586
INDUSTRIAL AND ENGINEERING CHEMISTRY
v Figure 1. Apparatus
smaller, such incidents as having the equipment slightly out of vertical may have undue effect. Tube E should be marked so that no rotation between it and D need occur when making adjustments. Obviously these tubes are not truly concentric when ordinary glass tubing is used, and they are not truly straight. Any rotation should not change the cross-sectional rLrea of the
Vol. 44, No. 3
annulus but may change the shape of annulus a t some sections and thus change the flow. If a rubber band is placed around the upper portion of A and E, the lower end of the plunger is forced a t all times into contact with the wall of D remote from A and ensures identical positioning at all times, thus eliminating a possible source of inaccuracy. To make adjustments the gosition of the plunger may be measured and depressed or raised y a known amount and a calibration curve prepared. T h e control is rendered inaccurate if the annulus is made very short, say less than an inch. When a soluble gas such as chlorine is to be fed into the system with the liquid, it cannot be used for pressure equalization and a very slow feed of nitrogen can be supplied at K through a bubble bottle in sufficient quantity to bubble out from G as needed t o displace the liquid; any excess passes out through the constriction. R. I n this case it is inevitable that a t least a trace of the nitrogen enters the reactor. The stopcock L is provided t o permit calibration without dieconnecting the apparatus. To recharge A with minimum interruption t o t h e flow it is provided with certain attachments which are operated in this way: Stopcocks A l , N , and P are opened, t h e liquid is run in, A 1 is closed, the rubber bulb, Q is com ressed, P is closed, the bulb is released, drawing gas in througi G and establishing the required pressure, and N is then closed. These attachments obviously are not absolutely necessary but are advantageous. The accuracy of this instrument is mainly dependent on thorough cleanliness and good temperature control. I n some instances it is desirable to use a spiral down-flow arm on U-tube 11 to provide more complete temperature equalization. illternatively, the temperature of the liquid in funnel A can be maintained a t a fairly uniform temperature. LITERATURE CITED
(I) Nichaeli, I., Chomistrg & Induatrg, 1951, 126. RECEIVED f o r review J u n e 28, 1961.
~ C C E P T E DOctober
10, 1951
Hydrogenation of Shale Oil W. M. SMITH AND T. C. LANDRUM
G. E. PHILLIPS
Esso Laboratories, B a t o n Rouge, La.
Esso Laboratories, Elizabeth, N. J .
1J VIEW of the possible shortage of crude petroleum in the future, attention has been turned to the development of processes for the production of crude oils from other natural resources such as natural gas, coal, tar sands, and oil shale. It is with the latter raw material that this paper is concerned. The production of oil from shale is not a new concept (1, 5 , 6) but an established industry in various sections of the viorld which contain extensive oil shale deposits and are deficient in crude petroleum. In these locations, the comparatively high costs of mining, extracting, and refining shale oil do not prevent its use in competition with petroleum. I n this country, although shale oil is not now- competitive with petroleum, it may become so in the future. I n order t o provide a background of information on oil shale processing against this time, the Bureau of h!tines has set up a demonstration mine on a Xavy shale reserve in Colorado in order t o determine how shale can best be brought out into the open. The Bureau of Mines and private companies have studied the preparation of a crude shale oil from the mined shale and the preparation of salable refined products from the crude shale oil. The present paper describes one initial method of attack upon the latter phase of the oil shale problem-preparation of salable refined products from crude shale oil. Organic matter in oil shale is believed t o exist in t h e form of “kerogen,” a solid consisting of hydrocarbons in combination
with sulfur, nitrogen, and oxygen (6). In this, it differs fiorn crude petroleum, which exists as such in the pores of porous oil sands. Crude shale oil produced from the oil shale by decomposition of the kerogen by means of heat also differs from crude petroleum, in that it is highly unsaturated and has an extremely high content of nitrogen compounds. The presence of these nitrogen compounds in shale oil is believed to be responsible for the poor color stability and disagreeable odor of the products derived from it. It is this property of crude shale oil which makes necessary additional treating xhen shale oil is refined by conventional petroleum refining procedures. Established procedures for shale oil refining generally involve a combination of cracking plus distillation for separation into the various boiling range products and treatment of these products with sulfuric acid for removal of nitrogen compounds (1, 6). Such chemical refining treatment for improvement i n color btability and odor must of necessity be very carefully controlled in order t o prevent excessive losses of valuable reactive unsaturated hydrocarbons which occur in the shale oil by reason of the method of its preparation (destructive distillation of kerogen). I n an attempt t o minimize treating losses and thereby preserve volume, hydrogenation of the total crude shale oil was investigated. Recently published work by the Bureau of Mines (4)describes one manner of applying hydrogenation to the refining of shale oil.
I
March 1952
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
This involved medium pressure hydrogenation (1500 pounds per square inch gage) of a shale oil coke still distillate for the production of essentially jet fuel, Diesel fuel, and coke. At the time of the work carried out a t the Esso Laboratories, however, emphasis was on the reduction of sulfur and nitrogen t o the levels usually met with in crude petroleum, with minimum degradation in boiling range. I n this way, it was believed that a refined shale oil or synthetic crude oil could be produced, which would then be amenable t o further processing by conventional crude refinery technique. B y distillation, fuels of various boiling ranges could be cut from the refined shale oil and satisfactorily finished in high yield with a minimum of treating. If maximum gasoline and distillate heating oil were desired, the refbed shale oil could be catalytically cracked; Mills (7) and others have shown that the removal of nitrogen compounds from a catalytic cracking feed stock is desirable in order t o maintain cracking catalyst activity and reduce carbon formation.
587
from it without some sort of a preliminary dewaxing or visbreaking operation. An operation of this sort at the retorting site would also be a necessity if the shale oil were t o be transported any great distance by pipeline between t h e retorting site and t h e refining site. During the preliminary hydrogenation studies, it was demonstrated that the pour point of the crude shale oil could be successfully reduced from 90" F. t o below -30" F. with little formation of light ends b y means of a light thermal cracking operation. However, for the hydrogenation work itself, the total crude shale oil was used as the feed stock without being visbroken, since it was more readily available and required no extra effort in its preparation, thereby allowing more attention t o be devoted to what was believed t o be the more critical part of the process, t h e satisfactory removal of sulfur and nitrogen from the crude shale oil without excessive light end formation and without excessive loss in catalyst activity. HYDROGENATION OF SHALE OIL
TABLEI. INSPECTION OF TOTALCRUD^ SHALE OIL BUREAUOF MINESNTU-TYPE RETORT Gravity 'API Nitrogeh, wt. % Sulfur, wt. % Hydrogen, wt. 3 '6 Carbon, wt. % Pour point, O F. Viscosity a t 122' F., S.S.C., sec. sec. Viscosity a t 210" F., S.S.U., Color Aniline point, F. Bromine No., cg./g. Refractive index, nso Specific dispersion, F-C Acid No mg KOH/g. Ash (tot&, wt. % Ash (insoluble), wt. % Ash (soluble), wt. Yo (by difference) Conradson carbon, wt. % Asphaltenes, wt. % Distillation Initial F. 5 % at'" F. 10% a t F. 5 0 4 at F 90% a t F: % a t 700' F.
A.S.T.M. 380
500 540 670
..78
FROM
19.0 2.0 0.9 11.4 86.3 90
237 54 Black Too dark Too dark Too dark Too dark 1.8 0.026 0.013 0.013 4.4 2.8 10 Mm. Converted 370 480 630 770 1030 33
Although it was realized from previous hydrogenation experience that increased degree of hydrogenation and better maintenance of hydrogenation catalyst activity would be more readily accomplished by the use of a lower boiling distillate feed stock, feed pretreating methods such as redistillation or coking were not resorted to (except in a few preliminary runs), in order to minimize any losses. I n addition, cracking during hydrogenation --as avoided as far as possible in order to minimize the production of low octane gasoline and minimize the recovery of the higher boiling shale oil fractions. INSPECTION OF TOTAL CRUDE NTU SHALE OIL
The material used for the preliminary hydrogenation study consisted of the total crude shale oil as produced from oil shale by the Bureau of Mines in its N T U (Nevada-Texas-Utah) type retort operated a t the oil shale site a t Rifle, Colo. Inspections on the material as received are presented in Table I. Consideration of these inspections led t o the conclusion that the total crude shale oil was a heavy, black, high-boiling liquid of high pour point containing considerable quantities of sulfur and nitrogen compounds, asphaltic material, and suspended insoluble solids (presumably entrained shale rock fines). These suspended insoluble solids were found t o be removable by filtration; accordingly, all hydrogenation work on the total shale oil was carried out on the well-filtered material. In view of the relatively high pour point of the crude shale oil, it would not be expected that salable products could be prepared
Initial evaluation of catalyst activity for different catalysts was made in small continuous units a t conventional hydrogenation conditions. This equipment has been described (3). The most promising results from this preliminary work were obtained by the use of an unsupported mixed sulfide catalyst (nickel plus tungsten sulfide) in fixed-bed liquid phase operation a t 3000 pounds per square inch gage pressure. Typical data from this type of operation are presented in Table 11. With a hydrogen consumption of about 1000 cubic feet per barrel, about two thirds'of the nitrogen was removable with 103 volume % product recovery and a catalyst activity loss rate of only 0.5" F. per day when using the undistilled shale oil (relatively free from insoluble suspended solids). If a useful operating temperature range of only 100" F. ifi assumed, a catalyst life of about 6 months is indicated. Operation a t a higher level of hydrogen consumption would be expected t o reduce the catalyst life slightly.
TABLE 11. HYDROGENATION OF FILTERED TOTAL CRUDENTU SHALEOIL
Catalyst R u n length, hours Maximum temperature, F. Catalyst activity loss rate, F./day Feed rate, vol./vol./hour Exit gas rate, cu. feet/bbl. feed Pressure, Ib./sq. inch gage Product yield, vol. % H 2 consumption, cu. feet/bbl. (approx Product inspection Feed Gravity, OAPI 19.0 Sulfur, wt. % 0.9 Nitrogen, wt. o/ 2.0 Hydrogen wt. 11.4 Carbon, w't. % 86.3 A.S.T.M. distillation Initial F. 380 5% a t 500 10% a t O F. 540 50% a t O F. 670
%
k.%:
NiS
+
WS2 706 700-71 5 0.5 0.5 6000 3000 103 1000
29.0 0.1 0.7 13.1 86.3 250 450
500 700
For more complete evaluation of the hydrogenated shale oil product, additional quantities of this material were prepared from the filtered total crude shale oil in a continuous hydrogenation unit similar t o the equipment used for the preliminary evaluation of catalyst activity but of somewhat larger catalyst capacity. In order t o determine the effect of degree of nitrogen removal on product quality, a series of hydrogenated products was made a t various levels of hydrogenation severity (various hydrogen consumptions). I n Table 111 are listed the properties of the total hydrogenated products prepared for subsequent workup. Product yield was higher a t the higher hydrogen conSumption levels; in all cases, however, the product yield was over 100 volume %. Product quality (gravity elevation and sulfur and nitrogen elimination) also improved, the degree of improvement increasing as the hydrogen consumption increased. With a hydrogen consumption of 1400 cubic feet per barrel, about SO% of the nitrogen
I
INDUSTRIAL AND ENGINEERING CHEMISTRY
588
'TABLE111. HYDROGENATIOX O F FILTERED TOTALCRUDE N T U SHALEOIL O V E R NICKEL STJLBIDE-TUNGSTEN SULFIDE CATALYST Maximum temperature, F, Feed rate vol./vol /hour Exit gas rAte, cu. fe&/bbl. feed Pressure, Ib./sq. inch gage Product yield, vol. % Product inspection Feed Gravity, "API 19.0 Sulfur, wt. % 0.9 Nitrogen, wt. % 2.0 Hydrogen, wt. % 11.4 Carbon,,wt. % 86.3 Pour point, F. 90 A.S.T.M. distiLlation Initial;. F. 380 5% at 500 10% a t ' F. 540 50% at F. 670 Hydrogen consumption, cu. feet/bbl. feed a Not determined.
i?
690 1.8
740 750 770 0.5 0.5 1.0 . . . . . . . . . . . .,6000. . . . . . . . . . . . . . . . . . . . . . . . . .3000 . . . . . . . . . . . . . 104 105 107 ..
25.1 0 10 1.4 12.4 85.8 90
28.9 0.03 0.8 13.0 86.1 90
31.2 0.10 0.4 13.4 86.4 90
34.2 0.05 0.1 13.6 86.6
..
350 470 510 700
320 430 480 690
a
a
600
900
1400
ca. 1800
TABLE IV. 400' F. ENDPOINT GASOLIKE YIELDAND H I consumption, cu. feet/ bbl. crude shale oil 0 Gasoline, vol. % on crude shale oil 2 Gasoline inspections Gravity, 'API 38.3 A.S.T.M. distillation 107 a t O F. 320 5 0 g at O F 360 90% a t 0 F: 390 Residue, 3'% Octane No. A.S.T.M. clear 66.7 CFR-research clear 77.2 do 2 ml. TEL/gal. 80.4 A.S.T.M. gum, mg./100 ml Sulfur wt. % 0:98 Nitroien, wt. % 1.52 Bromine No., cg./g. .. Aniline point, F. 70 Color Black
..
+
.
Doctor test Corrosion
was removed with 107 volume % product recovery. At 1800 cubic feet per barrel, 95% of the nitrogen was removed. The disagreeable odor of the ram shale oil was niarkedly improved by hydrogenation, particularly when the hydrogen consumption was above 1000 cubic feet per barrel. PRODUCT DISTRIBUTION AIVD QUALITY
The shale oil products hydrogenated over nickel sulfide-tungsten sulfide catalyst (Table 111) were evaluated by distillation into various boiling range fractions. Distribution of boiling range
R E S I D U A L FUEL
7 0 0 ° F . t BTMS.
Vol. 44, No. 3
D.N.P.d D.N.P.
600
900
5
8
47.4
50.9
290 340 370
1.0
QCALITY
1400 9Q
9
260 320 370 1.0
.. .. .. 83
..
51.5 260
,.
..
330 360 1.0
.. .. ..
44.lb 44.0b
..
..
41k' 26 0.07 0.07 0.02 0.48 0.33 0.92 15 6 3 129, 133, 117,
(29)' ' ( 0 .'1.1 )
..
.. (121/2
Robinson) (D.N.P.) (Pass)
... .
Inspections in parentheses obtained after acid treating (3 lb. 98% HnSOdhbl.) a n d rerunning. b After rerunning and inhibiting. Darkened rapidly on standing in contact with air. d Does not pass.
TABLEV. 300'
TO
550" F. KEROSENE YIELD A N D
Hz ronsumption, cu. feet/ bbl. crude shale oil 0 Kerosene, vol. % on crude shale oil 12 Kerosene inspections Gravity, 'API 34.4 Black Color Flash (tag closed cup), F. Sulfur, wt. % Nitrogen. wt. 7% Brpmine No., c g . / g . Aniline point, O F. I.P.T. smoke point, mm. A.S.T.M. distillation Initial b.p., O F. 10% a t O F. 50% a t F. 90% at O F. Final B.P., F.
151
0.86
1.42
..
35 14 350 410 460 510 530
600
900
13
22
24
36.9
39.3
39.6
&VAI.ITY
1400 (22)a
..
(lZ'/i
Robinson) 158 138 0.09 0.02 1.30 0.67 7 14 122 133 20 17
146 0.07 0.61 3 164 20
390 410 450 500 540
360 400 460 630 580
340 390 450 500 530
.. (0.23,
..
(20) '
'
..
..
.. ..
..
Inspections in parentheses obtained after acid treating ( 5 Ib. 98% HzSOa/hbl.) a n d rerunning. b Darkened rapidly on standing in contact with air. 5
DIESEL FUEL 400-700 OF.
KEROSENE 300-550°F
HYDROGEN CONSUMPTION, C F / B R L .
S H A L E OIL
Figure 1. Composition of Hydrogenated Shale Oil
fractions within the total product a t the various hydrogen consumption levels employed is shown in Figure 1. At the higher hydrogen consumption levels, the yields of gasoline, kerosene, and Diesel fuel (distillate fuels) increased a t the expense of the 700" F. bottoms fraction (residual fuel). Data obtained on the yield and quality of the various boiling range fractions a t the various hydrogen consumption levels are presented in Tables IV, V, VI, and VII. The color of the total hydrogenated product varied from a deep brown-black t o a light yellow TYith increasing hydrogen consumption (up to 1400 t o 1800 cubic feet per barrel). Color stability of the various boiling range fractions cut from the total hydrogenated product also appeared to improve with increase in degree of
+
TABLE VI. 400'
TO
700" F. DIESELFUELYIELDAND
Hz consumption, cu. feet/ bbl. crude shale oil 0 Diesel fuel, voi. % on crude shale oil 29 Diesel fuel inspections Gravity, "API 27.8 Color N.P.A. Black Flash'(Pensky), O F. 235 Sulfur wt. % 0 . 85 Witroien, wt. % I . 6: Bromine No., cg./g. 107' Aniline point, O F. Diesel index 30 Cetane number (est.)c 41 Cetane number (determined) Vis./lOOo F., S.S.U., 880. 46 Pour F. 30 CorrAsion cu strip 0.27 Conradso; carbon, wt. % Conradson carbon on 10% Btms., wt. % 4.0 Ash. wt. 3'% Bottom sediment and water, vol. % A.S.T.M. distillation 440 Initial b.p., ' F. 490 1 0 7 at F 560 50% at F: 90% a t F. 640 Final b.p., F. 670
..
..
..
600
900
36
41
31.1
1400 44
33.1 b
b +9 .
