a
I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
814
Vol. 18, N o . 8
The Composition of Midcontinent Petroleum' By Charles F. Mabery CASESCHOOL OF APPLIEDSCIENCE,
CLEVELAND,
OHIO
the correct volume after the solution has been cooled, the MPROVEMENTS in solvent fractionation are extreatment of the oil with solplained. Most of the lubricants undergo vacuum vent of the same composidistillation without great decomposition. The average tion is not repeated. If the percentages of carbon and hydrogen in oils from the fraction is too small, the exdifferent fields and also the refractive indices differ traction is repeated until the essentially. In the same oils marked variation is shown desired volume of oil has between viscosity and specific gravity in the D and H been extracted. series. In all petroleum the more general and the best T h e s e c o n d fraction is lubricant hydrocarbons are those of the series CnHzn-4 separated similarly, the perand CnHzn-8. The series lower in hydrogen gradually c e n t a g e of e t h e r in the fall off in stabilityas theasphaltic series are approached. mixed solvent being inThe behavior of petroleum lubricants on a standardcreased by the necessary ized frictional testing machine shows the comparative amount. Succeeding fratSeparation by a Solvent strength of the individual molecules to resist breaktions of first set are ing stress as indicated by the appearance of smoke and separated in a similar way. Questions concerning the final rupture. The first fractions sepao p e r a t i o n of the method r a t e d , w h i c h contain the which have been received ' hydrocarbons m o s t s o l u since the publication of the previous paper indicate that the first description was not suffi- ble, are designated as the upper end, while the undissolved ciently explicit in details. Furthermore, certain improvements residue, the last fraction, and the fractions before it are called have made the separations more complete and have indicated the lower end. I n the later work the fractions have been obtained from the that it is only a matter of sufficient repetition, as in fractional distillation, to separate closely the individual constituents. hot decanted solution by cooling to 0" C. and decanting the The method of separation now applied to both crude oils and solvent. This solvent is then used, after adjusting the comlubricants consists first in removing from the sample what will position, for extracting the next fraction. I n the earlier distil below 300' C. under a pressure of 30 mm., and noting work2 the first set of fractions were fractionated by starting the temperature at which distillation begins, the percentage a t the lower end. Better results, especially in the heavier of distillate and residue, the specific gravity, and the vis- oils, have been obtained by the reverse operation, and this cosity as measured in a Saybolt viscometer and in an Ostwald method has been used in the work reported here. The first fraction a t the upper end is extracted in a separatube. A sufficient quantity of the crude petroleum or lubricating tory funnel of suitable size with a solvent of such composition oil is distilled from a large Engler distilling flask to insure that it will dissolve a t the boiling point 5 to 10 per cent of that the residual oil will weigh 1500 to 2000 grams. For the fraction. The manipulation is the same as that described convenience, the cooled residual oil is divided into four for preparing the first set of fractions. The hot solution is nearly equal portions, and each is placed in a 1-liter pear- decanted and cooled to 0' C. in order to prove that the deshaped separatory funnel having a short stem. These four sired volume has been extracted. The solvent and separated oil are added to the next fraction, and the extraction is 1 Received June 29, 1925. * TRIS ]OURNAL, 15, 1233 (1923). carried out as before. This treatment is continued until Correction-In Table 111 of this paper occur several errors, not due to all the first set of fractions have been extracted. The fraction the printer, that should be corrected as follows: of oil that separates on cooling to 0' C. the solution from the Rosenbury, D Series should read CaHm-4. lowest fraction of the original set is kept separate as an addiMecca, H Series, No. 7, should read CmHm, mol. wt. 1674, Series tional fraction of the new series, The extraction of the SUCCnHsn -a4. Sour Lake, H Series, No. 8, should read CtoHm, mol. wt. 1234, Series cessive new series of fractions is repeated as often as is deCnHzn - 20. sired, a new fraction being obtained each time. These addiRussian, D Series, No. 5, should read COOHIII, mol. wt. 1234, Series tional fractions are of relatively small volume. Each time CnHm - 16. ana, are discussed in this p a p e r , a r e specimens of crude Oils and Of lubricants m a d e f r o m t h e m , from oklahoma' Illinois, Texas, and Ohio. Lubricants made from Penn''lvania and West Virginia crudes' described in the former paper,z are also in'luded' were Obtained from prominent oil companies in the different fields.
I
August, 1926
INDUSTRIAL AND ENGINEERING CHEMISTRY
a fractionation is repeated, all the fractions, including those that have been added by earlier fractionations, are included. After five to seven fractionations each of the final fractions is separated into the H and D isologs by the method described in the first paper. Both series are next examined as to specific gravity, molecular weight, and ultimate analysis, and from these results the formulas and series are calculated. The lubricants are separated in a similar manner into fractions containing the hydrocarbons of which they :we composed; the fractions are given a similar fractionation and examination. Without long-continued separations, as in fractional distillation, it cannot be assumed that the individual fractions are given more than an approximate separation, although those of the heavy end, extracted thirty or forty times, must approach the composition of individual hydrocarbons. The most important change in method is downward separation, or from light to heavy consituents, instead of from heavy to light as described in the first paper. I n the medium portions of some crude oils ordinarily included in the lubricant fractions, there appears to be but one series of hydrocarbons, consisting of only a few members. I n others, composed of D and H series, although some of the more soluble D's remain with the less soluble H's, even in downward extractions this behavior does not seriously interfere with a n approximate separation. A feature of this separation by a solvent that is a t first disappointing is the smallness of the fractions thdt separate on CQOhg. Not until an equilibrium of oil and solvent with proper proportions of ether and alcohol is gained by several repetitions do fractions of 10 to 25 cc. or more separate when cold. The narrow limits of temperature restrict the separation, for the highest boiling point of the solvent, 38Oto 40" C., necessitates cooling to 0" C. or below. There are also wide differences in the solubility of crude oils and the lubricants made from them. The least soluble of the lubricants examined were the healy ends of the fraction from the asphaltic base oils. The separations are best made in separatory funnels of thin glass, with short stems and small stoppers, either decanting the hot solution or drawing off the hot oil, according to conditions. Fifteen hundred grams of oil may be treated in four 1-liter funnels, each nearly filled with oil and solvent. The same cooling temperature must be maintained in all separations, and the solvent saturated with the oil from one separation may be used successively in others without distilling. The proportions of ether and alcohol must be constantly adjusted on account of the loss of ether and the different degrees of solubility of the constituents of the oil. Since separation by a solvent was first begun five years ago, i t has been observed that in extractions from heavy to light specific gravities the upper two or three fractions were much higher in specific gravity but lower in molecular weight than those below, even to the lower end. As mentioned in the other paper, these fractions were proved to contain carboxylic ethers which were thought to be the cause of the irregularities, but more extended study with other oils has shown that ethers are not the principal cause, but rather the presence in all crude oils of hydrocarbons that are more soluble than the principal constituents. One of the most marked examples is seen in the fractions of the Gulf Coast oil. After washing up several times No. 1, H, had the specific gravity 0.9834; normal, 0.9622; and No. 1, D, 0.9680. The heavier fraction had a molecular weight of 395 and an analysis of C, 89.23, and H, 10.77, leading to the formula C2(;H42,series CnHan-16, which is lower than the following members of this series. It had also an abnormally high refractive index, 1.5310. On combining all the members of the D series, and all the members of the H series, separately, again dividing them into fifteen groups, and then washing downward several times,
815
the more soluble, heavier hydrocarbons, which had given the trouble, remained in the solvent. For example, the distilled solvent from the Gulf Coast H fractions above 300"C . a t 30 mm. gave a residue heavier than water, specific gravity 1.012, at 20" C. and molecular weight 328, corresponding to a formula C24H40, which is lower than that of any of the other fractions. Distillation of Lubricants Although it has frequently been observed that lubricants in general will not stand vacuum distillation, some will distil without serious decomposition, although even these cannot be depended on, in long-continued fractionation, to yield undecomposed constituents, especially the portions distilling above 300" C. Moreover, the oils containing more than one series of hydrocarbons cannot be completely separated by distillation. The composition of the distilled lubricant fractions is given in Table I and of those from the crude oils in Table 11. , Fraction 1
2 3 4 5
1 2 3
Table I-Fractions of Lubricants Formula Specific gravity Series Lima, Ohio, sp. gr. 0.8986 D Series CwHsa CsiHsr 0.8890 to 0.9002 CnHzn-a CsaHss CuHso CasHsr H Series C36H6l C37Hu 0.8992,to 0.9054 CnHZn-10 c 38H66 Sterling Heavys Rosenbury, P a . , sp. gr. 0.8824 D Series CzzHio 0.8646 to 0.8766 CnHzn-r CzsHsa C3lHSS Oklahoma Lubricanl, sp. gr. 0.9160 One Series C34H80 CaaHa~ 0.9112 t o 0.9190 CnHzn-s C4sHs4 CarHsr CmHge Illinois, sp. g.r. 0.8644 D Series
i\
~
1 2 3 1 2 3 4 5
~
1 2 3
CzzHro CarHu
1 2
CzaH44 Cz sH4 s
1
2 3
0.9002 to 0.9034
CnHzn-s
Gulf Coast, sp. gr. 0.9400 CZQHIS 0.9150 t o 0.9225 CzzHla C25H42 Above 300" C., 30 mm. D Series -
CnHzo-s
0.9335 to 0.9417
CnHzn-s
1 1
1 2 3
CssH~s
1 2 3
C4IH72
Sp. gr.
1 2 3 4
0.9183
0.9155 0.9172 0.9193
2 3 4 5
0.9253 0,9259 0.9275 0.9515 0.9665
1 2 3 4 5
0.9422 0.9447 0.9466 0.9486 0.9892
1 2 3
0.9526 0.9734 0.9828
1 2
0.8410 0.8430 0.8434 0.8458
3 4
1
H Series
0.9350 t o 0.9482
CnHzn-io
Table 11-Fractions of Crude Oils Boiling above 300' C.,mm. Mol. wt. found Formula D Ohio Series Oil
Fraction
1
CnHzn-4
H Series
455 496 534 563 H Series 584 599 669 791 818 Illinois Oil D Series 427 464 497 506 576
CaaHss C3sHu CsaHss 01H74 c42H14 G4H7s C48HM CssHw CeoHiw
C34Hss
Series
CnHzn-I
t
I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
816
Table II- -Fractions of Crude Oils-Conch ded Mol. wt. found Formula Above 300' C.,30 mm. D Series
Fraction
Sp. gr.
1 2 3
0.9107 0.9117 0.9123
CnHzn-a
1 2 3 4
0.9239 0.9280 0.9427 0.9540
C n Hzn-12 CnHxn-la CnHzn-20
1 2 3 1 2 3 4 5 6 1 2 3
1 2 3
4 5 1 2 3 4 5 6
7 1 2 3 4 5 6 7
1 2 3 4 5
200-300° C.,at 30 mm. 279 293 0.8481 CziH44 326 Above 300' C.,30 mm. D Series 0.9045 468 C34Hea 481 C33HSZ 0.9051 506 CiiH66 0.9065 521 C3sHss 0.9070 549 C40H72 0.9112 561 C41H74 0.9125 H Series 0,9165 768 CjaHna 795 CsaHim 0.9252 844 (hard CsrHios 0.9476 asphalt) Emblenton Steam Cylinder 0.8840 0.8950 0.8955 0.8986 0,9012
Series
0.8450 to
0,9100 0.9102 0.9103 0.9132 0.9143 0.9185 0.9233 0.9456 0.9500 0.9507 0.9514 0.9548 0.9570 0,9590 0.9574 0.9673 0.9680 0.9710 0.9830
268
C19H30
CnHzn-4
i }
CnHzn-s
CnHzn-IS CnHzn-zo
CnHnn-s
'
271 CZOH32 282 CuH34 297 CzzH3a 312 CwHss CZKHM 354 386 C28H48 , Above 300' C.,30 mm. D Series 391 CzsH4a 444 CIZH32 479 C36H68 518 C37H62 567 C4lH70 584 CuHn 595 CPOH76 H Series
.
CnHzn-a
CnHzn-12
CnHzn-is CnHzn-za CnHZn-24 CnHzn-44
CABINCREEK LUBRICANT-From a Cabin Creek, W. Va., lubricant, specific gravity 0.8808 a t 20' C., described in the former paper, ten fractions were removed, running the oil t o dryness. It came over for the most part a t 280-300' C. and 330-340' C., 25 mm., in fractions that resembled, in specific gravity and molecular weight, those separated by solution from the crude oil. The first seven fractions were not sensibly decomposed. STERLING HEAVYLUBRICANT-A heavy lubricant, specific gravity 0.8824, made from the Rosenbury, Pa., type of crude described in the previous paper, distilled in vacuum, beginning a t 260" C. at 30 mm.. went t o dryness without appreciable decomposition to the last two of the ten fractions. Seventy-seven per cent came over at 300" C. a t 30 mm., the greater part a t 280-300" C. and with another accumulation a t 330-340' C. Fractional separation by the solvent and examination of these fractions indicate that the composition of this lubricant corresponds to the same series as the lighter members of the crude oil. EMBLENTON STEAM CYLINDERLUBRICANT-This lubricant, specific gravity 0.9019, also prepared from the Rosenbury, Pa., type of crude, was evidently refined by reducing the heavy cuts of the crude oil in order t o get the benefit of the valuable heaviest lubricant hydrocarbons, which are ordinarily lost in coking. Paraffin does not interfere in this type of commercial lubricant. I n distillation very little came over below 300' C. a t 25 mm., and the paraffin collected for the most part in the first two fractions. By extraction with the solvent the remaining paraffin collected in the upper end of the fourteen fractions. Analysis gave for all these fractions results close t o C, 86.60, and H , 13.40, required for the series CnHzn-8. The five principal hydrocarbons given in Table I1 show a close resemblance in composition t o those in the H series of the Rosenbury crude. WYOMING OIL-Several specimens were examined in this laboratory twenty-five years ago, in the early days of prospecting the Wyoming field. Some were heavier than water, and there was no
VOl. 18, No. 8
indication of the future output of light paraffin crudes, which are now produced in such abundance. The composition of a present representative sample from this field, the "Teapot Dome" oil, which has recently become so widely known by name, is given here. I n the large proportion of light and heavy paraffin hydrocarbons and in its low specific gravity, 0.8340 a t 20" C., this oil resembles the Appalachian oils of the East perhaps more closely than any other in western territory. However, like all western oils, it contains a small proportion of the asphaltic hydrocarbons and is low in sulfur. This sample began to distil below 30' C., and the 9 per cent coming over below 100' C. was composed of the pentanes, heptanes, octanes, besides the cyclic hydrocarbons, as shown by the temperatures of distillation halting a t the boiling points of these constituents as in the Appalachian oils. I n the 25.5 per cent coming over between 100" and 200" C. the presence of the octanes, the xylenes, nonane, and the decanes was also evident, but no further attempts were made t o identify them, since they were long ago thoroughly investigated by Pelouze and Cahours, Schorlemmer, Warren, and Mabery. The last portions of the 24 per cent distilling between 200' and 300" C. became solid with paraffin; likewise the next distillate 300400' C. a t 30 mm. After thorough pressing out of the oil and several crystallizations from ether and alcohol, the hard solid melted a t 66' C., with specific gravity 0.87 a t 20' C. Its molecular weight in stearic acid, 504, corresponds to the formula C38H,a, which was supported by the analysis C, 85.34, H, 14.47; required, C, 85.38, H, 14.62. This is the largest formula of any petroleum paraffin hydrocarbon yet identified. A determination of sulfur in the crude oil gave 0.18 per cent and in the residue above 300" C. a t 30 mm., 0.47 per cent. The distillate a t 200-300" "(2.and 30 mm., further fractionated by distillation within 10 C., was separated by the solvent into fractions that gave values by molecular weight and analysis required for the series CnHZn-zrcorresponding to the light lubricants of Pennsylvania petroleum, and t o the individual hydrocarbons CIS, CIS, CZO,and CZI,with specific gravity between 0.8534 and 0.8565. The residue was carried through a separation by the solvent, with results shown in Table 11. Lubricants are not at present made from this crude oil. ILLINOIS PETROLEUM AND LUBRICANT-The crude oil from the Illinois field, specific gravity 0.8644 at 20" C., began t o come over at 85" C. a t atmospheric pressure; below 300" C. at 30 mm., 60 per cent distilled, specific gravity 0.8360, and the residue above 300' C. had the specific gravity 0.9410. I n distillation under 25 mm. the lubricant began a t 250" C., the greater part collecting at 260-270" C., 290-300' C., and 310-320" C. It went to dryness without apparent decomposition, except the last of the ten fractions. These distillates, further separated by the solvent, gave fractions of the series C,Hgn-4 and CnHzn-8, as shown in Table I. This lubricant was evidently prepared from the lighter distillates, without including any of the heavier asphaltic constituents of which the crude oil consists to a considerable extent, as shown by the composition of the asphaltic residue extracted by the solvent. The influence of the heaviest asphaltic constituents on the specific gravity of the lighter hydrocarbons is evident in all the crude oils with a "mixed base," paraffin and asphaltic, as shown by the portion distilling above 300" C., unless they are carefully kept apart as is done in refining these oils. The portions with specific gravity below 0.9000 and those above 0.9500 show the wide differences in the composition of these constituents. OHIO PETROLEUM AND LUBRICANT-The Trenton limestone crude oil from the Lima field, specific gravity 0.8390, distilled 75 per cent below 300' C. a t 30 mm.; specific gravity of the distillate at 20" C., 0.8798, and of the residue, 0.9118. The lubricant, specific gravity 0.8986 a t 20' C., beginning at 275' C., distilled 72.5 per cent below 300" C. at 30 mm.; specific gravity of the distillate, 0.8763, and of the residue, 0.9018. Separated by the solvent into fifteen fractions, the D's of the lubricant gave values, by molecular weight and analysis for the hydrocarbons, of the series CnHzn-s and the H's for the series CnH2,-1o (Table I). The residue of the crude oil was separated by the solvent into twelve fractions, which, as shown in Table 11, proved t o be composed largely of lubricant hydrocarbons of the same series as the lubricant, and contained a smaller proportion of asphaltic hydrocarbons than has appeared in other oils with a mixed paraffin and asphaltic base. OKLAHOMA CRUDEOIL AND LuBRIcANT-In specific gravity and general composition this crude oil resembles the Wyoming oil except that it contains less of the lighter paraffin hydrocarbons and solid paraffin and less of the heavy asphaltic lower ends, but much larger amounts of the lubricant hydrocarbons. The crude oil, specific gravity 0.8461 a t 20' C., distilled to the extent of 38 per cent below 200' C., 26 per cent a t 200-300' C., and somewhat larger amounts below 300" C. a t 30 mm. than the Wyoming oil, and 36 per cent above 300' C. at 30 mm. From
INDUSTRIAL AND ENGINEERING CHEMISTRY
August, 1926
a distillate 300-340' C. a t 30 mm. less solid with paraffin than the similar distillate from the Wyoming oil, the solid obtained by pressing out the oil and crystallizing from ether and alcohol, specific gravity 0.8428 a t 20' C., and melting point 55' C. was shown by i t s molecular weight, 366, which is somewhat lower than that of the Wyoming paraffin, and analysis, C, 85.35, H, 14.65, t o be the hydrocarbon C~eHst. Neither the crude oil nor the lubricant would distil much above 300' C. at 30 mm. without some decomposition. Determinations of sulfur by combustion of the crude oil gave 0.19 per cent and in the residue above 300" C. at 30 mm., 0.59 per cent. The lubricant, distilled only t o the extent of 7 per cent below 300' C. a t 30 mm., separated by the solvent into constituent fractions as shown in Table I. These fractions indicate that this oil is composed of the best lubricant hydrocarbons, chiefly of one series. The residue of the crude oil above 300" C. at 30 mm. was also separated into fifteen fractions, H and D, and a small portion of a hard, rather insoluble asphaltic residue, of the series C,Hz,- 20, which appear in Table 11. GULF COAST OIL AND LUBRICANT-The coastal crude oil, specific gravity 0.9318 at 20' C., began t o distil a t 140' C., 30 mm., 25 per cent coming over below 200' C., 33 per cent a t 200-300' C., and 14 per cent a t 300-340' C., specific gravity of the residue at 300' C., 30 mm., 0.9605. The lubricant distilled 75 per cent below 300" C. at 30 mm. Fractionated under 25 mm., i t distilled to dryness without decomposition, except the last of the 10 fractions, as shown by molecular weight and specific gravity. I n this respect it differs from other Texas lubricants examined here, and its composition indicates that the heavy asphaltic hydrocarbons have been excluded in its preparation. In distillation, much the larger part of its constituents collected at 260-270' C. and 320-330" C., nearly one-half at 260-265' C., 25 mm. Further separation of the distillates by the solvent and examination by molecular weight and analysis showed that they were all of the series C,H2,-8, the best lubricants in any petroleum. The slight variation in specific gravity of the 10 fractions, 0.9386 t o 0.9445, indicated a small number of hydrocarbons, which was coniirmed by molecular weight and analysisCzoHsz,CzzHsa, and C Z ~ H The ~ . distillates from the crude oil and the residue were carried through several separations by the solvent, which gave fractions corresponding t o individual hydrocarbons, as shown in Table 11. It is interesting t o note that the larger part of the best lubricant hydrocarbons in the Texas Coastal oil distil below 300' C., at 30 mm., and in the Oklahoma oil above this temperature.
A summary of these results appears in Table I. Table 11shows a fairly close agreement in the data excepting specific gravity, on which the formulas of the hydrocarbons are based. The widest variations are between the Pennsylvania lubricant and the others (Table I). These differences are fundamental and cannot be explained altogether by the difference in series. There must be a difference in structure of the hydrocarbons. I n all crude oils composed of both lubricant and asphaltic hydrocarbons, and especially in those containing the larger proportion of the latter, such as the Texas and California crudes, there is a tendency toward higher specific gravity than in the Appalachian varieties. Even in the common series, CnH2n--8,this variation in specific gravity is apparent. The cause of a difference in structure is not known; i t is doubtless due to the different original sources and conditions in the formation of the crude oils. of L u b r i c a n t S e c t i o n of P e t r o l e u m f r o m Different Fields -AVERAGE PER CENTLubricants Crude oils C H C H Source Kind of oil5 Cabin Creek, W. Va. Residue, above.300' C. 86.50 13.50 86.50 13.50 Rosenbury, Pa. Residue, above 300' C. 86.65 13.35 Sterling heavy motor Lubricant 86.50 13.50 Emblenton steam 86.60 13.40 86.58 13.42 cylinder 8 7 . 4 2 12.58 Lima, Ohio 300' C. 87.83 12.17 87.62 12.38 Lubricant 8 7 . 4 0 12.60 Illinois Residue above 300' C . 89.42 10.58 88.41 11.59 Lubricaht above 300' C. 8 7 . 4 9 1 2 . 5 1 Oklahoma Lubricant'below 300' C. 8 6 . 8 9 1 3 . 0 1 8 7 . 2 4 1 2 . 7 6 8 7 . 5 0 12.50 8 7 . 3 7 1 2 . 6 3 Residue Lbove 300' C . Lubricaht below 300' C 8 7 . 8 8 12.14 Lubricant'above 300' C: 8 8 . 0 0 1 2 . 0 0 8 7 . 9 4 12 06 Gulf Coast Residue above 300' C. 8 8 . 1 0 1 1 . 8 0 8 8 . 0 7 11 93 87.05 12.95 87.05 12.95 Residue:above 300' C. Mecca Ohio Sour LLke, Texas Residue,above 300' C. 87.77 12.23 87.77 12.23 Residue,above 3OOOC. 8 7 . 5 0 1 2 . 5 0 87.50 12.50 Baku, Russia a Pressure in all cases 30 mm. T a b l e 111-Composition
1
817
Corresponding variations are observed in the proportions of carbon and hydrogen in fractions from crude oils and lubricants from different fields, as is shown by the average analyses. The percentages of carbon and hydrogen presented in Table I11are averages of all the analyses of oils described in the previous and present papers, and since the lubricants are oils that distil largely below 300' C. a t 30 mm., their proportions of carbon and hydrogen, together with those that do not distil a t this temperature, should present a fair average of the range in composition of the lubricant section of the crude oils, and thus exhibit the differences in composition of the crudes from the various oil territories. Refractive Index
On account of their opacity i t was impossible to ascertain the index of refraction of some of these oils. Yet the marked variations of the oils from different sources and their constituents, as they appear in the tables, indicate that the refractive indices may be useful in classifying the oils. Noticeable differences appear between the D and H fractions, as was observed in the previous paper-such, for instance, as the higher values in all the D fractions and especially in those of the Gulf Coast oil distilling below 300" C. a t 30 mm. and the higher D fractions of the Illinois lubricant. I n the Wyoming distillate, 300" C. a t 30 mm., there is a marked difference in the few possible observations, indicating that a considerable proportion of asphaltic hydrocarbons remained behind in the distillation. These refractive indices are given in Table IV.
Fraction
T a b l e IV-Refractive Indices of Oils Wyoming Crude Ohio Lubricant Below 300° C. Above 300' C. Solvent Fractions D H D Fraction D H
Oklahoma Crude Below 300" C. Illinois Lubricant Solvent Fractions Above 300' C., 30 mm.; Solvent Fractions Fraction D H Fraction D H Lubricant Distilled 1 1.4782 1.4771 1 1.5078 1.5010 250-260O C. 1.4990 2 1.4742 1.4740 2 1.5060 1.5000 280-290' C. 1.5070 3 1.4735 1.4730 3 1.5040 1.4995 310-320"C. 1.5030 4 1.4732 1.4729 4 1.5035 1.4990 5 1.4725 1.4719 5 i.5030 1.4985 6 1.4718 1.4713 6 1.5024 1.4982 Gulf Coast Above 300' C . ; Below 300' C . ; 30 mm. Solvent Fractions Lubricant Fractions Fraction D H D H 1 1.4940 1.4945 1.5150 1,5080 2 1.4960 1.4865 1.5150 1,5085 3 1.4979 1.4868 1.5168 1.5080 4 1.4975 1.4975 1.5160 1.5072 5 1.4975 1.4975 1.5070 1,5048 1.4977 6
A superior quality of the lubricants seems to be evident from the higher refractive indices, especially in the Gulf Coast lubricant, in which the indices of the fractions from the residue of distillation are much lower than those from the lubricant. This indicates that the asphaltic hydrocarbons in the crude oil are kept back in the process of refining, but that a t the same time the lubricant contains a large proportion of lubricant hydrocarbons that distil below 300" C. a t 30 mm., as appears in the indices of H and D fractions that are higher than those of any other oil examined in this work. The refractive index may thus be useful in ascertaining the comparative value of lubricants from different sources. It will also be observed that the indices of the H and D fractions from the Ohio lubricant are the same, which doubtless follows from the very small proportion of asphaltic hydrocarbons in the crude oil.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
818
Viscosity of Solvent Fractions
Table V-Comparison
Vol. 18, No. 8 of Specific Gravity a n d Viscosity
Specific Gravity D 0.8816 0.9058 0.9643 0.9288
at 20' C.
Viscosity
Oil Series H D H As the most important property of petroleum lubricants Rosenbury, Pa. 0.8850 78 496 Mecca, Ohio 0.8998 17 143 is viscosity, so must it also be of their constituents. While Sour Lake Texas 0.9714 1587 517 it cannot be assumed that the limited fractionation by solBaku, Ru&a 0.9360 2005 669 vents in restricted laboratory operation gives more than an approximate separation, the combined data-specific Table VI-Viscosities of Hydrocarbon Fractions i n Previous Papers gravity, molecular weight, analysis, and viscosity-indicate Russian Cabin Creek Rosenbury Mecca aq approximation to definite composition. I n %p" fractionaSour Lake (at 50' C . ) Fraction D H D H D H D H D tiQq, the last fractions after being extracted thirty times or 54 117 66 100 30 17 m 6 e , must be very close in composition to definite individ68 132 78 204 38 33 132 141 43 175 78 260 145 44 100 174 48 100 uals. 86 256 108 496 55 123 3 10 54 158 277 98 1088 65 153 316 387 90 Of the different series of hydrocarbons that make up the 354 1754 1222 101 196 385 443 2005 403 2492 2161 142 3933 1657 composition of petroleum lubricants, the paraffin hydrocar517 (at 56( C.) 808 5248 5461 594 bons of the series CnH2,+2 were shown by Mabery and (at 56' C.; tube 2 4 'Mathews to have very little lubricant quality. The next SGOLiZS) series, CnHZn, the naphthenes, credited by Russian chemists with giving lubricant quality in Russian petroleum and also Table VII-Viscosities in Present Paper considered as lubricant constituents of American oils do Water standard of tube, 1.35 seconds; temperature, 38O C. not appear in any of the oils examined in this laboratory. Lubricant Fraction The hydrocarbons of this series seem to disappear in the sepaGulf Coast Ohio Illinois Oklahoma H D H D H D H ration of the lighter portions of the crude oils. The first series Fraction D 1 107 88 with lubricant quality in American petroleum is CnHzn--2, 2 121 98 42 43 35 43 32 45 3 105 96 49 54 38 44 39 47 which forms a large part of the light lubricants in Appalachian , 4 106 100 50 55 43 44 45 63 oils and is also a constituent of most of the lighter crudes in 5 113 105 51 57 43 45 57 101 6 54 60 45 45 80 120 other territory. Of the heavier series, the one most fre7 80 88 45 46 ~. S 115 140 45 46 quently present in light and medium heavy crudes is CnH2n-4. But the general lubricants, especially of the heavier grades, Crude Oil Fractions (at 300' C.,30 mm.) are the hydrocarbons of the series CnHzn--8. They represent Wyoming Gulf Coast (at 70' C . ) the heavy lubricant constituents of all Appalachian oil, Fraction D H D H and are the principal representatives of lubricant quality in 1 79 80 32 45 2 86 90 35 46 the Midcontinent fields. The superior grade of lubricants 3 106 99 39 50 4 145 113 41 63 refined from Oklahoma and Coastal crudes is due to the large 5 257 142 43 101 proportion of the hydrocarbons of this series, as shown in 6 57 120 7 80 Tables I and 11. Hydrocarbons of the next series, CnH~n-l~, CnH2n-12, CnHzn-14, CnHZn-16, and CnHZn-38 also possess lubricant quality, but in diminishing ratio approach the Comparative Strength of Lubricant Molecules asphaltic end, which is shown in the tables to begin a t about the series C,H2.-m. I n these series, therefore, the complete The two properties that determine the efficiency of lubrirange of lubrication by petroleum hydrocarbons has been cants are viscosity, which measures the strength of molecular presented, and it appears that the quality of any lubricant cohesion, and the inherent resistance of the individual moledepends on the composition of the crude oil that provides cules to rupture under stress. By the influence of cohesion, the hydrocarbons; from a crude oil inferior in its composition oil films may withstand the breaking force of heavy loads, even when reduced to the thickness of single molecules, a superior grade of lubricant cannot be made. On account of the limited supply of the samples, the viscosity but the resistance to rupture and consequent break of any determinations were made in Ostwald tubes (water standard of oil lubricant depends on the ultimate structure of the oil the tube in common use, 2.8 seconds at 38" (3.). With some molecules which have been shown in these papers to be widely fractions of the heavy Midcontinent lubricants observations variable, and i t must stand in close relation to the durability had to be made at 70" C. It is common knowledge in the of the lubricant under any stress. Several years ago Ubbelohde published the statement that lubricant industry that oils of the same viscosity from different fields may show a large variation in specific gravity as much, the lubricant value of petroleum lubricants of the same visfor example, as 0.8800,0.9000, and 0.9200. Much wider differ- cosity is the same irrespective of their origin, methods of ences appear in the constituents of oils from the same field refining, or other physical constants. This statement is as shown in Table VI, A marked variation in viscosity ap- based on the assumption that the molecules of all lubricants pears in the solvent fractions of series D and H described in have the same stability; that the best lubricants made, for example, those from Pennsylvania, Oklahoma, or Coastal crudes, both papers as shown in Tables VI and VII. ~~
1
Oil Standard oil Cabin Creek, W. Va. Rosenbury, Pa.
Fraction 6-D
I E I t:::
Sour Lake, Texas
{ 6-D 6-H { E:
Baku, Russia
I 65:
Mecca, Ohio
Table VIII-Lubricating Qualities of Oils Flow of oil, 8 drops per minute; speed, 660 r. p. m. Temp., O C. r Friction Coefficient 0.3000 0.4000 0.0044 0.0044 80 to BO 0.0049 0.0048 0.0050 85 to 92 0.0051 0.0048 0.0048 0.0047 0.0049 85 to 90 0.0044 0.0044 0.0045 88 to 93 0.0052 0.0050 0.0048 0.0048 0.0048 87 t o 89 0.0045 0.0048 77 to 86 0.0048 . 0.0047 0.0044 0.0044 0.0044 77 to 83 0.0044 78 to 81 0.0044 0.0044 0.0045 0.0047 78 t o 88 84 to 97 0.0050 0.0061 87 to 97 0.0008 0.0089
Smoke
Break
5000 4500 4500 4500
5000 5500 5500 0000 5500 5500 5000 5000 4500 4506
Series CnHln-s CnHtnd CnHm-11 CnHtn-s CnHm-u C n H t n- II CnHan-is CnHtn-ir CnHrn-1s CnHzn-i o CnHzn-r
INDUSTRIAL A N D ENGINEERING CHEMISTRY
August, 1926
have the same resistance to breaking stress as lubricants made from California oil or other highly asphaltic base oils. It therefore seemed worth while to examine some of the oils described in these papers as to their behavior in lubrication. The observations in Table VI11 were made on a hard babbitt bearing, twelve years in use in this work, kept a t an exact standard by an oil with frictional coefficient 0.0044, temperature 80-90' C., under 3000 to 6000 pounds pressure, no smoke and no break a t 6000 pounds. No lubricant should show smoke under 5000 pounds and should not break under 5500 pounds. Under these conditions, and with suitable regulation of speed, the results of such oil tests are as reliable as any other tests controlled by a proper standard.
819
Acknowledgment
The writer desires to express his obligations to the Texas Company, the Sinclair Refining Company, the National Refining Company, the Indian Oil Company, the Ohio Valley Oil Company, the Fred G. Clark Company, the Pure Oil Company, the Sterling Oil Company, the Sun Oil Company, and especially to Orton C. Dunn of Smith & Dunn, Marietta, Ohio, for generous supplies of crude oils and lubricants, to W. H. Parish, and to K. G. Mackenzie of the Texas Company for valuable suggestionsin the progress of this work, and to his assistants, N. Marmelstein and A. S. Gressel, for efficient aid.
The Determination of Biguanide' By C. D. Garby FIXEDNITROGEN RESEARCH LABORATORY, WASHINGTON, D. C.
IGUANIDE is one of the numerous compounds that can be indirectly derived from cyanamide. A great many of its derivatives have been prepared, but little attention has been given to a quantitative method for its determination. It has usually been estimated as the copper salt precipitation from an alkaline solution, but no specific directions have been given for this determination. I n order to distinguish between biguanide and closely related compounds, the method described herein has been developed in this laboratory. A few of the properties of biguanide compounds that are of interest in this determination will be mentioned. Biguanide salts, such as the nitrates or hydrochlorides, form precipitates with copper or nickel salts when the solutions are made alkaline with ammonium hydroxide in the presence of mannite. Two distinct forms of crystals are produced, such as nickel biguanide nitrate, Ni(C2NaH&. 2HN03 (needles), and nibkel biguanide hydrate, Ni(C2N&H&.2Hz0 (plates). The nitrate is precipitated in slightly alkaline solutions, while the hydrate is precipitated in strongly alkaline solutions. This compound has many of the properties desirable for the determination of biguanide by a gravimetric method. It is insoluble in alkaline solutions, comparatively stable a t 120-125' C., has a fairly large molecular weight, and is readily filtered from the mother liquor. The method as given ii a modification of that used for the determination of dicyanodiamide as nickel guanylurea.* The conditions given for the precipitation of nickel guanylurea hydrate are conditions which will also quantitatively precipitate nickel biguanide hydrate. The problem therefore resolved itself into finding the conditions under which biguanide salts would precipitate with nickel while the salts of guanylurea would remain in solution. Advantage was taken of the solubility of nickel guanylurea in strongly ammoniacal solutions; the control of the alkalinity by means of a suitable indicator; and the time required for the precipitation of nickel guanylurea hydrate when these conditions were strictly adhered to.
B
Reagents
The reagents required for the nickel biguanide determination are as follows: (1)0.12 per cent ammonia water (5 cc. concentrated NH40H per liter) ; (2) mannite; (3) diammonium hydrogen phosphate; 1 2
Received June 8, 1926. THIS JOURNAL,17, 266 (1925).
(4)nickel reagent (40 grams NiNOa. 6H20, 100 cc. 10 per cent mannite, water solution, 40 cc. concentrated N&OH, 15 cc. 25 per cent KOH); (5) 25 per cent potassium hydroxide; (6) concentrated ammonium hydroxide; (7) trinitrobenzene, saturated alcoholic solutions. Procedure ( a ) I n absence of guunylurea. Make up a sample of convenient size, containing approximately 0.1 gram of biguanide salt, to a volume of 25 to 30 cc. in a large-mouthed, glassstoppered weighing bottle or other suitable glass-stoppered container. To this solution add sufficient mannite to make an approximately 10 per cent solution, 10 cc. of concentrated ammonia, 5 drops of trinitrobenzene, and drop by drop sufficient 25 per cent potassium hydroxide to produce a color change from dark red to yellowish red. (An excess of KOH in the absence of guanylurea produces no bad results.) Then add from 0.5 to 3 cc. of nickel reagent, depending upon the amount of biguanide present. Allow the stoppered samples to stand for from 2 to 3 hours and filter through a weighed Gooch crucible. Wash with 100 cc. of solution (1). Dry at 125' C. for 1 hour to remove water of crystallization. Weigh as nickel biguanide Ni(C2N5H&. (6) I n presence of guanylurea. Make the sample up to 30 cc. as directed in (a). Add sufficient mannite to make a 10 per cent solution (2.5 grams), 0.2 gram diammonium hydrogen phosphate; 0.1 gram ammonium nitrate, provided no ammonium salts are in the sample, 10 cc. of concentrated ammonium hydroxide, 5 drops indicator, and drop by drop sufficient 25 per cent potassium hydroxide to produce a color change from cherry-red to reddish yellow. Add from 0.5 to 3 cc. of nickel reagent, allow to stand for 3 hours and proceed as in ( a ) . Results The results by this method in the presence of guanylurea salts are shown in the accompanying table. Biguanide nitrate Gram 0.2000 0.1000 0.0500 0.0100 0.0100 0.0100
3
Precipitate Gram 0.1582 0.0790 0.0394 0.0078 0.0078 0.0079
Recovery Per cent 100.3 100.2 100.0 99.0 99.0 100.0
The results are very satisfactory. I n every case the weight of the precipitate is within a fraction of a milligram of the theoretical results.
