November, 1945 (4)
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Brown and Hauser, IND.ENQ.CHIPY., 30, 1291 (1938); Rubber
Cham. Tech., 12, 43 (1939).. (6) Busee, IND.ENQ.CEEm., 24,140 (1932); Rubber C h . Tech., 5, 164 (1932).
(6) Cheyney and Duncan, IND.ENQ.CHEY.,36,33 (1944); Rubber
Chem. Tech., 17, 412 (1944). (7) Cheyney and Robinson, IND. ENQ. Cmnm., 35, 976 (1943); Rubber Chem. Tech.,17, 124 (1944). (8) Cotton, Tram. Imt. Rubber I d . , 6, 487 (1931); Rubber Chem. Tech., 5, 153 (1932). (9) Farmer and Michael, J . Chem. ~ o c . ,1942,613. (10) Fisher, IND.ENQ.Cmm., 18, 414 (1926). (11) Ibid., 31,1381 (1939); Rubber Chum. Tech., 13,60 (1940). (12) Fry and Porritt, Tram. Imt. Rubber Ind.. 13, 203 (1927); Rubber Chem. Tech., 1,299 (1928). (13) Garvey and Forman, IND.ENQ.Crinm., 30,1036 (1938); Rubber Chem. Tech., 11, 680 (1938). (14) Hauser and Brown, END.ENQ.CHEm., 31, 1226 (1939); Rubber Chum. Tech., 13, 65 (1940).
1089
(15) Kemp, IND.ENQ.CHIPM., 19,531 (1927). (16) Kemp and Mueller, IND.ENQ.CHEM.,ANAL.ED., 6, 62 (1834); Rubber C h . Tech., 7,576 (1934). (17) Kemp and Peters, IND.ENQ.CHIPY., ANAL.ED., 15, 453 (1943); Rubber C h . Tech., 17, 61 (1944). (18) Kemp and StraititT, IND.ENQ.CEEM.,36, 707 (1944); Rubber Chem. Tech., 18, 41 (1945). (19) Sebrell, IND.ENQ:Cnsm., 35, 736 (1943); Rubber Chem. Tsch., 16.713 (1943). (20) Selker and Kemm IND.ENQ.CHEY.,36, 16-28 (1944): Rubber C h . Tech., 17,303 (1944). (21) Thornhill and Smith, IND.ENQ.CEEM.,34, 218 (1942); Rubbar C h m . Tech., 15, 272 (1942). (22) Whitby, Tram. Imt. Rubber Id., 6, 61 (1930); Rubber C h a . Tech., 4, 466 (1931). (23) Williams, in Davis and Blake’s “Chemistry and Technology of Rubber”, A.C.S. Monograph 74, p. 244, New York, Reinhold Pub. Corp., 1937.
Octane Number and
Lead Susceptibility of Gasoline EFFECT OF ORGANIC CHLORINE AND SULFUR CLARK HOLLOWAY, JR., AND W. S. BONNELL’ Gulf Research & Development Company, P i t t s b u r g h , Pa.
Small quantities of organic sulfur are instrumental in lowering the octane number and decreasing the lead susceptibility of gasolines. In order to ascertain whether organic chlori,ne in gasoline would have a similar effect, synthetic samples containing from 0 to 1.0 weight % chlorine as organic chlorides were prepared and tested for motor-method octane number, lead susceptibility, corrosion, and gum. The gum and corrosion tests were negative at chlorine concentrationsof 0.1 weight % and lower; the effect of organic chlorides on lead susceptibility was so great as to indicate that, above 0.001 weight %, chlorine should not be tolerated in gasoline, although this limit might be raised somewhat, depending on whether the particular chlorides present are normal, secondary, or tertiary. Work with another gasoline, and using 1-C aviation-methodoctane ratings indicated about the same permissible concentration, both for organic chlorides and for a number of organic sulfur compounds.
T
HE very deleterious effects of organic sulfur on octane number and lead susceptibility are well known and have been quantitatively reported (I, 8 ) . Similarly, A. M. McAfee, of Gulf Oil Corporation, observed that small quantities of organic chlorine introduced into gasoline in the use of an aluminum chloride catalyst decreased the lead susceptibility. This paper presents data showing the effect of six organic chlorides on leaded and unleaded motor-method octane number (A.S.T.M. D-367) as well as on gasoline corrosion and gum tests, together with information on the effects of organic chlorine and sulfur on the aviation 1-C octane number (A.S.T.M. Tentative Method D-614). Present addresa, Gulf Oil Corporation, Port Arthur, Texas.
Three C.F.R. standard secondary reference fuels were used; they boil in the aviation gasoline range and have the following octane numbers: Fuel c-12
M-3
sa
A.S.T.M. Octane No. 78.9
19.6
100.0
The tetraethyllead w w the standard automotive type ‘ked” fluid where A.S.T.M. octane numbers are reported and the standard aviation type “blue” fluid where 1-C octane numbers are given, both from the Ethyl Corporation. With the excep tion of the ethyl chloride which was a C.P. grade by the Du Pont Company, the organic chlorides and all of the sulfur compounds were obtained from Esstman Kodak Company and were better than 95% pure. After the respective chlorides were added to the C-12 fuel, the gasoline samples were analyzed for chlorine by burning in an atmosphere of oxygen and carbon dioxide. The combustion products were absorbed in sodium carbonate aolution, and the chlorine was precipitated as silver chloride with standard silver nitrate solution, using potassium chromate aa indicator. Errors in the analyses by this method were no more than 3y0a t chloride concentrations of 0.01 weight yoand greater, and were only 13y0 a t concentrations as low as 0.002 weight 70. This method of analysis is a modification of one p#eviously desoribed (4,with equipment similar to that used in the determination of small quantities of sulfur ( 9 ) . Since good checks were obtained with the compositions as made up by weighing, analyses were not carried out on samples used in the 1-C determinations. I n addition to the octane number study, four standard corrosion and gum tests were made on the C-12 gasoline samples: copper strip (A.S.T.M. D-130-30), corrosion and residue (FSB 530.11), gum (AN-W-F-781; F-54, and acidity of distillation residue [AN-W-F-781; F-5e(7)]. Data for this gasoline are
Vol. 37, No. 11
INDUSTRIAL AND ENGINEERING CHEMISTRY
1090
I -?.
$105
I.'
104,
-
--.. ---
TERTIARY CHLORIDES 0.1 W T % C L IN S-2
+ 4 CC.TE.1
0.1 W T . k C L l N C-1'2 +I cc. T E L
I
I
8 80 6r
0
0.001 WEIGHT
0.01 0.1 PERCENT CHLORINE
1.0
Figure 1. Effect of Organic Chloride Concentration on Octane Number
compiled in Table I. The only failure to meet aviation gasoline requirements was in the case of the gum test. When a sample containing 0.106 weight % chlorine as ethylene chloride was subjected to this test, 5.8 mg. of gum per 100 ml. of sample were obtained, whereas a maximum of 5 mg. per 100 ml. is allowable. Uninhibited and inhibited samples containing 1 weight % chlorine as tert-butyl chloride produced 13 and 11 mg. of gum per 100 ml. of sample, respectively. According to these results, no trouble will be encountered in meeting corrosion and gum specifications because of organic chlorides, provided the chlorine concentration is 0.1 weight % or less. EFFECT OF CHLORIDES
The octane numbers of unleaded samples containing up t o 1.0 weight Tochloride as tert-butyl chloride were not affected by the
TERTIARY
+
BUTYL
chlorine content. The octane numbers of samples containing tetraethyllead fluid, however, were appreciably reduced in the presence of minute amount of organic chlorine. This octane number depression began to occur between about 0,001and 0.01 weight % chlorine when the chloride used was the tert-butyl compound. Figure 1 shows the effect of various amounts of tert-butyl chloride. Curves are presented for inhibited and uninhibited samples containing 0 and 1 cc. of tetraethyllead per galIon, and one curve represents an uninhibited sample containing 3 cc. per gallon. I n a homologous chloride series, increasing the molecular weight progressively decreases the lead susceptibility of the gasoline. The octane numbers obtained with samples containing about 0.1 weight yo organic chlorine, using four primary chlorides and ethylene chloride, are plotted on Figure 2; 1 cc. of tetraethyllead per gallon was present in each sample of the homologous series, The octane numbers obtained in the presence of n-butyl and tertbutyl chlorides indicate that equal concentrations of isomeric chlorides act differently upon lead susceptibility; a tertiary decreases it more than a primary chloride. None of the chlorine concentrations mentioned in this work include halides added with the tetraethyllead in the form of ethylene chloride and ethylene bromide. These are present
TABLE I. SUMMARY OF CORROSION TESTSAND O C T A N E ~ U M B RATINGS ER FOR GASOLINE CONTAININQ ORQANIC CHLORIDES Chloride added Chlorine, wt. % Inhibitor added, 1b.O
0
0
0.0010 0
0.0093
0.0836
0
0
0.962 0
Copper strip test Corrosion & residue, mg./100 ml. Gum, mg./100 ml.
0
0
0
0 2
1 13
79.6 80.2
78.6 78.2
0.084
0.786
Acidity of distn. residue A.S.T.M. motor-method octane No. Clear + l cc. T.E.L. (red) Chloride added Chlorine w t 7 Inhibito; addecf, 1b.a Copper strip test Corrosion & residue, mg./100 ml. Gum, mg./100 ml. Acidity of distn. residue A.B.T.M. motor-method octane No. +1 00. T.E.L. (red) +3 cc. T.E.L.(red)
led-Butyl
0 1
0.0010 1
0.0091 1
0.100 1
0.849 1
0 0
0 1
11
79.0 87.2 n-Pro yl 0.1829
79.2 80.4 Ethylene 0.106
79.3 77.8 Ethyl 0.1003 0
2.0 5.8
1.2 3.0
84.3
84.8
Negative 0
0
0
0
0
0
4
1
Neutral 78.6 87.7
78.7 87.8
0
0.0009
0
.. ... .
0
..
78.8 86.5 lerl-Butyl 0.0073 0
0
0
.. .. ..
*.
.. .* ..
.. .. ..
..
..
... . ..
92:s
92:a
9i:e
si:2
7+:9
79.2 88.8 n-Amyl 0.1030 0
0
.. 1.8 1.8
0.8 1.8
0
Negative 2.0 2.0
0
Neutral
..
82.5
Pound6 of monobensyl-p-adnophenol per 5000 gallons.
79.0 88.9 n-Butyl 0,1019
82.8
..
83.1
..
..
..
INDUSTRIAL A N D ENGINEERING CHEMISTRY
November, 1945
about 15% in excess of the stoichiometric quantity required for complete conversion of the lead to lead halides. Thus, with the “red” fluid used, the concentrations of chlorine and bromine are 0.006 and 0.021 weight % ’ of the gasoline, respectively, for each cubic centimeter of T.E.L. added per gallon.
ya
f
I10
“---emNI isoeurYL
MERCAPT~? SULFIDE DISULFIDE W A M Y L DISULFIDE ISOAMYL U S U L F I D E THIOPHENE
-BUTYL n-BUTYL
I
I
T
Figure 3.
I
I ]
I
0.001 0.0 I 0.05 WEIGHT PERCENT SULFUR
0.1
Effect of Organic Sulfur Compounds on 1-C Octane Rating
Tests were also conducted to dctermine the effect of organic chlorine and sulfur on 1-C ratings. Table I1 sumnariaes the data for leaded 6-2 reference fuel containing various concentrations of organic chlorides, and the 1-C ratings of these samples are plotted against chlorine concentration and molecular weight in Figures 1 and 2. The trends shown are considered accurate, although i t is gencrally recognized that the accuracy of single I-C ratings is only about *0.5 unit. tert-Amyl chloride was evaluated at chlorine concentrations of approximately 0.001, 0.01, and 0.1 weight yo, and the effect of four other chlorides was determined a t 0.1 weight % chlorine. With tett-amyl chloride, the 1-C rating of leaded 5-2 reference fuel started to decrease when more than 0.001 weight yo chlorine was present, although the rate of decrease was not rapid until 0.01 weight yo chlorine had been exceeded.
ganic chloride or organic sulfur compounds. For constant chlorine concentration, branched-chain chlorides had a more deleterious effect than straight-chain isomers; in general, increasing the number of carbon atoms in a homologous series decreased the 1-C ratings. These observations are in agreement with the data on the effect of organic chlorides on A.S.T.M. motor-method octane number. The data on the effect of various types of organic sulfur compounds are not very conclusive. The decrease in 1-C ratings resulting from the addition of 0.05 weight yo sulfur as n-butyl mercaptan, isobutyl mercaptan, n-butyl sulfide, n-amyl disulfide, or isoamyl disulfide was about the same; thiophene and n-butyl disulfide had considerably less effect. Ryan (2)observcd that increasing the number of branched chains in an isomeric series or increasing the number of carbon atoms for a homologousseries decreased the A.S.T.M. motor-methodoctane number of samples containing 0.05 weight yosulfur. I n our work there was no consistent difference between the two sets of isomers, normal and isobutyl mercaptan or normal and isoamyl disulfide; however, the amyl disulfides were more detrimental than n-butyl disulfide.
TABLE 111. EFFECTOF ORQANIC SULFURCOMPOUNDS ON 1-C OCTANE RATING (95% 9-2 reference fuel f 5% M-3referenoe fuel -I-4 cc. tetraethyllead) Aviation M.ethod 1-C Wt. 70 s Rating Boiling Range of Added an Cc. of Equiv. Added Sulfur Sulfur Compound, Or anic T.E.L. in blendin Compound a F. 8uhr iao-octane octane $0. None . .. 0.0 2.310 110.8” n-CdHoSH 204.8-208.4 0.01 1.29 108.4 n-CdlsSH 204.8-208.4 0.05 0.20 102.5 n-C,HeSH 204.8-208.4 0.1 0.15 101.9 iso-CdH&H 188.6-192.2 0.05 0.30 103.3 n-C4H#)& 366.8-272.2 0.05 0.30 103.3 n-C+HafrSt 212-217.4 (15mm.) 0.05 1.07 107.7 n-C*Hit):Sr 262.4-266(12 mm.) 0.05 0.80 103.3 (isoCrHii):Sr 251.&257(10 mm.) 0.05 0.42 104.3 HC-CH
. . . . ..
1
& I% H
EFFECT OF SULFUR
Added Chloride None Is+t-C*HliCl lat-CbHiiC1 ferl-CtHiiCI n-CIHlrC1 taZ-CdHsC1 n-CdHtC1 n-CsH&l Average
183.2
0.05
1.90
110.0
€‘ 3’
Table I11 summarizes the data for leaded 95% 5-2 fuel in M-3 reference fuel containing various concentrations of organic sulfur compounds, and the 1-C ratings of these samples are plotted against sulfur concentration in Figure 3. The comment on accuracy of 1-C ratings should again be kept in mind. %-Butyl mercaptan was evaluated a t sulfur concentrations of 0.01, 0.05, and 0.1 weight yo,and the effect of six other sulfur compounds ’ sulfur. Unfortunately, a 1-C was determined a t 0.05 weight % rating of a sample containing 0.001 weight yo sulfur as n-butyl mercaptan was not obtained. Since 0.01 weight yo sulfur decreased the rating by 2.4 octane numbers, it is probable that at 0.001 weight yosulfur the 1-C rating would start to decrease. I n this investigation no attempt was made to determine the inh e n c e of type of fuel or octane number level, As indicated above, some information was obtained a t 0.1 weight yo chlorine and a t 0.05 weight yosulfur on the effect of different types of or-
TABLE11. EFFECTOF ORQANIC CHLORIDEB RATINQ
1091
ON
1-c OCTANE
(8-2 reference fuel plus 4 CC. tetraethyllead) Aviation Method 1-C Rating Boiling c c . of Equiv. Ran e of Wt. % Added T.E.L. in blendin ChloriJe, O F. a8 Organic C1 iso-ootane ootane 4.060 113.50 0.0 4.16 113.6 0.0009 181.4-i‘85.o 3.62 112.9 0.0092 181.4-185.0 104.0 0.39 0.0022 181.4-185.0 112.0 2.96 0.10 222.8-226.4 105.4 0.61 0.10 122.0-123.8 112.7 3.42 170.6-172.4 0.10 2.99 112.1 113.0-116.6 0.10 of two ratinge.
80.
a
Average of t w o ratings.
I n agreement with the work on motor-method octane numbers, and again depending upon the type of compounds present, not ’ chlorine or sulfur more than approximately 0.001 to 0.01 weight % can be tolerated without decreasing the 1-C ratings. The copper-dish and gum tests were run on the samples containing up to 0.01 weight 70chlorine or sulfur, and the samples passed specifications. I n this investigation, the 1-C ratings were converted to octane numbers from the values in Report No. 3 of the Subcommittee on Blending Octane Numbers of the Aviation Gaso!ine Advisory Committee. I n the “blue” leading fluid used in the 1-C octane ratings there is no chloride. Bromine as ethylene bromide is present to the extent of 0.125 weight 7 0 of the gasoline when i t is leaded to 4 cc. per gallon. ACKNOWLEDGMENT
The writers wish to acknowledge the contribution of E. E. Nelson, who developed the method of chloride analysis, the assistance of members of the Chemistry Division of this company in preparing test samples, and the Test and Engine Laboratories’ determination of inspections and knock ratings. LITERATURE CITED
(1) Guthrie and Simmons,U. 8. Bur. Minea, Rept. Inwastigation 3729 (1943). (2) Ryan, IND. ENG.CHHIM., 34,824 (1942). (3) Schulze. Wilson, and Buell, Oil Uas J . , 37. No.45. 76 (1939). (4) Wirth and Strosa, IND. ENO.CHIM.,ANAL. ED.,5.86 (1933).
