July 15, 1932 TABLE
INDUSTRIAL AND ENGINEERING CHEMISTRY
L = 0.56 M - 0.63 D E = M - 1.92 L
VxII. ANALYSISO F MIXTURESFROM TABLE v M
D
OLEFINFOUND
12.7
4.6
16.8 28 4
9 6 16.1
4 . 7 octylene 4 . 2 limonene 10.3 3 4limonene octylene 1 7 . 3 octylene 5 . 8 limonene
MIXTURE
%
%
4.56 octylene 4 . 3 9 limonene 10.18 3.67 limonene octylene 17.60 octylene 5.60 limonene
As already stated, a solution containing octylene and limonene, upon treatment with sulfuric acid under the specific conditions given, results in a distillate containing the equivalent of 7 per cent of the limonene and 89 per cent of the octylene added. The olefin content, D,in terms of octylene is then
D
=
0.89 E
+ (0.07 X
1.92) L
(5) By the simultaneous solution of Equations 4 and 5, the values of E and L are obtained.
321
(6) (7)
Mixtures 1, 2, and 3, Table V, were analyzed with satisfactory results, shown in Table VIII. The method can be applied to pinene and linalool, and probably to other terpenes and terpene alcohols. However, it is very limited in its scope as, for example, trimethyl ethylene is wholb Polymerized and 3-methYlcYclohexene is two-thirds polymerized. LITERATURE CITED Faragher, Gruse, and Garner, J. IND.E m .CHEM, 1 3 , 1 0 4 4 (1921). Faragher, Morrell, and Levine, Ibid., Anal. E d . , 2, 18 (1930). Meyer, Ann., 380, 212 (1911); Ber., 45, 2860 (1912). Soden and Zeitschel, Ibid.. 36, 266 (1903). (5) Stoermer and Becker, Ibid., 56, 1447 (1923).
(1) (2) (3) (4)
RECEIVED February 23, 1932.
Approximate Determination of Olefin and Aromatic Hydrocarbons J. C. MORRELL AND I. M. LEVINE, Universal Oil Products Co., Chicago, Ill.
A
METHOD has been described for the determination of olefin and aromatic hydrocarbons (2) in cracked gasolines involving the determination of the sum of the concentration of these hydrocarbons, the removal of the olefins by means of sulfur monochloride and distillation from the reaction products, and finally, the determination of the aromatic hydrocarbons in the olefin-free oil. Where the work is of such nature that an absolute error of 1 to 3 per cent is acceptable, the time may be shortened considerably by the use of the method described herein. The sum of the olefins and aromatic hydrocarbons is determined in a manner in which the technic is modified slightly from that described in the previous article. The olefin concentration may then be calculated from the weight of residue remaining after distillation of the oil obtained upon treatment with 91 per cent sulfuric acid by the use of empirical formulas developed in this work. Obviously, the aromatic hydrocarbon content constitutes the difference between the total volume per cent of olefin and aromatic hydrocarbons and the olefin concentration. All values of concentration in this work are expressed in terms of volume per cent.
ice in the condenser and with the receiver in an ice-water bath, the loss may be assumed to be 1 cc., which is the average loss sustained in the many distillations made in this work. The distillate is transferred to the same funnel used for the 91 per cent sulfuric acid treatment, and treated with 3 volumes of 98 per cent sulfuric acid in the manner described above. The treated oil is measured and weighed in the graduate used heretofore, and its specific gravity calculated. The total volume per cent of olefins and aromatic hydrocarbons is calculated according to the formula
s
=
v, - (V, + I )
(1)
where VI is the volume of the original oil, VZ the volume of oil remaining after the second acid treatment, and I the average distillation loss. The following equations showing the relationship between the weight of the distillation residue and olefin content were developed empirically : A: For gasolines with a olefin content)
P
factor of 10 t o 25 (15 to 35 per cent
P U = 1.3 (2) D OF TOTAL OLEFIN-AROMATIC HYDROCARBON DETERMINATION P CONTENT or U = D- + 6 (3) The oil (100 cc.), measured in a weighed graduate, is P shaken with 3 volumes of 91 per cent sulfuric acid for 30 factor of 25 to 35 (35 t o 50 per cent minutes in a 500-cc. separatory funnel. The mixture is B: For gasolines with a olefin content) allowed to settle for 30 minutes, the acid layer withdrawn, and the oil permitted to stand 30 minutes longer, any sludge P U = 1.4 accumulating being withdrawn in the meantime. The D stopcock and stem of the separatory funnel are also freed from U = BP + l 3 or sludge. The oil is transferred directly into a weighed 200-cc. short-neck round-bottom flask, from which the oil is distilled P to a temperature 5" above the end point of the original oil, C: For gasolines with a 3 factor of 35 to 40 (50 to 60 per cent as previously determined in a similar manner. The flask is olefin content) provided with a small uninsulated Hempel column (effective P size 3 by 0.5 inches). The weighed graduate is used as a U = 1.5 (61 D receiver. P The distillation loss may be determined from the weight U D L,+ 15 (7) or loss and the density. If the distillation is carried out with
+
ANALYTICAL EDITION
322
where P is the weight of the distillation residue, L the loss in volume per cent sustained on the treatment with 98 per cent sulfuric acid subsequent to distillation, and D the density of the oil remaining after the 98 per cent acid treatment. As applied to the present work, Group A corresponds roughly to gasolines produced by cracking processes operating a t temperatures of 400480" C., Group B a t temperatures of 480-510" C., and Group C a t temperatures of 510-570" C. The temperature relationship may be highly limited, as the time-temperature factor is controlling in this respect. For use of Formula 7, the volume of distillate a t room temperature must be known in order to determine L. Otherwise, even this reading need not be considered. The volume of oil, V T , at room temperature, T, may be calculated from the observed volume, V , and the observed temperature of the distillate, t, according to the formula VT =
vt (1
+ G)
Vol. 4, N o . 3
to a portion of the latter appearing as condensation products with octylene, balancing the portion of octylene dissolved in the acid. On the other hand, the ratio for amylene is very high, 2.5, indicating great solubility of the olefin in the acid. This value decreases to 1.4 when aromatic hydrocarbons are also present. It is interesting to note that olefin-residue ratios may vary with the boiling range of gasoline. For a Group A gasoline, the fractions boiling within the ranges 64" to 95", 95" to 125", 125" to 150°, and 150" to 180" C., the ratios are 1.4, 1.2, 0.93, and 0.94, respectively. For the fractions of a Group C gasoline boiling between 60" to 95", 95" to 125O, 125" to 150", 150" to 175", 175" to 200°, and 200" C. to the end point, the ratios were 1.4, 1.2, 1.2, 1.2, 1.6, and 2.0. Removal of a part of the olefins, as may be done by treatment with 80 per cent sulfuric acid, changes the ratio from 1.3 to 1.1. This result clearly shows the effect of the absence of the olefins that are readily soluble in the acid.
OLEFIN-RESIDUE RATIO As has been stated in the literature ( I ) , several types of reaction take place between sulfuric acid and olefinsnamely, esterification, alcohol formation, oxidation, polymerization, and condensation with aromatic hydrocarbons when the latter are present. Another complex reaction takes ACCORDINQTO GROUPA TABLEI. ANALYSISOF DISTILLATES place in which the products are saturated hydrocarbons -OLEFIN CONTENT(3, 4,6). To what extent each of these types of reaction Observed Calculated ANALYSIS CRACKED DISTILLATElSaClz method) Ea. 2 Ea. 3 occurs depends chiefly upon the concentration of acid used % % % and the nature of the olefin. Therefore, when an oil is California 21.4 22 22 1 treated with 91 per cent sulfuric acid, the concentration of 2 Panhandle 32.8 34 32 Seminole 29.1 20 20 3 products remaining in the oil and appearing as residue upon Pennsylvania 25.6 25 4 25 Venezuela 20.0 20 22 distillation-i. e., the polymerized products-is a function of 5 West Texas (Pecos) 32.8 32 30 0 the type of olefins. Mexican (Panuco) 27.3 28 27 7 Smackover 31.1 32 30 8 Examination of the analyses has shown that the ratio 28.0 Pennsylvania 27 20 9 Pennsylvania 28.7 29 28 10 between the olefin content of a gasoline obtained from a Midcontinent 30.9 28 27 11 cracked distillate and the distillation residue in these analyses Midcontinent 29.8 27 20 12 is fairly constant. This shows that regardless of the source An overhead distillate, boiling range 210" to 258" C., and composition of the charging stock, the mixture of the from a Midcontinent pressure distillate was analyzed. It olefins formed upon cracking consisted of the same types contained 16.2 per cent olefins according to the sulfur chlo- in the same relative proportions. The calculation showed, ride method, and gave 17 and 19 per cent, respectively, for therefore, that for Group A three-quarters of the olefins originally present in the gasoline are found in the residue as the olefin content, according to Equations 2 and 3. reaction products. The constancy of the olefin-residue OF DISTILLATES ACCORDING TO GROUPB TABLE11. ANALYSIS ratio (V to P/D)seems to hold for distillates obtained from --OLEFIN CONTENTvarious charging stocks and methods of processing, and Observed Calculated depends principally on the operating conditions, particularly ANALY~ISCRACKED DISTILLATE (Sacla method) Eq.4 Eq. 5 41, 41, 4," 1", the time-temperature history, of the cracking operation. 1 Midcontinent kerosene 44.4 ,45 45 Other factors being equal, increase in cracking temperatures 50 2 Pennsylvania kerosene 48.3 52 45 3 Pennsylvania fuel oil 47.9 45 produces gasolines with increased olefin-residue ratios. Hence, not only is the total olefin content greatly increased, A preliminary test indicates that oil obtained by polymeriz- but the ratio of acid soluble to total olefins is also increased. ing ethylene falls in Group B. This increased solubility is an indication of the presence of the more reactive olefins, and thus of the gum-forming conTABLE 111. ANALYSIS OF DISTILLATES ACCORDING TO GROUPC stituents. I n some types of gasoline the olefin-residue ratio -OLEFIN CONTENTmay also bear a relationship to the antiknock properties of Observed Calculated the gasoline which increase with this ratio. As a consequence, ANALYSI8 METHOD (SeCIz method) Eq.0 Eq. 7 % % % the antiknock value and gum content should increase a t a greater rate than the olefin content.
Several cracked distillates were analyzed using the more accurate method previously referred to (sulfur monochloride), and the results were compared with those determined by the present method using Equations 2 to 7, inclusive. These results are shown in Tables I, 11,and 111.
,I
,I
LITERATURE CITED Equation 7 gives better results than Equation 6.
DISCUSSION It should be stressed that the formulas given for the calculation of the olefin content are purely empirical. Whereas the olefin-residue ratio for Group A gasolines shown in Table I is about 1.3, that of octylene in the presence of aromatic hydrocarbons is only 1.0. This is probably due
(1) Brooks and Humphrey, S. Am. Chem. SOC.,40, 822 (1918). (2) Faragher, Morrell, and Levine, IND.ENQ.CHEM.,Anal. Ed., 2 18 (1930). (3) Maquenne, Compt. rend., 114,918 (1892). (4) Ormandy and Craven, J . Inst. Petroleum Tech., 13, 311, 846 (1927); 17,185 (1931); S.SOC.Chem. I n d . , 47, 317 (1928). (5) Renard, Compl. rend., 119,652 (1894). RECEIYBD February 23, 1932. Presented before the Division of Petroleum Chemistry at the 78th Meeting of the American Chemical Society, Minneapolis, Minn., September 9 t o 13, 1929.
