7, 1924.
* Mabery, THISJOURNAL,
16, 1233 (1923).
I n making the saturated solutions care is necessary in limiting the amount of the oil, especially in the 100-50 solvent, for a large excess of the oil is liable to dissolve the ether away from the alcohol. On this account the solubility of the Cabin Creek Fraction D-7 in the 100-50 solvent could not be determined. This often happens in extractions with too rich a solvent. The addition of more alcohol attracts the ether from the oil so quickly that the stopper may be blown out of the bottle.
RESULTS The results obtained by this method are recorded in the table, which includes fractions of the oils described in the former paper together with those from an Oklahoma oil and from a Gulf Coast, Texas, oil. From the last two oils, a description of which has not been published, fractions were separated from distillates, -300" C. 30 mm., and from residues of these distillates. As in the earlier paper, the numbers of the fractions are taken from the H and D series, No. 1, the most soluble end, to No. 10 or 13, the least soluble end. SOLUBILITY OF THE PETROLBUM HYDROCARBONS Composition of sol- Solubilty Fraction vent, ether-alcohol Per cent 4.33 H-2 50-50 Cabin Creek (f300' C., 30 mm.) 15.86 D-2 2.19 H-7 4.86 D-7 42.53 100- 50 H-7 9.60 D-7 (Ether dissolved by oil) 6.10 H-1 50-50 Rosenbury ($300' C., 30 mm.) 19.45 D-1 4.64 H-5 11.26 D-5 7.25 H-2 Mecca (+30O0 C., 30 mm.) 9.66 D-2 7.58 100-50 H-7 13.53 D-7 Sour Lake, Texas (+300° C., 7.26 50-50 H- 2 30 mm.) 16.66 D-2 7.27 50-50 H-5 22.04 D-5 10.52 100-50 H-5 25.62 D-5 12.55 5C-50 H-I. Russian (+300° C., 30 mm.) 17.60 D-1 3.25 100-50 H-5 6.94 D-5 28.27 H-2 Oklahoma (-300' C., 30 mm.) 35.30 D-2 12.22 H-9 30.39 D-9 50-50 8.40 H-2 Oklahoma (+300° C.,30 mm.) 16.54 D-2 4.72 H-13 6.82 D-13 11.00 100-50 H-13 15.82 D-13 Gulf Coast, Texas (-300' C., 20.24 60-50 H-2 30 mm.) 29.28 D-2 9.83 50-50 H-8 15.54 D-8 9.16 H-2 Gulf Coast (+300° C . , 30 mm.) 18.84 D-2 6.52 H-10 12.20 D-10 4.73 100-50 H-13 9.57 D-13
