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TABLEI11 Coates Formula, ....................... CIZHZZ Molecular weight, calculated.. . . . . 166 Molecular weight, found, . . . . . . . . 167 Carbon, calculated. . . . . . . . . . . . . . 86.74 Carbon, found.. . . . . . . . . . . . . . . . . 86.68 Hydrogen calculated.. , , . , . , , , . . 13.26 Hydrogen: found.. . . . . . . . . . . . . . . 13.43 Specific gravity.. . . . . . . . . . . . . . . . 0.8511 28'/4' Boiling point, 760 mm.. . . . . . . . . . . 2 15 '-2 17' 1.4640,25' C. Refractive index. . . . . . . . . . . . . . . . Molecular refraction, calculated. . , 53.13 Molecular refraction, found. . . . . . . 5 3 . 4 s
Coates and Tims CizHzz 166 167 86.74 86.30 13.26 13.50 0.84819 24'/24' 2 15 '-2 17' 1.4546,29' C. 53.13 53.24
does not resemble in the least the ordinary casinghead gasoline, Its boiling point is far too high, as is also its specific gravity. A study of the paiticular fraction boiling from 215' tjo 217' shows it to be identical with a fraction obtained by Coates and his assistants jii 1906 from the crude oil in Jennings, La.3 Schmidt and Sigwart4 have identified the series C10H18 a J . A m . Chem. 4
SOC., 1906, 384.
Ber., 1912, 1779.
Vol. 14, No. 3
and its homologs found in Louisiana petroluem by Coates as being dicyclopentyl HzC-CH2
Ii
HzC-CH2
'CH-CH
/
CHz-CHz
and its methyl derivatives, which they made synthetically. The compound CI2H2*would, therefore, be the dimethyl derivative. The higher and lower derivatives were also isolated by Coates from the South Louisiana petroleums and occur in this condensate as well. This would indicate that inasmuch as the gas deposit a t Terrebonne carries a condensate which is identical with that obtained a t Jennings, the two deposits are probably similar in formation. It might also be a slight indication of the presence of an oil pool in Terreboime, similar to that which has been found in Jennings.
Determination of Volatile Combustible Matter in Pitch Coke' By H. E. Lloyd and F. W. Yeager RESEARCII LABORATORY, THE BARRETT Co., NEWYORK,N. Y.
Within a comparatively recent period pitch coke has found use in the manufacture of electrodes, and in certain metallurgical processes where a low volatile coke of high purity is required. Since only a coke of very low volatile content possesses suficient conductiviiy to be suitable for electrode use, the accuracy of the determi, nation of volatile combustible matter (V.C. M.) in this class of material takes on new significance. The work described in the following paper indicates that uariations in these analytical results are due to uariations in the type of crucible couer used, the weight of sample, the size of crucible, and the method of calculating results. The method which giaes the more accurafe results, particularly with low volatile cokes, follows the procedure given in test A . S . T . M. 0-37-18 under the determination of volatile matter in coke, with the exception of the use of a 2-g. sample and a second 7-min. heat correction.
ERTAIK factors operative in the determination of V. C. M. in pitch coke are particularly likely to
C
affect the accuracy of the results on account of the low volatile content of the material. Considerable work has been done on this test, but the inaccuracies possible seem not to be generally recognized. The authors had occasion to determine the V. C. M. of pitch coke by two different methods, the differences in which are listed in Table I. The coke was ground in porcelain to pass a 60-mesh sieve.
Type of crucible
TABLEI-DIFFERENCESIN METHODS METHODI METHODI1 Usual shape; capacity Capsule shape; ca20 cc.; lid of usual p,acity 10 cc.; lid flat type tight-fitting inside
__
__
r r i i ~hlp i
Weight of sample Manner of heating
1.000 g . Bunsen flame 20 cm. long (temperature
Time of heating
One 7-min. period
Calculation of results, giving V. C. M . as:
Loss in weight reported in per cent of sample weight
onnoow Y"Y
'Received June 20, 1921.
"YY
P \ u . ,
2.000 g . Electric furnace 950' C. ( A . S . T . M . D - 3 7 1-"IQ>
Two intermittent 7min. periods Loss on second heat subtracted from loss on first heat and remainder reported as per cent of sample weight
Method 11,which is being used by the Aluininum Company of America for certain types of low volatile coke, has for its purpose a correction for the oxidation of the nonvolatile portion of the coke encountered during the first period of heating. This correction is based on the loss found on a second 7-min. heating. The use of a second heating correction factor was suggested by Meade and Attex,2 mho have shown that results so corrected approximate very closely the loss on heating in an inert gas. Two samples of coke gave results listed in Table 11. TABLL11-PERCENTAGE
OF
VOLATILE COMBUSTIBLE MATTER^
SAMPLE, Method I Method I1 Ratio I I 1 1 2.3 0 3 ' 1:0.13 3 6.1 3.5 1:0.57 1 All figures reported are the averages of two or more check results.
Considering the wide differences in methods used, the basic reasons for such results are apparent. However, the reason for the marked disproportion between the results on cokes of different volatile content as indicated by the ratios in Table I1 is not so evident. A brief review of the literature shows that the loss due to oxidation by the air remaining in the large type of crucible was early investigated. To minimize this loss Shimer3 proposed the use of two 15-cc. platinum crucibles, one fitting tightly within the other with the sample between. Meade and Attex4 recommended making the test in an atmosphere of nitrogen. Shimer suggested the addition to the sample of alcohol, and Parrs of kerosene, for the same purpose. The variations in V. C. M. tests due to mechaiiical losses, variations in heat, type of crucible, character of flame, type of burner, etc., have been discussed by Parr.6 Fieldner and Davis' have studied the influence of gas pressure, welling of coal, type of burner, and condition of crucible, i. e . , dull 2
J . A m . Chem. Soc., 21 (1S99), 1137.
a THIS JOURNAI,, 1 (1909), 518. 4J. Am. Chem. Soc., 'dl (1899), 1116. STHIS JOURNAL,8 (1911). 900. 6 Ibid., 4 ( l Q l 2 ) , 352. SIbid., 2 (1910), 304.
Mar., 1922
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Here the relation represented by b in terms of a is, for Method I, b = 2 . 7 a; and for Method 11, b = 7.2 a. It appears that the cause for this variation can be traced to some difference of conditions which permits unequal degrees of oxidation or combustion with respect to high and CHANGE IN SAMPLE WEIGHT low volatile cokes in the two methods, such as (1) fit of Sample 3, Table 11, was used for the tests. Table 111 crucible lids, (2) difference in relation of air volume to coke shows the results obtained in the electric furnace with both sample weight, or both. types of crucible, each with 1- and 2-g. samples. TYPEOF CRUCIBLELID TABLE1x1-PERCENTAGELOST WITH SAMPLES OF DIFFERENTWEIGHT The effect of a loose-fitting lid was tried out on the 10-cc. --WEIGHT OF SAMPLEcrucible with a 2-g. sample. A comparison of these results 1,000Gram 2 000Grams with previous ones using the usual tight lid is made in IO-cc. Crucible (Capsule Type) Table V. 1st heat, 7 min. 4.21 3.99 or bright. Fieldner8 determined the effect of change of temperature and of type of crucible. I n the present investigation attention was first given to the influence of a change in sample weight.
2nd heat, 7 min.
0.79 20-cc. Crucible 1st heat, 7 min. 5.25 2nd heat, 7 min. 2.17 1 This result is by A. S. T.M . Method D-27-18 in
0.53
4.55 1 19 all respects.
In every case the per cent loss in weight, irrespective of the size of crucible, is greatest where the sample is smallest. The cause for this is thought to be the variation in the depth of coke layer: in other words, the relative coke contact surface per gram of sample which is dependent upon the sample weight. This difference has an appreciable effect where the same crucible is used, but where the 2-g. sample is charged to the 10-cc. capsule and a I-g. sample to the 20-cc. crucible, the difference in coke contact surface between the two conibinations is considerable. Parre regards variation in this contact surface as affecting the results of tests to a considerable degree, the cause being, in his opinion, the effect of differences in coke contact surface per gram on the speed with whirh the heavier volatile constituents are discharged. The losses for the second period heats are due mainly to oxidation of the coke residue remaining after the first heat, either by the air in the crucible or that entering during the second heat. Under these conditions the coke contact surface is of less importance as a factor affecting the per cent loss and while the per cent loss is different the actual weight Ioss tends to be approximately the same for each crucible, respectively. TYPEOF CRUCIBLE The data obtained in the above tests also serve to show the difference due to the type of crucible. With the same weight of sample the loss is greater when the 20-cc. crucible is used. This may be attributed to two factors, (1) size of crucible, and (2) type of cover. I n their entirety these results show that the difference between the two methods as to type of crucible and amount of sample tend to produce a lower percentage loss in weight in Method 11. When this difference in actual per cent loss is augmented by the correction in Method I1 which further reduces the figure for V. C. M., it is readily apparent that in any case lower results are inherent in Method I1 than in Method I. However, these data do not account for the disproportionate results obtained in different cokes. The cause for this difference, as shown by Table IV, does not lie in the calculation of results, but is operative during the first 7-min. heating of the crucibles. TABLEIV-LOSS ON FIRST7-MIN. HEATING (Sample 1, low volatile coke: Sample 3, high volatile coke) METHODI METHODI1 Sample 1 Sample 3 Sample 1 Sample 3 a b a b 0.0225 0.0608 Weight loss, gram 0.0109 0.0789 Per cent loss 2.26 6.08 0.55 3.99
* 8th
Inicrnat. Congr. A p p l . Chcm., 10, 139.
TABLEV-EFFECT OF TYPEOF CRUCIBLE LID (Per cent loss, 1st heat, 7 min., furnace 950' C.) Sample 1 Sample 3 a b 10-cc. crucible, usual tight lid 0.55 3.99 1.23 4.48 10-cc. crucible, loose lid.. 2.25 6.18 20-cc. crucible, flat lid.
.............. ................ .................
b/a 7.2 3.6 2.7
These results indicate that the relative tightness of the lids, of necessity causing a difference in amount of oxidation, is closely connected with the variation of the relation between the high and low volatile coke tests; particularly when it is seen that, not only is there an increase in loss in each case when the loose lid is used, but this increase is different for cokes of different volatile content, and brings the ratio of their apparent V. C. M. to a figure approximating the ratio obtained by the 20-cc. crucible method (see b/a) . EXPLANATION O F RESULTS-The explanation Of the discrepancy in results of the two methods with samples of high and low volatile coke may be as follows: I n Method 11, with either high or low volatile cokes, the volatile matter evolved passes out of the small vent between the lid and rim of the crucible and is burned externally; during the test very little of the nonvolatile portion of the coke is consumed, on account of the protection afforded by the tightfitting lid and the generally nonoxidizing atmosphere maintained in the crucible. With Method I the amount of volatile matter evolved relative to the air accessible to it is considerably less than in Method 11, because of the smaller sample, larger crucible, and loosely fitting lid, all of which make for its quicker dissipation and more readily expose the nonvolatile portion to oxidation, which results in a V. C. M. content considerably above the actual. This is particularly the case with low volatile cokes. As the actual V. C. M. content of the coke tested increases, the combustion of the nonvolatile portion is correspondingly delayed and the results more nearly approach the true value. CONTINUOUS -4ND INTERMITTENT HEATING The high volatile coke was used in comparative tests in which the heats were made both continuous and intermittent for the same total period. TABLEVI-COMPARISONOF Loss PER CENT WITH CONTINUOUS AND INTERMITTENT HEATS 14 Min. 14 Min. 7 Min. Continuous Intermittent 10-cc. capsule, 2-g. sample, furnace 3.99 4.22 4.52 8.51 20-cc. crucible, I-g. sample, flame 6.12 8.42
The test with the IO-cc. capsule shows that the volatile matter is practically all expelled a t the end of the 7-min. period. The excessive increase in the l4-min. continuous heat with the 20-cc. crucible must be attributed to the high oxidation factor inherent to this type of apparatus. It may also be noted that the losses in the intermittent
