PETROLEUM-SHALE OIL mineral carbon dioxide at this temperature to form hydrogen and carbon monoxide. Aromatic content of the neutral naphtha fraction of the oil increased with increase in temperature, reaching a maximum of almost 1 0 0 ~ for o the 1700' F. oil. The highest benzene yields were obtained in the temperature range 1500" t o 1700" F. and amounted t o as much as 5 gallons from each ton of 50-gallonper-ton shale. ACKNOWLEDGMENT
This project was part of the Synthetic Liquid Fuels Program of the Bureau of Mines and was performed a t the Petroleum and Oil-Shale Experiment Station under the general direction of H. P. Rue and H. M. Thorne. Special thanks are due various members of the personnel of the station for their valuable assistance in carrying out this project. The work was done under a cooperative agreement between the University of Wyoming and the U. S. Department of the Interior, Bureau of Mines.
LITERATURE CITED (1) Aries, R. S., and Copulsky, W., Oil Gas J., 49, NO. 9, 54-6 (July 6, 1950). (2) Chem. Eng. News, 28,3866-70 (1950). (3) Dinneen, G. U., Ball, J. S., and Thorne, H. M., IND.ENG.CHEM., 44, 2632 (1952). (4) Dinneen, G. U., Smith, J. R., and Bailey, C. W., Ibid., 44, 2647 f1952). (5) Hibbard, A. B., and Robinson, W. E., U. S. Bur. Mines, R e p t . Invest. 4744 (1950). ( 6 ) Lewes, V. B., Brit. Patent 9988 (Nov. 20, 1913). (7) . . Stanfield, K. E., and Frost, I. C., U. S. Bur. Mines, Rept. I n u e s t . 4477 (1949). (8) Thorne, H. M., Murphy, W. I. R., Stanfield, K. E., Ball, J. S., and Horne, J. W., paper presented a t Second Oil Shale and Cannel Coal Conference, Glasgow, Scotland, July 1950. (9) Yeadon, J. R., Brit. Patent 114,971 (Jan. 25, 1918), RECEIVED for review January 22, 1952. ACCEPTED May 19, 1952. Presented a t the XIIth International Congress of Pure and Applied Chemistry, New York, September 1951.
(High Temperature Shale Oil)
PRODUCT COMPOSITION G . U. DINNEEN, J. R. SMITH, AND C. W. BAILEY Petroleum and Oil-Shale Experiment Station, Bureau of Mines, Laramie, Wyo.
C
R U D E shale oil is obtained by retorting the solid organic material occurring in oil shale. The purpose of the present investigation was t o determine the composition of oils produced by retorting a t temperatures substantially higher than those normally employed ( 3 ) . Detailed analysis of the products presented a complex problem, as shale oils usually contain saturated, olefinic, and aromatic hydrocarbons, plus significant amounts of nitrogen- , sulfur- , and oxygen-containing compounds. Therefore, simple physical property correlations do not give satisfactory results. T o obtain an adequate picture of the composition of shale-oil distillates, a number of techniques including fractional distillation, adsorption, and spectrometry are used. PRELIMINARY TREATMENT OF SAMPLES
The three samples studied in the present investigation were produced as described in (.2) at temperatures of 1200', 1500°, and 1700' F., and the oils are designated by these temperatures. The quantities available for analysis amounted t o about 2.5 liters for the 1200' F. oil, 2 liters for the 1500' F. oil, and 0.8 liter for the 1700' F. oil. Because of the differences in sample size, the scheme of analysis used on the 1700' F. oil differed somewhat from t h a t used for the other two. A schematic presentation of the work done on the 1200" and 1500' F. oils is shown in Figure 1. The 1700' F. oil was fractionated directly in a manner similar to t h a t used for the neutral oils from the 1200' and 1500' F. oils, The separation into four wide-boiling cuts (see Figure 1) was made t o permit more efficient extraction of the t a r acids and tar bases. Also, by making a number of analytical fractionations, the time during which a given sample was maintained at elevated temperature was minimized. The four wide-boiling cuts were prepared using a 5-liter flask equipped with a Claissen head packed to a depth of several inches with glass beads. T o minimize cracking, fractions 2 and 3 were distilled a t pressures of 40 and 1 mm. of mercury, respectively. As shown-in Table I, the oils have roughly the same boiling-range distribution, but their chemical compositions are quite different, as indicated by the densities and viscosities. The sulfur contents of the two oils and of the fractions
November 1952
from them show only minor differences. The nitrogen may be separated into two classes. Basic nitrogen is present in compounds, principally pyridines and quinolines, that may be titrated by perchloric acid in a glacial acetic acid solution ('7); nonbasic nitrogen is present in compounds, principally pyrroles, not titratable by the above reagent. As shodn in Table I, the distribution of the two classes of nitrogen with respect t o boiling range is very different. The sediment values shown in the table represent the mineral and carbonaceous matter t h a t was insoluble in benzene. All results reported in this paper are on the basis of the crude shale oils as analyzed without correction for this sediment. Each of the first two fractions was extracted with 10% aqueous sodium hydroxide t o remove acidic materials and then with 10% aqueous sulfuric acid to remove basic constituents. The raffinate oil was neutralized with dilute caustic and washed with distilled water. The t a r acids and tar bases were liberated from the aqueous extracts, recovered, and reserved for analysis. The yields of tar acids and tar bases and some properties of the neutral oils are shown in Table 11. The fractions from the 1500' F. oil are more aromatic than those from the 1200' F. oil. The sulfur contents of the neutral oils from the second fractions are higher than those of the raw fractions because of the removal of large quantities of tar bases t h a t are low in sulfur. The nitrogen results in Table I1 show that the dilute acid extraction was effective in removing the basic nitrogen from the first fractions but not from the second fractions. It has been found previously t h a t effectiveness of extraction decreases in higher boiling materials. The nitrogen results in Tables I and I1 are not directly comparable as the former are on the raw fractions, whereas t h e latter are on the neutral distillates. However, the generally lower nonbasic nitrogen values in Table I1 show t h a t some of this type of nitrogen compounds was removed by acid extraction. COMPOSITION OF NEUTRAL DISTILLATES
Distillation. The neutral oils from the wide-boiling fractions were subjected t o an analytical fractionation, as indicated in Figure 1, to improve the results obtainable by adsorption and spectrometry. T h e distillation of the material boiling up to
INDUSTRIAL A N D ENGINEERING CHEMISTRY
2647
Table I.
Properties of Wide-Boiling Fractions Obtained from 1200" and 1500" F. Crude Shale Oils Wt. % of Crude
Description of Sample
Vol. % of Crude
Density at 20° C.
__Viscosity, Cs. 100°F.
210'F.
Sulfur,
70
-
Nitrogen, % Basic Eonbasic,
Sediment,
%
Ash, %
1200' F. OIL lrac Frac: Frac. Frac.
1 u p t o 150' C. 2: 150" t o 280' C. 3 280' t o 540' C.
17.1 20 3 14.1 37.3
4: residuum
2 1
32 5
1 0972
1500' 8'rac. 1, u p t o 150" C . Frac. 2 , 150' t o 280' C. Frac. 3, 280'to 540' C. Frac. 4 , residuum
26.2 19.2 17.5 37.0
31 20 17 31.3
1.2568
Cmde Shsla Oil
I
Distillation
150' to 280' c.
up to SO' C.
280' to
5h0. c.
I Fvoperties
Reaiduus
I
FTopertiec
Treatment rith aqueous NaOH
TPI w i d 0
Analytical Fractionnt1on
I
moperties
Figure 1.
F.OIL
Outline of Work Done on 1200' and 1500' F. Shale Oil
plugging the take-off system. Fraction 2 from the 1500" F. oil was distilled in a spinning-band column (6 x 600 mm.). The small diameter tubes in this column plug easily, so most of the naphthalene in the sample was removed before distillation. The sample mas dissolved in about four times its volume of pentane, cooled t o minus 40" C., and filtered. The remaining oil was distilled a t three successively reduced pressures as follows: About 30% distillate vias collected at 300 mm., 20% a t 100 mm., and 20% a t 50 mm. The stepwise reduction in pressure was used in order to operate a t as high a pressure as possible while avoiding decomposition. Analysis of Fractions. Determination of individual compounds and types of compounds in the fractions often required a combination of adsorption, spectrometric, and chemical analyses. Fractions in n-hich the presence of saturates, olefins, and aromatics was suspected were analyzed for these classes of compounds by adsorption using silica gel (4, 5 ) . The saturates and olefins were classified as aliphatic or cyclic, using refractive index and boiling point ( 5 ) . The identification of individual compounds, especially aromatice, was made from a consideration of ultraviolet spectra, mass spectra, and boiling range of the fraction. Many of the fractions from the two higher temperature oils were composed almost entirely of aromatics, so on these spectra and boiling range only were used. The methods as applied are best explained by illustrations. Adsorptograms of fractions 28 and 29 from the distillation of the 1200' F. oil are shown in Figure 2, These fractions have boiling ranges of 111" to 119" C. and 119' to 126' C., respectively. The three plateaus in the curve for fraction 28 are due t o saturates, olefins, and aromatics, plus sulfur and nitrogen compounds. As may be seen from the curves, the
150" C. was made at an atmospheric pressure of about 585 mm. of mercury. The material boiling between 150" and 280" C. was distilled at reduced pressure t o prevent possible decomposition. T h e atmospheric distillations of the first fractions from the two lower temperature oils and of the total 1700' F. oil were made in a vacuum-jacketed, heligrid-packed column having a 5-foot packed section. Fractions from these distillations contained about 10 ml. as this was the minimum quantity necessary for the desired analytical determinations. Two types of columns were used for distillation of the material boiling between 150" Table 11. Yields of Tar Acids, Tar Bases, and Neutral Oil from First Two Fractions of and 280" C. The 1200" and 1200" and 1500" F. Crude Shale Oils and Some Properties of the Neutral Oils 1700" F. oils were distilled in hr0a 1-inch column containing a matics plus 6-foot Stedman-screen packS and i*; Coming. The distillation of fracBatu- Olefins, pounds, 1'01. Vol. Sulfur ' tion 2 from the 1200" F. oil 7~ of % of TV~. Nitrogen. Wt. % rates, ~ o l . VOL Description of Sample Fraction Crude 70 Basic Eonbasic Vol. % % % was conducted a t 40 mm. Frac. 1 from 1200° F. oil pressure so the pot tempera.. .. .. 0.5 0.2 .. .. .. T a r acids .. 2.6 0.8 .. .. ture remained below 250" C. T a r bases 46 Neutral oil 96.9 31.5 O.'7l 0:0 o:is 19 3.5 The residue from the atmosFrac. 2 from 1200° F. oil pheric d i s t i l l a t i o n o f t h e .. .. .. .. Tar acids 3.5 0.7 .. .. 17.0 3.6 .. T a r bases 1700" F. oil was distilled a t Neutral oil 79.5 16.7 0:95 0:OS 0:74 '8 23 ks zi pressure of about 25 mm. Frac. 1 from 1500' E". oil .. .. .. .. .. .. of m e r c u r y . T h i s l a t t e r 1.6 0.5 .. T a r acids .. 1.7 Tar bases 5.3 sample contained consider'i 4 98 Neutral oil 93 1 29.6 0:74 0:O 0:i7 able quantities of naphthaFrac. 2 from 1500' F. oil .. .. .. .. .. T a r acids 1.3 0.3 .. lene so that special attention .. 21.2 4 3 T a r bases 100 Neutral oil 77.5 15.8 0:87 o:i9 i:io 0 '0 was necessary to keep this material from solidifying and
2648
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 11
PETROLEUM-SHALE OIL 1.21
I
Table 111. Content of Saturates Boiling below about 280' C. i n Crude Shale Oils Produced at 1200" a n d 1500' F.a Volume % in Crude Oil Retorted at 1200° F. l i j O O o F. 0.04 0.01 0.16 0.05 0.28 0.02 0.65 0.05 0.29 0.02 0.43 . ,. 0.90 .. 0.17 .. 0.22 .. .. 0.25 0.27 .. .. 0.28
Compounds Butanes Pentanes Hexanes Heptanes Octanes Nonanes Decanes Undecanes Dodecanes Trideoanes Tetradecanes Pentadecanes Cycloparaffins C yclopentane
0.79 0.26 1.18 0.58 0.04 0.02 0.02 0.03 0.02 0.02 0.02
c5
c7
CS c 9
ClO Cll c12
Cia c 1 4
c 1 6 Q
-FRACTION 35
0.02 0.05 0.04 0.05 0.02
.. .. .. .. .. ..
Negligible quantities were obtained a t 1700' F.
plateau for saturates, which is the first one, may have either a higher or lower refractive index than the following olefin plateau, depending on the relative quantity of cycloparsffins present. The high refractive index of the saturates plateau for fraction 28 indicates that i t contains primarily cycloparafIins, and boiling-range considerations indicate that they are mainly cyclopentanes. The contents of saturates and olefins are shown in Tables I11 and IV, respectively. The last plateau on the adsorptogram is contributed to by sulfur and nitrogen compounds as well as by aromatic hydrocarbons. The quantities of the former compounds are calculated from weight per cent of sulfur and nitrogen in the fraction and subtracted from the total volume in the plateau to give the net content of aromatics. Fraction 28 contains a considerable quantity of aromatics whereas fraction 29 contains only a small quantity, if any. The aromatic compound in fraction 28 may be identified as toluene from a consideration of boiling range alone, b u t identifications in higher boiling fractions often require ultraviolet absorption data. For example, fractions 33 and 35 both
0.01 2200
I
I
2400 2600 2000 '300 WAVE LENGTH. ANGSTROM UNITS
Figure 3. Ultraviolet Absorption Curves of Fractions 33 and 35 from Distillation of 1200° F. Shale Oil
have a high aromatic content which, from boiling point considerations, could be due to xylenes. However, the ultraviolet absorption curves given in Figure 3 show that fraction 33 contaiis both m-xylene (peaks a t 2650, 2685, and 2725 A.) and p-xylene (peaks a t 2660, 2685, and 2745 A.). The curve for fraction 35 shows the absence of these compounds but the presence of styrene (peaks a t 2735,2820, and 2905 A.) and a small amount of o-xylene (peak a t 2710 A.). The presence of styrene was confirmed from a mass spectrum of the fraction. The determined content of aromatic and sulfur compounds in the oils is given in Table V. Discussion. The outstanding characteristic shown by the 1500" and 1700" F. oils is their aromaticity. As shown in Tables I11 and IV, they contain almost negligible quantities of saturates and olefins. The 1200" F. oil, although much less aromatic than
''52 Table IV. Content of Olefins Boiling below about 280" C. i n Crude Sha1e:Oils Produced a t 1200", 1500°, and 1700'F.
Y
Compounds Butenes Pentenea Hexenes Heptenes Ootenes Nonenes Deoenes Undeoenes Dodeoenes Tridecenes Tetradecenes Pentadeoenes Butadienes C yclopentadiene Cyclic olefins and diolefins CS C5
1.400
1.38010
Figure 2.
'
IO.
20
c 7 (7.
c; I
30
I
40
50
60 70 FILTRATE, VOLUME PERCENT
SO
90
I
100
Adoorptograms of Fractions 28 and 29 from Distillation of 1200" F. Shale Oil
November 1952
Volume % ' in Crude Oil Retorted a t 1200O F. 1500' F. 1700' F. 0.42 1.59 0:03 0.14 0.03 0.37 .. 0.01 1.49 0.10 .. 1.07 .. 0.03 0.67 0.32 .. .. .. 0.38 0.53 .. .. 0.63 .. .. 0.63 .. .. 0.25 .. .. .. .. 0.39
ClO C11 c12
cis Cl4
CIS
INDUSTRIAL AND ENGINEERING CHEMISTRY
.. ..
1.95 0.61 0.68 0.37 0.58 0.22 0.10 0.23 0.22 0.28 0.13
.. 0103 0.10 0.04
..
.. .. ..
..
0:01
.. .. .. .. ..
.. ..
.. .. 2649
Table V. Content of Aromatic a n d Sulfur Compounds Boiling below about 2!O0 C. i n Crude Shale Oils Produced at 1200 , 1500°, a n d 1700' F. Volume 70 Conipounds Benzene Toluene Ethylbenzene ylenes 9 Benzenes Cia Benzenes CII Benzenes C n Benzenes Higher boiling benzenes Styrene a- a n d @-Methylstyrene Clo Styrene Indene Naphthalene 1-Methylnaphthalene 2-Methylnaphthalene DiDhenvl Dheth>inaphthalenes Higher boiling naphthalenes Thiophene Ca Thiophenes c6 Thiophenes C1 Thiophenes Unidentified sulfur compounds Unidentified nitrogen compounds
Table VI.
of Crude Oil Retorted a t 1200' F. 1300° F. 1700' F 4.88 15.50 22.56 4.41 7.26 0.97 0.38 0.19 j2.11 2.15 1 0.02 1.09 0.66 0.02 0 19 0.72 0.01 0.67 0.80 0.89 0.30 1.44 0.10 ... 0.62 0.69 0.04 0.11 0.39 ...
\
0 : 80 0.47 0.33 0.42
..
1:oz 0.07 0.17 0.14 0.04 0.88 1.36
0.10 1.16
0:07 8.69 ! 0.23
3.60 0.80 1.80 0.10 1.60
...
0.16 0.22 0.08 0.03 0.74 2.41
0.14 0.02 0.01 0.01 0.19 0.59
Composition of Phenolics Extracted from 1200" a n d 1500" F. Oils
Volume 8 of Phenolics 1200° F. 1500'F. oil oil 1 35 Phenol o-Cresol 3 22 m-Cresol 3 19 o-Ethylphenol 1 2 2,3-Xylenol 3 3
Volume % of Phenolics 12003 F. 1300° 1.'. oil oil 15 11 ,. 3
2,4-Xylenol 2,Z-Xylenol 3,4-Xylenol 3,5-Xylenol Higher boiling material
2
4 66
,. ,.
5
the oilsproduced a t the higher temperatures, has about twice t h e aromatic content of oils produced by usual retorting methods (1), Also, for this oil the ratio of aliphatic to cyclic compounds is about 4 to 3 for paraffins and 3 t o 2 for olefins. These ratios are substantially lower than those usually obtained for shale oils, indicating a relatively large content of cyclics. The contents of nonaromatic compounds, particularly the cycloparaffins, decrease with increasing molecular weight. I n addition to the general high aromatic content of these oils, the content of individual aromatic hydrocarbons shows an important relationship to temperature of retorting. The contents of benzene and naphthalene increase steadily with increasing temperature. The contents of toluene and the methylnaphthalenes reach a maximum in the 1500" F. oil. The other alkylbenzenes in this boiling range are nearly absent in the 1700' F. oil and are present in only rather small amounts which do not show a definite trend in the 1200' and 1500" F. oils. Styrene and indene follow the same pattern as the alkylbenzenes. IDENTIFICATION OF TAR ACIDS
The pH of the alkaline extracts from the second fractions of the 1200' and 1500' F. oils was adjusted to about 8 in order to liberate
the phenols while maintaining the carboxylic acids in the extracts. Because of the small amount of phenols originally present in the oil, this treatment yielded only about 5 ml. of mateiial from each oil for examination. Each of the samples ivas separated by distillation into four fractions and infrared spectra were obtained on the fractions. After qualitative identifications, quantitative determinations (6) were made of the compounds boiling below about 220" C. The results are given in Table VI. Although the fractions from which the phenols were extracted had approximately the same boiling range, the great difference in the distribution of the phenols from the two oils is evident. I n the 1200" F. oil about two thirds of the material boils above the xylenol range, whereas in the 1500' F. oil phenol, o-cresol, and m-cresol make up 75% of the phenols. This is additional
2650
evidence that higher retorting t,emperatures tend t o produce the simpler members of a homologous series. IDENTIFICATION OF TAR BASES
The tar bases were liberated and recovered from the aqueous acid extracts from the 1500" F. oil. The bases were separated by distillation into narrow-boiling fractions and infrared spectra were obtained on the fractions. Lack of spectra for a sufficient number of k n o m compounds prevented quantitat,ise determinations so only the bases from the 1500° F. oil were examined. The compounds qualitatively identified were 2-rnethylpj~idine~3methylpyridine, 4-methylpyridine, 2,ldimethyIpyridine, and 2,4,6-trimethylpyridine.As in shale oils from ordinary retorting is the predominant commethods, the 2,4,6,-trimethylpyridine pound (1). The 2,4-dimethylpyridine is present in significant amounts. Several pyridine homologs, whose infrared spectra mere available, appeared to be absent. These are 2,3-dimethylpyridine, 2 6-dimethylpyridine, 3,4-dimethylpyridine, 2-met hyl4-ethylpyridine, and 2-methyl-6-ethylpyridine. ~
SUMMARY
The compositions of shale oils produced a t 1200', 1500°, and li00" F. were investigated by systematic analyses. The material in the oils boiling below 280' C. was separated into narrow-boiling fractions by distillation. The composition of each fraction was determined from a consideration of data obtained from one or more of the following determinations: silica gel adsorption analysis; infrared, ultraviolet, or mass spectrum; refractive index; density; and boiling range. All three of the oils studied in this investigation are much more aromatic than oils ordinarily produced by the usual retorting methods. The 1500' and 1700" F. oils consist essentially of aroma& hydrocarbons and sulfur and nitrogen compounds. The contents of benzene and naphthalene increase x i t h retorting temperature. The contents of toluene and the methylnaphthalenes reach a maximum in the 1500' F. oil. Phenol, o-cresol, and m-cresol are the predominant compounds in the tar acids from the 1500' F. oil. The tar bases from this oil show large relative quantities of 2,4,6-trimethylpyridine and 2,4-dimethylpyridine. ACKNOWLEDGMENT
This project was part of the Synthetic Liquid Fuels Program of the Bureau of Mines and was performed a t the Petroleum and Oil-Shale Experiment Station under the general direction of H. P. Rue and H. M. Thorne. J. S. Ball was in direct charge of the work. The authors wish t o thank C. S. Allbright,, I . W. Kinney, Shirley Nix, W. D. Anthony, G. L. Cook, R. T. Rfoore, and I. A. Jacobson for many of the analytical determinations. The TTork 11-as done under a cooperative agreement between the University of Wyoming and the U. S. Department of the Interior, Bureau of Rf ines , LITERATURE CITED (1) Ball, J. S., Dinneen, G. U., Smith, J. R., Bailey, C. W., and Tan Meter, R., I N D . ENG.CHEM.,41, 581 (1949). (2) Brantley, F. E., Cox, R. J., Sohns, H. W.,Barnet, 1%'.I., and Murphy, W. I. R., I x D . ENG.CHEM.,44, 2641 (1952). ( 3 ) Cattell, R. 9., Guthrie, Boyd, and Schramm, L. W., "Retorting Colorado Oil Shale-A Review of the Work of the Bureau of Mines, U. S. Department of the Interior," Second Oil-Shale
and Cannel Coal Conference, Glasgow, 19.50. (4) Dinneen, G. U., Bailey, C. W.,Smith, J. R., and Ball, John S., Anal. Chem., 19, 992 (1947). ( 5 ) Dinneen, G. G., Thompson, C. J., Smith, J. R., and Ball, J. S., Ibid., 22, 871 (1950). (6) Friedel, R. A . , Pierce, L., and McGovern, J. J., I b i d . , 22, 415 (1950). (7) M o o r e , R. T., McCutchan, P., and Young, D. A , , Ibid., 23, 1639 (19.51). RECEIVED for review January 2 2 , 1952. ACCEPTED M a y 19, 1962. Presented as p a r t of the Symposium on Modern Techniques in Research o n Coal a n d Related Products before the Division of Gas and Fuel Chemistry a t the Diamond Jubilee Meeting of the AMERICAX CHEXICAL SOCIETY,New York, September 1951.
END OF SYMPOSIUM
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 44, No. 11
