November 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
f (observed) = friction factor calculated fromEquation 14 in which G,’ equals total flow divided by crossflow area, and Ap: is the observed value of crossflow pressure drop height of fluid head, ft. gravitational constant, 32.17 ft./(sec.)(sec.). g G = mass velocity, lb./(hr.) (sq.ft). Ga = mass velocity through baffle opening, based upon the area of the o ening less the area of the tubes passing through it, lb./(gr.)(sq.ft). crossflow mass velocity, lb./(hr.) (sq.ft.) Go = G,’ = crossflow mass velocity, lb./(sec.) (sq.ft.) = weighted mass velocity = w/X, = (cbGb)o.6, lb./(hr,) (Sq.ft.) Gt = mass velocity inside tubes, lb./(hr.)(sq.ft). G, = mass velocity parallel to tubes = total flow/(crosscross-sectional area of tubes). sectional area of shell lb./(hr.)(sq.ft.) h = coefficient of heat transfer, B.t.u./(hr.)(syft)( F.) k = thermal conductivity, B.t.u./(hr.) (sq.ft.)( F.)/(ft.) N = number of rows of tubes crossed P = tube mating, center to center, ft. P D = cl‘earance between tubes. It. S, = weighted flow area = dcrossflow area X baffle-hole area. sa. ft. sp.gr. =- specific gravity referred to water kt 60’ F. V = linear velocity, ft./sec. w = rate of flow, lb./hr. Apl = pressure drop through baffle opening, per baffle, lb./ sq. in. Ape = pressure drop across tube bundle, lb./sq.ft. Apr = total shell-side pressure drop, inches of mercury 1.1 = viscosity at average temperature, lb,/(hr,)(ft.) p,., = viscosity at tube wall temperature, lb./(hr.)(ft.) p = density, Ib./cu.ft. @ = viscosity-gradient factor,
F
4
= =
-
O
e
-
251 1
LITERATURE CITED
(1) Bowman, R. A., A m . SOC.Mech. Engrs., Miscellaneous Papers, NO. 28, 75-81 (1936). (2) Chilton, T. H., and Genereaux, R. P., Trans. A m . Inst. Chem. Engrs., 29, 161-73 (1933). (3) Colburn, A. P., Purdue Univ. Eng. Bull. No. 84 (Vol. 26, No. l ) , 37 (1942). (4) Colburn, A. P., Trans. A m . Inst. Chem. Engrs., 29, 174-210 (1933). (5) Drew, T. B., and Genereaux, R. P., “Chemical Engineers’ Handbook,” Perry, J. N.*, ed., 2nd ed., 828-9, New York, McGraw-Hill Book Co.. 1941.
(6) Gardner, H. S., and Siller, Irving, Trans. A m . SOC.Mech. Engrs., 69, 687-94 (19A7).
(7) Gardner, H. S., and Siller, Irving, unpublished tabulation of the
experimental data of reference (6). (8) Heinrich, E., and Stfickle, R., Ver. deut. Ing., Mitt. Forsch. Gebiete Ingenieurw., Heft 271 (1925). (9) Huge, E. C., Trans. Am. SOC.Mech. Engrs., 59, 573-81 (1937). (10) Keevil, C. S., and McAdams, W. H., Chem. & Met. Eng., 36, 464-7 (1929). (11) Omohundro, G. A., Bergelin, 0. P., and Colburn, A. P., Trans, A m . Soc. Mech. Engrs., 71, 27-34 (1949). (12) Pierson, 0. L., Ibid., 59,563-72 (1937). (13) Short, B. E., paper presented at the Am. SOC.Mech. Engrs.‘ Annual Meeting, Atlantic City, N . J., Dec. 1 t o 5, 1947. (14) Short, B. E., Univ. Texas Pub. No. 4324, 1-55 (1943). (15) Sieder, E. N., and Scott, N. A , , Jr., A m . SOC.Mech. Engrs., Unpublished Papers, No. 83 (1932). ENG.CnnM., 28, 1429-36 (16) Sieder, E. N., and Tate, G. E., IND. (1936). (17) Tinker, Townsend, paper presented at the Am. SOC. Mech. Engrs.’ Annual Meeting, Atlantic City, N. J., Dec. 1 to 6, 1947. (18) Wilson, E. E., Trans. A m . SOC.Mech. Engrs., 37, 47 (1915). RECEIVE~D November 5, 1947.
Synthetic Gasoline from Natural Gas J
COMPOSITION AND QUALITY F, H. BRUNER The Texas Company, Beacon, N . Y . Gasoline produced in this country by the fluidized ironcatalyzed hydrogenation of carbon monoxide is of much higher quality than that produced commercially in Europe by the Fischer-Tropsch fixed-bed, cobalt-catalyzed process. In contrast to the high boiling, paraffinic material produced over cobalt, the hydrocarbons produced by the American process are relatively low boiling and highly olefinic. The olefins are characterized as straight chain or monomethyl with the double bond in the 1-position. This permits the conversion of the gasoline to a high octane fuel or blending stock by a simple catalytic treatment. A 7-pound Reid vapor pressure, 400” F. end point naphtha has anA.S.T.M. D-357 motor octane of 82and an A.S.T.M. D-908 research octane. The synthetic fuel blends normally in straight-run and cracked products.
M
UGH publicity has been given lately to the American synthetic gasoline process known as the Hydrocol process which has reached the commercialization stage for the production of gasoline from natural gas. Most of the information thus far published has dealt with the process side of the synthesis and has given only general information as to the composition and quality
of the resulting synthetic fuel. The purpose of this paper is to present information on the hydrocarbon distribution in the gasoline fraction and to describe briefly its further processing to produce a satisfactory component for present-day motor fuels. “Synthetic gasoline from natural gas” can have a number of meanings, since there are a variety of ways of converting the hydrocarbons in natural gas into higher boiling material which might fall under the broad classification of synthetic gasoline. The term, however, as used here, is the more popular usage which refers to the product from the catalytic hydrogenation of carbon monoxide; this is by far the most practical definition. The hydrogen and carbon monoxide in turn are produced by the noncatalytic combustion of natural gas in substantially pure oxygen. This reaction results in the production of a carbon monoxidehydrogen mixture of relatively high purity having an approximate ratio of 2 volumes of hydrogen to 1 volume of carbon monoxide. The specific gasoline discussed here was obtained in Texas Company pilot units in a manner similar to that which will be employed in commercial Hydrocol units. However, as a 2 to 1 hydrogen to carbon monoxide mixture is not unique to the combustion of natural gas and as the source of the carbon monoxide and the hydrogen is not evident in the re-
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
2512
TABLEI. CHARACTER OF PRODUCTS FROM COMMERCIAL FISCHER-TROPSCH PLANTS
@.a
+
c.4
Light oil Diesel oil Wax
Normal -___ Pressure Process Olefin content, Wt. % of vol. % total 14 45 37 47 14 28 11
Medium Pressure Process Wt. % of Olefin content, total vol. 7 0 10 40 26 24 9 37 27 ..
sulting gasoline, discussion of the quality of the gasoline probably should not be referred to natural gas alone, but rather to carbon monoxide-hydrogen mixtures from any source containing approximately the above ratio of components. I n fact, most of the commercial production in Europe was obtained using a 2 to 1 hydrogen-carbon monoxide which was made by blending water gas (I to 1 Hz-CO) with hydrogen-rich gases such as those obtained from cracking coke oven gases or from “shifting” water gas with steam. Specific mention of natural gas is made in the title of this paper to emphasize that the gasoline being discussed is of the type that will be synthesized from natural gas in the first American commercial synthetic gasoline plant being constructed a t Brownsville, Tex.
Vol. 41, No. 11
550 to 700 F. and Kith extremely high throughputs. The use of pressures of 200 to 500 pounds per square inch makes the process very productive per unit volume of catalyst and in general provides an economical means of converting natural gas into gasoline, The quality of the gasoline also greatly surpassed that produced by the European process, being in general lower boiling and more olefinic. A comparison of the distribution and character of the products from the Hydrocol process and the medium pressure Fiseher-Tropsch process is given in Table 11. It is evident that much more naphtha is produced in the Hydrocol process and that much more polymer is potentially available due to the greater abundance and increased unsaturation of the C Bto Cq fraction. TABLE 11. COMPARISON OF PRODUCTS FROM HYDROCOL PROCESS AND GERMAN MEDICMPRESSURE PROCESS Medium Pressure Process. Cobalt Catalyst Wt. % of Olefin content, total vol. 40 26 8
Hvdroool Process. Iron Catalyst Wt. % of Olefin content, total vol. % 32 82 85-90 56 8 75-85 I -
4
EUROPEAh SYNTHETIC GASOLINE
Synthetic gasoline has been produced commercially in Europe since 1936 by the Fischer-Tropsch process ( 2 ) . I n this process hydrogen and carbon monoxide (2 to 1) are passed over cobalt catalysts at 200” C. (392 F.) in fixed-bed reactors equipped with elaborate facilities for heat removal. The older units operated at atmospheric pressure, whereas later ones operated in the “medium pressure” range of 75 to 225 pounds per square inch. The synthetic oil consisted almost entirely of straight-chain paraffinic and olefinic hydrocarbons and somewhat resembled a paraffin base petroleum crude oil, Distribution of the hydrocarbon products from typical operations is shown in Table I. The products from both types of operation contained considerable material boiling above the gasoline range and were quite paraffinic. The newer medium pressure operation product was heavier and more saturated than that obtained at lower pressure. Typical inspection data for the light oil fraction (330 F. end point) are: O
O
Specific gravity Vapor pressure, atm. Off a t 167’ F., % A.S.T.M. motor octane
0,683
0 59 40 53
These figures relate to the light naphtha fraction from atmospheric pressure synthesis. The corresponding fraction from the medium pressure process had similar properties apart from the octane number which was only 45. Because of the low octane of the primary product, it was the usual practice to undercut the naphtha fraction and combine i t with gasoline obtained from cracking the heavier fractions and blending in aromatic stocks from coal hydrogenation to give fairly high octane naphthas. It is doubtful if the value of the synthetic gasoline manufactured under the European type of operation could justify the cost of production under normal peacetime economy. AMERICAN HYDROCOL PROCESS
The Hydrocol process as projected in this country during the past few years bears little resemblance to its European ancestor. I n the development of this process, the establishment of the procedure for the burning of natural gas with oxygen under carefully controlled conditions of temperature, pressure, and space velocity to produce synthesis gas (predominantly hydrogencarbon monoxide) represented a n important technical advance. The synthesis reaction proper is carried out with an iron-base catalyst in g, fluidized reactor which permits satisfactory temperature control even though operated a t higher temperature levels,
At present, there is no commercial production of Hydrocol gasoline and the data presented on the composition and quality are taken from analyses and tests on products synthesized by The Texas Company in experimental pilot units in its Beacon, N. Y., laboratories and in the larger units at Montebello, Calif. They, however, represent what is thought currently to be a good estimate of the quality of the gasoline that will be produced commercially in the near future. It is hoped that the following discussion will convey something of the nature of the hydrocarbons present and something of the antiknock characteristics of the gasoline fraction. The Hydrocol naphtha contains some oxygenated materials which were removed wherever necessary to obtain accurate analyses of the hydrocarbon portion.
’
COMPOSITION OF Car Cd, AND Cs FRACTIONS
The hydrocarbons produced in the Hydrocol process are recovered from a primary separator and are consequently only roughly separated into gas and liquid fractions. Therefore, both the gas and liquid samples containing Ct, C4, and C6 hydrocarbons were analyzed by the mass spectrograph method, and the analyses were combined in the ratio of productionof the two fractions to show the complete composition of the low boiling fraction. The composited analysis for the Ca to Cc fraction as well as for the individual fractions is shown in Table 111. The over-all high unsaturation of both the Co and C4 fractions and the large amount of 1butene, compared to the other components of the Cq fraction, are the outstanding characteristics of this stock. The isobutene to n-butene ratio also is much lower than found in ordinary refinery C4 cuts. OF HYDROCOL Cs AND C4 FRACTIONS TABLE 111. CONPOSITION
Weight % Ca Fraction CS-CI Fraction 20.2 11.6 79.8 45.7
Component Propane Propene
Cc Fraction
Isobutane n-Butane Isobutane I-Butene 2-Butene Unsaturates Wt. r0 total Isobutene/n-butene Wt. % of C4 cut
ratio
1.9 13.6 8.7 64.3 11.5
0.8 5.8 3.7 27.5 4.9
...
81.9
84.5 0.11
INDUSTRIAL AND ENGINEERING CHEMISTRY
November 1949
CIo
O U T PT.
METHYL NONENES
METHYL OGTENLS
D I M E T H Y L HEXENES
90
DIMETHYL
PENTENES
8 0 I REFLUX
VOLUME
-
I'X4'
POOBILLNIAK COLUMN
O l 3 T l L L C D , CO
Figure 1. Distillation Curve for Hydrocol C6
+ Naphtha
Table IV presents the composited results of the analyses of the Cgfractions. This fraction also shows a large proportion of the 1olefk present, with smaller amounts of the secondary and isoolefins and minor amounts of the tertiary olefins. The saturated hydrocarbons are present only to the amount of slightly more than 10% with n-pentane accounting for most of this. The mass spectrograph indicated also that there were small amounts of cyclopentane and cyclopentene present in this fraction. The iso-olefin in largest amount is the nontertiary olefin, 3methyl-1-butene. Further evidence has been obtained on the selective production of nontertiary olefins in the CSto C, fraction. I t was treated with ozone, and the resulting ozonide was decomposed by alkaline hydrogen peroxide. The resulting material would contain ketones if tertiary olefins were present in the original sample. The results of the test indicated that little, if any, ketone was present and therefore that the original C6 to C, fraction was practically free of tertiary olefins. This finding combined with the lack of tertiary olefins in the Cg fraction leads to the conclusion that nontertiary olefins are selectively synthesized in the Hydrocol process. TABLEIV.
COMPOSITION OF HYDROCOL Cg FRACTION Weight, Component Isopentane n-Pentane 1-Pentene 2-Pentene 2-If ethyl-1-butene 3-illethyl-I-butene 2-3Iethyt-2-butene Cyclopentane Cyclopentene Unsaturates, wt. % total
%
3.5 7.9 67.2 5.8 3.5 11.1 0.7 0.1
0.2 88.5
COMPOSITION OF THE Ca-400' F. FRACTION
The residue from the depentanization of the liquid sample was distilled using a 50 to 1 reflux ratio in a 1 inch X 4 foot Podbielniak column having approximately 50 theoretical plates at total reflux. Figure 1 shows the curve for the distillation with the boiling ranges for the various olefins and paraffins indicated. The plateaus for the various molecular weight ranges and especially the lower 'ones occur in the region of the 1-olefins. Molecular weight fractions were obtained from the distillation at the cut points indicated in Figure 1. The unsaturation and refractive indexes were determined for each of these fractions, and the volume yo in each of the fractions along with the olefin content are shown in Table V. The volume yo in the various ranges appears to decrease as the molecular weight increases. However, the large decrease in the CPand CIOrange may be partially due to
2513
the relatively poor fractionation used to obtain the original 400O F. end point naphtha. The hydrocarbons are uniformly unsaturated being about 85 to 90% olefinic. The refractive indexes of the 1-olefins are shown for comparison with those for the respective fractions and the agreement is quite good for the low molecular weight ranges, but the discrepancy widens in the higher boiling fractions. Since the unsaturation is uniform throughout the boiling range, this increased divergence must be explained by the existence of normal olefin isomers or by the existence of larger proportions of iso-olefins in the higher molecular weight ranges. These two possibilities were checked by obtaining an indication of the position of the double bond and by determining the amount of chain branching. I n order to obtain an indication of the position of the double bond, a Cla to Clacut was treated with ozone, followed by decomposition of the ozonide with alkaline hydrogen peroxide. The yield of formic acid indicated that the double bond was predominantly in the 1-position. Incidently an equal yield of higher boiling aliphatic acids was obtained; this gives added confirmatory evidence to the selective production of nontertiary olefins.
TABLE V. FRACTIONATION OF HYDROCOL NAPHTHA (Distillation at 50 to 1 reflux ratio in a 4 foot X 1 inch Podbielniak column) Cut Point Vol. Olefina, Refractive Of % % Index I-Olefine Cut O C. F. Yield b y Wt. at 20° C. (8) CS 75 167 .20.4 85.2 1.3870 1.3880 c7 105 221 23.4 89.2 1.4000 1.3991 Cs 130 266 18.7 89.8 1.4129 1,4090 CS 165 311 14.2 88.3 1.4230 1.4163 ClO 175 347 10.7 90.3 1.4301 1.4220 c 1 1 195 383 7.6 90.7 1.4379 1.4270 Residue 5.0 Total io0.0 Olefin content caloulated from the bromine No. on assumption of monoolefins of the indicated molecular weight.
mv
To obtain an indication of the amount of chain branching existing in the higher molecular weight fractions, a sample of gasol line was hydrogenated and the resulting paraffinic mixture was analyzed on the mass spectrograph. The hydrogenation was carried out over Raney nickel a t 400°F. and 4000 pounds per square inch gage. The hydrogenated material was carefully distilled and the hydrocarbon composition of the narrow fractions determined; the availability of standard hydrocarbons for the calibration of the mass spectrograph limited the analysis to the CSand lighter fractions. Table VI summarizes the extent of chain branching for the (36, C7, and CSfractions. The normal compound is most abundant in all cases, with monomethyl compounds accounting for substantially all of the remaining aliphatics. From the detailed analysis it was evident that even the small amount of dimethyl compounds contained only a trace of neocarbon grouping; the methyl side chains were on separate carbons. The ring compounds are grouped together .because the hydrogenation was such that any aromatics or cyclo-olefins were converted to cycloparaffins. Therefore, the figure shown in Table VI represents the total cyclics. An unhydrogenated sample was examined for benzene and toluene by ultraviolet analyses and the Ce fraction was shown to contain about 2% benzene and the C, fraction about 5% toluene. Since the amounts of cyclics exceed these values in both cases it was concluded that cycloaliphatics are produced in the process.
TABLE VI. EXTENT OF BRANCHING OF HIGHERBOILING HYDROCOL FRACTIONS Weight % Normal Monomethyl Dimethyl cyclics
CC 75.9 20.0 0.4 3.7
c7
CS
60.2 29.3 1.7 8.8
55.4 36.6 2.4 6.6
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
2514
This relatively low octane value is accounted for at least in part by the double bonds of the olefins being predominantly in the 1-position. The position of the double bond in some respects is a redeeming feature as far as octane value is concerned, since such olefins can readily be converted to higher octane material by simply shifting the double bond into the center of the molecule, Table VI1 shows the A.S.T.M. D-357 motor octanes for some of the octenes. By comparing 1-octene with 4-octene i t may be seen that such a shift of the double bond raises the antiknock value markedly. However, in going from straight-chain olefins with centered double bonds to more highly branched olefins the increase in octane is only marginal. This is fortunate since the double-bond shift can be accomplished rather simply compared to isomerizing the carbon skeleton which requires drastic treatment with accompanying large losses of material. Therefore the treatment of the naphtha has been aimed a t bond shifting to give the larger octane increase and has been accomplished by a simple catalytic treatment. This treatment not only raises the octane value of the fuel but dehydrates oxygenated compounds that are present. The yields are high and the combined carbon and dry gas yields are of the order of only 2 to 3%.
9m
2
8-
k l
-
7-
a
6-
8 0.
-I
5\
a 42
z 0 u. 30
0 2-
kK
Vol. 41, No. 11
I-
O
I
I
I
I
I
OF OCTENES (1) TABLE VII. A.S.T.M. Motor OCTANES
1-Ootene 4-Octene
2-l\fethyl-2-hepteno 2,3,4-Trimethyl-2-pentene 3,4,4-Trirnethyl-Z-pentene
From the work on the analysis of the light gas fractions and the characterization of the heavier fractions, i t was concluded that the gasoline fraction of Hydrocol product is predominantly oleh i e , with straight-chain or singly branched structure and with the double bonds mostly in the 1-position and not adjacent to the branching. Cyclic compounds are present as minor constituents and contain cyclic aliphatics as well as benzene homologs. POLYBlERIZATION O F Cs TO CA FRACTION
From the high olefin content of the Cs to C, fraction, i t is apparent that this fraction would be an excellent charge stock for polymerization. However, the quality of polymer could not readily be predicted, as isobutene, the usual copolymerization agent for making highly branched product, is present in much smaller proportions than usually found in ordinary refinery stocks. Therefore, a stock which simulated the composition of this fraction was made up and passed over Universal Oil Products phosphoric acid polymerization catalyst a t 400" F. and 500 pounds per square inch, using a 1.15 liquid space velocity. The conversion was over 90% on the basis of the olefin charged, and 88% of the total polymer boiled below 400 "E'. The 400" F. end point polymer had the following antiknock characteristics: A.S.T.M. motor octane A.S.T.M. research octane
Clear 82.4 95.4
3 MI. T E L 85.9 99.8
These values are about the same as those obtained from an ordinary refinery Ca to Cd fraction containing larger amounts of isobutene but with a different ratio of 1-butene to 2-butene. It is evident from these data that the synthetic Ca to Cq fraction will be a satisfactory charge stock for the production of high quality polymer blending stock for inclusion in the over-all gasoline. TREATMENT OF T H E NAPHTHA FRACTION
It has been shorn that the Cb-400 F. endpoint fraction is highly olefinic and that most of the olefins are straight chain or a t least only slightly brcbnched. This fraction contains some oxygcnates and has an A.S.T.M. D-357 motor octane number of about 60.
Clear 34.7 74.3
3 Cc. TEL 57.7
80.9
84.4 87.7
71.0
86.4
84.2 81.0
Typical octane improvements obtained by this treatment are shown in Table VIII. Both the S.S.T.M. D-357 motor and A.S.T.M. D-908 research octane numbers were improved extensively at both the 0- and 3-ml. tetraethyllead levels. The bromine number was also increased due to the generation of olefins by the dehydration of the oxygenates. The low tetraethyllead susceptibility reflects the high unsaturation of the hydrocarbons, and in this respect the Hydrocol naphtha resembles polymer gasoline. This marked increase in octane number, in a sense, confirms the chemical findings on the position of the double bond because such a large increase can only be explained by a shift of the double bond from the terminal position to the center of the molecule. HYDROCOL TABLE VIII. OCTANEDATAON RAWAND TREATED NAPHTHAS
Bromine No
A S.T.M. motor octane
Clear 1 cc TEL/gal. 3 cc. TEL/gal. A.S.T.M. research octane Clear
Hydrocol Naphthas Raw Treated 115 128
+ +
62.0 70 1 74 4
75.9 80 5 82 1
+ 31 ccc.c TEL/gal. + TEL/gal.
08 4 78 6 54 5
80 7 93 0 94 2
ROAD OCTANE NUMBERS O F HYDROCOL BLENDS
I n order to evaluate the over-all contribution of the synthetic gasoline to a finished product, a sample of treated Hydrocol naphtha was blended with Cg to Cd polymer in the ratio of production and brought up to a 9-pound Reid vapor pressure with n-butane. The compositions and inspection tests for this Hydrocol blending naphtha and a base gasoline, consisting of a 50 to 50 blend of thermal cracked naphtha and straight run (M-4 reference fuel), are shown in Table IX. Blends containing 0, 10, 30, 50, and 100% of the Hydrocol stock with the base gasoline
INDUSTRIAL A N D E N G I N E E R I N G C H E M I S T R Y
November 1949
____
0 ML. TEL/G/;L. /-4
3 ML, TEL/GAL.
r*
*ec-
90
00
t I-
4
P
w
70
z
4 IO
60
50
I
49
CFRR
A
/
I
I
0
RO
0
CFRM
I
2515
boiling fraction of i t to see if such blends had exceptionally good low speed road octane performance. Consequently a commercial gasoline which contained about 50% thermal cracked gasoline, 20% fluid catalytically cracked naphtha, and the remainder straight-run and alkylate was distilled to remove the initial boiling point to 200’ F. end point fraction which amounted to about 40y0 of the stock. An initial boiling point to 200’ F. fraction of treated Hydrocol naphtha was then added to the bottoms to make up the original volume of gasoline, The bromine number of the light gasoline cut was 75, and it was replaced with a Hydrocol cut having a bromine number of 162. The blend of light Hydrocol naphtha and heavy gasoline was tested by the borderline road octane method (Coordinating Research Council designation F-8A-943). The test was carried out at 0- and 3-ml. tetraethyllead levels in duplicate in each of two cars, a 1942 Chevrolet (valve-in-head) and a 1942 &cylinder Pontiac (L-head). Curves showing the average results in the Pontiac are presented in Figure 4; these curves show the borderline octane value at the indicated speed. Results obtained in the Chevrolet agreed with those obtained in the Pontiac. Within reproducibility of the test. there is no difference in the borderline octane numbers of these particular blends.
40 60 80 100 PER CENT HYDROCOL GASOLINE Figure 3. Antiknock Characteristics of Hydrocol
20
Gasoline Blends
Base stock wntained Sol50 mixture of M-4 reference fuel and thermal wracked naphtha
were tested by the Beacon road octane method (a modification of the Uniontown method). The results obtained are shown in Figure 3. There is considerable spread between the A.S.T.M. research and A.S.T.M. motor octanes, an( from this, one would predict a road octane value fairly close to the A.S.T.M. research value. However, the determined values fall closer to the A.S.T.M. motor values. The blending road octane for the Hydrocol gasoline was determined by projecting a leash squares line to the 100% value. With zero tetraethyllead this value was 81.7, and with 3 ml. of tetraethyllead per gallon i t was 89.7. The convergence of the curves for the clear and leaded values as the amount of Hydrocol naphtha is increased reflects the low lead susceptibility of this gasoline. &vera1 reports (4) have claimed that the addition of low boiling olefinic components to motor fuels improves the low speed antiknock properties of the fuel. Since Hydrocol gasoline is highly olefinic i t appeared desirable to test blends containing the low TABLEIX. COMPOSITION AND TESTSON HYDROCOL GASOLINE AND BLENDING BASE Hydrocol Gasoline
Blending Base *., ..,
...
50
fuel) ’ Tests Gravity, API Reid vapor pressure Sulfur lamp Anilink point, O E’. Acid heat F. Bromine k o . A.S.T.M. dist a F. Initial boili& point 1097 504
’
90% End point A.S.T.M. motor octane Clear 3 ml. TEL/gal. A.S.T.M. research octane Clear 3 ml. TEL/gal.
+ +
,..
65.8 9.2
... 101
234 118 99 133 222 342 394
50 56.6 2.6 0.048 11s 33 148 184 270 374 390
80.2 84.1
48.3 67.2
91.4 97.2
50.5 72.4
00
QAS0 LI NE
20
4b
20 80 60 MILES PER HOUR
Figure 4. Borderline Road Octanes of Commercial Gasoline The front end (40%)has been replaced by light HydHmol naphtha SUMMARY ANI) CONCLUSIONS
Hydrocol gasoline in contrast to commercial Fischer-Tropsoh synthetic gasoline is a low boiling and highly olefinic fuel with the hydrocarbons consisting predominantly of straight-chain or singly-branched olefins with the double bond mostly in the 1position. The high olefinicity permits conversion of both the CSto C, and naphtha fractions to high octane stocks that blend satisfactorily with petroleum hydrocarbon fractions. ACKNOWLEDGMENT
The author wishes to express appreciation to R. A. Beck, H. V. Hess, H. E. Vermillion, J. H. Shively, C. R. Reed, R. Pomatti, and his other colleagues in Beacon laboratories of The Texas Company who assisted in the above experimental work. LITERATURE CITED
American Petroleum Institute, Rese’arch Project 45. Ninth Annual Rept. (June 30,1947). (2) British Intelligence Objectives Sub-committee, Over-all Rept. No. 1, London, His Majesty’s Stationery Office (1947). (3) Doss, M.P., “Physical Constants of the PrincipaqHydrocarbons,” 4th ed.. New York. The Texas Comoanv. 1943. ( 4 ) Jordan, Jane, Petroleum Refiner, 24, i27-33 (1945); Natl. Petro(1)
leum News, 37R, 770-90 (1945). RECEIVEDNovember 24, 1948. Presented as E part of t h e Symposium on Fuel Properties before the Division of Petroleum Chemistry at the 114th Meeting of the AMERICAN CHBMICAIIL SOCISTY,St. Louis, Mo.
