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Use of Organic Solvents for the Extraction of HighSulfur Oils from Crude Petroleum*'2 Preliminary Paper Gladys E. Woodward3 CHEMICAL LABORATORY OF THE COLLEGE OF LIBERAL ARTS, NORTHWESTERN UKIVERSITY, EVANSTOX, ILL.
M O S G the many peculiarities and difficulties of re- per cent sulfur, respectively. Thus, acetaldehyde seemed to search on sulfur compounds in petroleum, not the have a slightly more selective action for the sulfur constituleast is the fact that the enormous amount of research ents, as well as being more easily removed from the extract which has been done and is being done in this important field because of its greater volatility. By this process of elimination acetaldehyde was selected has resulted in very little publication. This is undoubtedly because most of the results have been distinctiy negative in for a large-scale extraction of the crude. Three successive character. Apparently hundreds of investigators have had extractions of the crude with fresh portions of acetaldehyde the idea of extracting crude petroleum with various solvents and subsequent evaporation of these extracts produced oils containing w r y nearly the i n an attempt to remove the same amounts of sulfursulfur c o m p o u n d s . Y o The miscibility of sixty-one organic liquids with 2.77, 2.77, and 2.68 per cent, publication has been made Inglewood crude petroleum has been determined respectively. The fractionaof their results, h o w e v e r . qualitatively. With several of these liquids the miscition of these was continued The reason for publishing bility has been determined quantitatively. by extracting with acetalthe present paper a t this The relative amounts of sulfur extracted by several dehyde. An oil with 2.97 time is t o put on record some of these solvents have been determined. per cent sulfur was obtained. definite results, even though A fractional extraction of 3.5 liters of the Inglewood This extract was likewise they are far from hopeful as crude petroleum has been carried out with acetaldefurther extracted, but the means of solving the probhyde as extractant. In three extractions the sulfur oil obtained had increased lem of removing sulfur comcontent was increased only from 2.30 to 3.01 per cent. only t o 3.01 per cent sulfur. pounds from petroleum in a Therefore, this is not a practical method of isolating Thus, as each succeeding exform in which they can be the sulfur compounds. tract is extracted, the inidentified. crease in sulfur becomes less. The present research was Furthermore. the extraction undertaken with the hope that sulfur compounds present in crude petroleum might be becomes more difficult as the material becomes more misciextracted from it by means of organic solvents. The solvent ble with the acetaldehyde. These oil fractions had been obtained from the extracts by to be used must not mix completely with the oil. To this end, therefore, experiments were conducted with a large evaporation a t 40" C. The dissolved acetaldehyde was also number of readily available organic liquids to determine removed from the residual crude in the same manner and the approximate degree of miscibility with the petroleum. the residue was also found to have increased in sulfur content For this work a petroleum containing 2.30 per cent sulfur from over the original crude-however, to only 2.54 per cent. This indicated that non-sulfur material had been lost during the Inglewood field in California was useda4 A quantitative determination of this solubility was then the evaporation, thus increasing the sulfur content of both made with several of these liquids which appeared to extract extract and residue. It was thought that the greater increase material from the oil. . The extract layers of each were ana- in sulfur content in the extract might have been due to the lyzed for sulfur. I n no case was a large amount of sulfur loss of more hydrocarbons during the evaporation of the more found in the extract. Furfural, absolute ethyl alcohol, and dilute acetaldehyde solution. It was proved, however, that acetaldehyde showed the highest concentrations of sulfur, the increase was due to an actual concentration of the sulfur with 0.42, 0.36, and 0.31 per cent, respectively. I n order t o constituents by extraction. To remove the possibility of isolate the material extracted, the solvent must be easily re- further loss of hydrocarbons during evaporation, a small moved from the extract. This was possible in the case of sample of the crude was first evaporated to constant weight a t ethyl alcohol and acetaldehyde and, when the extract had been 40" C., then an extraction made and both residue and extract evaporated a t 40-50" C., the oils left contained 2.19 and 2.37 were again evaporated to constant weight a t this same temperature. The residue was then found to have decreased 1 Received March 28, 1929. Revised paper received October 28, 1929. * This paper contains results of an investigation carried out as part slightly in sulfur content, while the small amount of extract of Project 17 of the American Petroleum Institute research program. Finanhad increased considerably to 3.21 per cent. cial assistance in this work has been received from a research fund donated Although it has been shown that concentration of the sulfur by the Universal Oil Products Company. This fund is being administered compounds by extraction is possible, nevertheless, the experiby the American Petroleum Institute with the cooperation of the Central ments on a larger scale as mentioned above show this method Petroleum Committee of the National Research Council. Frank C. Whitmore is director of Project 17. to be too tedious for practical use. The experimental data 8 Research Fellow, American Petroleum Institute. obtained during this work are given below.
A
This oil was obtained from the Inglewood field in California through the courtesy of the Universal Oil Products Company of Chicago. "This crude oil came from Standard Oil Tank No. 9461, November 19, 1926, and represents the regular pipe-line run from the Inglewood field. This field was producing about 40,000 barrels per day at that time. The production comes from an average depth of about 2000 feet below surface. The producing formation is Pliocene marine sand, and the general structure is an anticline faulted on one side "
Miscibility of Organic Liquids with Inglewood Crude Petroleum
The solubility tests were carried out in test tubes. Two parts of oil by volume to one of organic liquid were shaken together. In most cases the separation into layers was
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easily visible after a few hours. Where no layers were visible, a Westphal balance was used to determine the homogeneity of the mixture. In a few cases, as indicated in Table I, layers of different density were discovered by this means. Usually, however, after standing several days the layers could be detected by the eye. Table I contains the results of the solubility tests of the oil in organic liquids. The color of the solvent layer is also given, since the depth of color is another indication of the relative solvent action on the oil.
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the extraction. The solvent and oil were mixed by mechanical stirring in graduated centrifuge tubes. These tubes were then centrifuged to separate the layers rapidly and completely. The line of separation of the layers was read on the scale of the tube. The solvent layer was drawn off with a special siphon and analyzed for sulfur. I n a few cases, as given in Table 11, the solvent was evaporated from the extract in order to obtain the material extracted that it also might be analyzed for sulfur. The second and third extractions were made with fresh portions of solvent on the residue from the preceding extraction.
T a b l e I-Solvent Action on Inglewood C r u d e P e t r o l e u m EFFECT^ COLOROF SOLVENT LAYERBY LIGHT SEBSTANCE T a b l e 11-Quantitative Solvent Action o n Inglewood C r u d e Retlected Transmitted P e t r o l e u m (2.30 P e r C e n t S ) s IN Alcohols: OIL S IN MATERIAL Methyl alcohol I Yellow to brown Yellow to brown SOLVENT (10 cc ) USED EXTRACT EXTRACT EXTRACTED Ethyl alcohol Green Red to brown E n-Propyl alcohol Very dark green Opaque Eb CC. Cc. Per cent Per cent Isopropyl alcohol I Yellow green Orange Furfural: n-Butyl alcohol Very dark green Opaque Eb 1st extraction 20 0 11 3 0 42 sec-Butyl alcohol S 2nd extraction 15.0 11.9 ter-Butyl alcohol Very dark green Opaque E Acetaldehyde: n-Amyl alcohol S 1st extraction 0.31 20.0 7.5 Isoamyl alcohol S 2nd extraction 0.42 17.5 11.0 2.37 ter-Amyl alcohol S 3rd extraction 11.0 11.0 -Ethylene glycol PS Clear and colorless Ethyl alcohol (abs.): Propylene glycol I Pale yellow Pale yellow 1st extraction 20.0 11.1 0.36 Clear and colorless , Glycerol PS 2nd extraction 0.27 13.0 13.0 2.17 Hex a1in S 3rd extraction 0.22 2.19 10.0 13.0 Red Furfuralcohol I Green Ethyl alcoho! (95%): Very dark red Diacetone alcohol Green I 1st extraction 20.0 10.5 0.169 Citronellol 2nd extraction 0.145 S 19.0 12.0 3rd extraction 0.137 14.0 12.0 Aldehydes: 0.125 Glyceryl triacetate 2 0 . 0 10.6 Red Acetaldehyde PS Dark green 0.145 Glycol diacetate 20.0 10.1 Butyraldehyde S 20.0 1 0 . 0 0 ,073 Methyl alcohol Heptaldehyde S Glyceryl diacetate 20.0 10.0 S Benzaldehyde Furfuralcohol 20.0 1 0 . 0 IC Brown Opaque Cinnamaldehyde Isopropyl alcohol 20.0 9.5 Brown Opaque Anisaldehyde EC Acetol in methanol ( 5 0 % ) 20.0 9.5 Crotonaldehyde S Diacetone alcohol 20.0 9.1 Citral S Ethyl acetoacetate 20.0 8.5 Red-brown Brown Furfural E Methyl acetate 20.0 8.0 Ketones: 4Glycerol 20.0 4.5 Dark green Opaque Acetone PS Ethyl methyl ketone S Methyl amyl ketone S Fractional Extraction with Acetaldehyde Acetophenone S Ethers: Three and one-half liters of the Inglewood crude petroleum S Ethyl ether Acetal S (containing 2.30 per cent S) were stirred mechanically for Aniso1e S half an hour in a closed vessel with 3.5 liters of acetaldehyde. Esters: Yellow I Pale blue-green Methyl acetate The upper acetaldehyde layer was drawn off through a special S Ethvl acetate stopcock. All the acetaldehyde possible was removed by ~So&nylacetate S Opaque Gray-brown EC Ethyl oxalate distillation on a water bath a t 40" C. The remainder was Yellow to red Yellow-green I Glycol diacetate Deep yellow Pale green Glyceryl triacetate E removed by allowing it to evaporate from an open dish on an Acids: electrically heated stove kept approximately a t 40" C. The IC Very dark green Opaque Acetic acid S Propionic acid oil thus obtained from this extract contained 2.77 per cent Halogen compounds: sulfur. PSC Chloroform PSC Carbon tetrachloride The residual crude was extracted twice further in a similar S n-Butyl chloride manner with one-half volume of acetaldehyde. Although in S Ethylene dichloride the first extraction equal quantities were used, from the preI Nitriles: Deep yellow Pale blue-green Acetonitrile liminary experiments it was calculated that these quantities Compounds with mixed functions: Red would make a proportion of 2 to 1 by volume of oil saturated Ethyl acetoacetate I Green Pale yellow J Glyceryl monoacetate I Pale yellow-green with acetaldehyde to the acetaldehyde. In the second and Yellow ,/Glyceryl diacetate I Yellow green Red _.._ Lactic acid I Dark green third extractions oils containing 2.77 and 2.68 per cent sulfur, Opaque Methyl chloroacetate I Gray-brown Opaque respectively, were obtained. Dichloroacetic acid IC Dark green Opaque \i Ethylene chlorohydrin Gray-brown On attempting to fractionate these extracts by further exOpaque Dichloroethyl ether Dull green Yellow I Acetol I Yellow traction, it was found that they were completely miscible Deep yellow dDiethylene glycol I Dull blue-green Orange Triethylene glycol I Green with acetaldehyde when mixed in the previously used proporYellow Aldol PS Yellow tion. With the first extract, however, there was a separation Hydrocarbons and heterocyclic compounds: Tetralin S into layers when mixed in the proportions of 1 to 2, 1 to 3, and Furan S 1 to 4 of acetaldehyde. These layers separated better a t Quinoline S temperatures of -10" to -20' C. The bulk of the oil exa S = completely soluble, PS = partially soluble (volume solvent layer decreased) I = insoluble (volume solvent layer appears constant), E = tract was therefore extracted with four volumes of acetaldeextracts (;ohme solvent layer increased). b Dissolves all but a trace of the oil. hyde a t -10" C. The new oil obtained from this extract c Layers not readily visible; detected by difference in density by contained 2.97 per cent sulfur. This oil extract was more Westphal balance.
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Relative Extraction of Sulfur from Petroleum by Organic Liquids
A few of the liquids which were not completely miscible with the oil were used in quantitative experiments. The increase or decrease in volume of the solvent was determined, and in some cases the sulfur content of the solvent layer after
miscible with acetaldehyde than the previous extract. It could be extracted only in the proportions of 1 to 2 and 1 to 3 of acetaldehyde. An extraction in the latter proportion gave an oil containing 3.01 per cent sulfur. The fractionation in this manner was carried no further. When the residual crude from the three extractions was heated a t 40" C., as were the extracts, to remove the acetalde-
December, 1929
INDUSTRIAL AND ENGINEERING CHEMISTRY
hyde, i t was found to contain 2.54 per cent sulfur. This was more than the original crude had contained. This increase was due to loss of some of the lower boiling hydrocarbons while heating a t 40" C. Therefore, a small sample (about 50 cc.) of the original crude was heated to constant weight before extracting. I n this treatment the sulfur content increased to 2.76 per cent. After an extraction with an equal volume of acetaldehyde, the residue contained 2.71 per cent sulfur, and the material extracted contained 3.21 per cent. Thus
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it is shown that the higher sulfur content of the extract in this experiment was due to a slight concentration of the sulfur compounds by extraction. Owing to the viscosity of the oil, it did not seem practical to treat a large amount of the crude in this way before an extraction. But since the sulfur content of the material extracted is higher than in the residue, even though both are higher than originally, it seems certain that here also the concentration of the sulfur compounds has resulted from the extraction.
Heats of Fusion of Some Paraffin Hydrocarbons' George S. Parks and Samuel S. Todd DEPARTMENT OF CHEMISTRY, STANFORD UNIVERSITY, CALIF.
N SPITE of the great importance of the paraffin hydro-
40 cc. capacity, the entry tube of which could then he closed carbons, the heat of fusion of only one of these, methane, by a small screw plug. This capsule was suspended by a hook has been reported in the literature up to the present time. mechanism within the heater, which was a hollow aluminum I n the past few years the lack of such data has proved a serious cylinder wound on the outside with a nichrome heating coil. handicap to several investigators, who have found it necessary By proper regulation of the current through this coil, the to make rough guesses of heats of fusion of hydrocarbons, heater and capsule could be brought to any desired temperathereby introducing a factor of uncertainty into their results. ture up to 300" or 400" C. A small, two-element, copperPartly to remedy this situation the present investigation was constantan thermocouple ran down a tube in the center of undertaken a couple of years ago; and in an experimental the capsule and thereby measured the temperature of the study the heats of fusion of four compounds-vis., hexa- hydrocarbon sample to 0.1" C. A similar thermocouple, methylethane (CsHls), n-eicosane (CwHhz), n-pentacosane placed outside, served to determine the adjoining temperature (C2SH52),and n-tritriacontane (CsaH@)-have been measured. within the heater and to provide a check upon the attainment of thermal equilibrium. The results, when combined with similar data recently At the proper time in the The heats of fusion of hexamethylethane, n-eicosane, o b t a i n e d i n another recourse of a determination, n-pentacosane, and n-tritriacontane have been meassearch in this laboratory, t h e h e a t e r a n d contents ured by a method of mixtures. These results, when furnish some interesting inwere moved by a suitable combined with similar data obtained in other investiformation on the heats of m e c h a n i s m to a position gations, have furnished the basis for a general study of fusion of paraffin hydrocardirectly above the calothe heats of fusion of paraffln hydrocarbons. By means bons. rimeter, and the capsule, reof an empirical equation the fusion values of thirtyleased on the instant by an Method and Apparatus three normal paraffins have been calculated. In genautomatic dropping device, eral, branched isomers show smaller heats of fusion fell into the c a l o r i m e t e r . I n principle the method than the normal compound, but the effect cannot be T h i s c a l o r i m e t e r was a of mixtures was employed. predicted quantitatively. n i c k e l - p l a t e d copper jar A steel capsule, containing a weighed sample of the c o n t a i n i n g a b o u t 1500 grams of water, a Beckmann h y d r o c a r b o n u n d e r investigation, was first brought to a given upper temperature thermometer calibrated by the U. S. Bureau of Standards, a in an electric heater and was then dropped into a water small stirrer of the propeller type, and a receiving holder for calorimeter, initially a t 25" C. The temperature rise of the the capsule. It was suspended by three Bakelite hooks water in the calorimeter was measured, and from this result within a second jar, 3.0 em. larger in diameter. These two the decrease in the heat content of the hydrocarbon sample jars rested in a water thermostat, kept a t 25" C., and were was calculated. By the use of various upper temperaturescovered with a double-walled copper cap filled with the therfor instance, one somewhat below the melting point of the mostat water. Initially the calorimeter and thermostat sample, a second slightly above, and a third perhaps 30 or were a t practically the same temperature, but after the fall 40 degrees above the melting point-adequate data could be of the capsule there was usually a difference of 1 to 3 degrees obtained for the calculation of the heat of fusion of the sub- and, accordingly, the Regnault-Pfaundler method was used stance as well as of its interval specific heats in both the in determining the heat loss to the thermostat during this crystalline and liquid states. part of a run. The heat capacity of the empty capsule over The apparatus had been constructed for an earlier research the temperature ranges involved was measured in a separate by Wm. M. Marker (S),to whom the writers are indebted for series of determinations. Throughout the investigation the the privilege of using it in the present investigation. It had usual devices and precautions of good calorimetric procedure been built in general along the lines developed and used by were employed. numerous investigators in the past, and therefore no detailed To give the reader a concrete example of the reproducibility description is necessary here. The hydrocarbon sample was of the method with our apparatus, we present in Table I the introduced as a liquid into a cylindrical steel capsule of about results of five determinations of the specific heat of crystalline hexamethylethane over practically the same temperature 1 Presented before the Division of Petroleum Chemistry a t the 78th range. It will be observed that the greatest deviation from Meeting of the American Chemical Society, Minneapolis, Minn , September the mean value is 1.0 per cent. 9 t o 13, 1929.
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