INDUSTRIAL AND ENGINEERING CHE-VISl’RY
July, 1926 ---TOLIDINE
Run
Time Min. 16-19 28-29 36-38 45-47 25-28 40-42 22-24 36-39 47-49 23-25 30-32 37-39
T a b l e 111-Tests in R o o m where C h l o r i n e T r e a t m e n t Was B e i n e Given IODOMETRIC METHOD METHOW----------. Reading Normality Reagent againstConcn. Time Air of used Air standard of CI reagent cc. Min. cc. cc. P. p. m. Mg./liter 500 0.07 0,007 0.03 0.00086 1.05 200 15-33 4000 0.0075 0.04 0.01 200 0.03 0,0073 0.00086 1.60 200 34-49 4000 400 0.075 0.0094 0.03 0.00086 1.62 200 0.0075 23-59 5000 0.035 500 0.0035 0.04 500 0.004 500 0.05 0.005 12-55 6000 0,00043 1.94 500 0.05 0.005 0.0055 0.055 500 500 0.055 0.0055 20-45 6000 0.00086 1.17
by the o-tolidine method, as shown in the parallel columns.
It was found difficult to obtain a constant concentration of chlorine for this work, but it will be noted that the average values obtained with the o-tolidine method check satisfactorily with the value obtained by the iodometric method over the same period of time. The results shown in Table I11 were obtained in a room in which approximately sixty men were receiving chlorine treatment.6 The numbers in the “time” columns show the times expressed in number of minutes after the beginning of the hour, during which the samples were withdrawn from the room. Simultaneous runs by the o-tolidine and the iodometric methods are shown side by side. I n each case the o-tolidine solutions were diluted to 50 cc. and compared in Nessler tubes with the standards, the value for each determination being shown in the fourth column. It was found 8
Hale, I n d . Eng. Chem., News Edition, March 10, 1926, p. 3.
731
Concn. of c1 Mg./liter 0.008 0.0122 0.0096 0.0049 0.0058
impossible to get sharp end points in the titration of the iodine with the 0.001 N thiosulfate, and the values obtained for the very small concentrations of chlorine tend to be greater than those obtained by the o-tolidine method. It will be noted that the agreement between the two methods is closer in Table 11,where the amounts of chlorine are greater, and where the tendency to overrun the end point in the titration is consequently diminished. Summary
The o-tolidine method for estimating free chlorine in water has been satisfactorily applied to the determination of chlorine in air. The proposed method is quicker to run than is the iodometric method on account of the smaller volume of air sample that is required for each run. Some results checking the proposed method against the standard iodometric method are given.
Distribution of Sulfur in Oil Shale’ By E. P. Harding and William Thordarson UNIVERSITY
OF
MINNESOTA, MINNEAPOLIS, MI“.
HE purpose of this investigation was to determine,
T
if possible, the forms in which sulfur exists in an important oil shale of the Green River formation. Sulfur compounds2 in shale oil make its refining more difficult and costly and in some cases necessitate a rejection of the oil for refining and even for fuel purposes. Practically all oil shales yield hydrogen sulfide upon distillation, some large quantities. This gas is dangerous if present in sufficiently large concentrations, and it may sometimes be necessary to guard against its possible effect upon the plant, workers. Mineral lubricating oils which contain large percentages of sulfur compounds are generally more easily oxidized3 than those in which there is less sulfur, and are apt to form emulsions more readily than those containing less sulfur. Very little of all the research done on oil shale has been directed toward obtaining a low-sulfur oil by attempting to keep the sulfur out of the oil during the pyrolysis of the pyrobitumen or during the pyro decomposition of the bitumen formed. Some investigations have been carried out in which gypsum4 was added to the crushed shale. This had the same effect as adding steam equivalent to the water of hydration of gypsum used. At the Illellon Institute aluminum chloride4 was added to the shale before retorting. This material sublimed in the top of the retort, causing the oils t o polymerize and to stop up the outlets of the retort chamber. 1
Received January 30, 1926. Mines, Bull. 910 (1922). THIS JOURNAL, 14, 725 (1922). Chem. Met. Eng., 26, 546 (1922).
* Bur. 8 4
I n England work has been done on the effect of iron and iron salts added directly to the shalee4 None of these investigations reported the effect of the added material on the sulfur content of the oil or gas. The writers believe that sulfur in the oil shale could be kept out of the oil at a less cost during its formation than during the subsequent refining of the oil, and that hydrocarbons now lost in the heavy sulfuric acid treatment of the oil, as well as much sulfuric acid, might be saved. If such a removal of sulfur is ever attempted, a knowledge of the forms in which it exists in the shale and distillation products may be of value and, furthermore, may furnish a little more light on the origin of the kerogen. Sampling of Shale
A representative sample of oil shale was obtained from the Mount Logan Oil Shale LMining and Refining Company a t De Beque, Colorado. The sample was carefully reduced to 10-mesh size for retorting studies and a portion further reduced in an agate mortar to 80-mesh for chemical analyses. Total Sulfur in Raw Shale
The total sulfur determination was first attempted by the sodium peroxide fusion method, but check results could not be obtained. Blank determinations on the sodium peroxide showed comparatively large quantities of sulfur which varied in the different determinations; also varying amounts of nickel from the crucibles used mere occluded in the barium sulfate.
.
INDUSTRIAL A N D ELVGINEERING CHEMISTRY
732
Eschka's method was then tried, but difficulty was experienced in filtering the dissolved leached residue and because of the iron compounds occluded by the precipitated barium sulfate. A modification of Eschka's method, however, gave excellent results. One gram of shale mixed with 4 grams of Eschka's mixture and this mixture covered with another gram of Eschka's mixture was ignited in an electric muffle furnace. The ignited residue was thoroughly leached with hot water and the dissolved leached residue evaporated to dryness on a hot plate. This residue was dissolved in hydrochloric acid, again evaporated to dryness, then taken up with very dilute hydrochloric acid, and filtered. The iron in the filtrate was removed by pouring the filtrate into an excess of ammonium hydroxide and stirring, and the filtrate from this precipitate was treated separately for sulfur by the usual Eschka's method, as was the original filtrate from the ignited residue. ,4 blank determination for sulfur on 5 grams of Eschka's mixture was carried out in the same way as on the shale sample. The total per cent minus the per cent in blank gives the per cent sulfur in the shale. The following average results were obtained: Per cent 1.398 0.0245 1.373
Total sulfur Blank Sulfur in shale
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Different Forms of Sulfur in Oil Shale
,4s oil shale is composed of a pyrobitumen kerogen and mineral matter and as the line between coal and shale has never been sharply drawn,6 it was presumed that the same forms of sulfur might be present in shale as were found by Parr and Powell6 in their work on coals-namely, sulfate sulfur, sulfide sulfur, humus sulfur, and phenol-soluble or resinic sulfur. The methods of analyses used in this paper are in principle those used by Parr and Powell. Sulfate Sulfur
About 5 grams of SO-mesh shale were treated in a 600-cc. beaker with 300 cc. of 3 per cent hydrochloric acid. The mixture was thoroughly stirred, the beaker covered and placed on a well-regulated water bath for 40 hours at 60" C., with frequent stirring of the mixture. At the end of this period the solution was filtered and the residue thoroughly washed with water. Two cubic centimeters of saturated bromine water were added and the excess bromine was boiled off. The ferric hydroxide was then precipitated by pouring the hot solution into an excess of ammonium hydroxide and stirring to coagulate the precipitate. The ferric hydroxide was filtered off and the iron determined by the ZimmermanRheinhardt potassium permanganate titration method. Sulfur was determined in the filtrate by the usual barium sulfate method. The following average results were obtained: Sulfur Iron
Per cent 0.0865 0.56
Sulfide Sulfur
About 1 gram of the shale was covered with 80 cc. of cold dilute nitric acid (1 part of HN03, sp. gr. 1.42, to 3 parts H20). The solution was allowed to stand for a certain number of days with occasional stirring during the digestion period. The residue was filtered and well washed. Two cubic centimeters of concentrated hydrochloric acid were added to the filtrate, which was then evaporated to dryness. The residue was dissolved in 5 cc. of concentrated hydrochloric 6
8
U. S. Ccol. Surocy, B d t . 869, 11 (1918). University of Illinois Expt. Sta., Bull. 111 (1919).
Vol. 18, Xo. 7
acid, the solution diluted to 30 cc. with distilled water, and the iron precipitated by pouring the solution into an excess of hot ammonium hydroxide. The iron was determined in the precipitate as above by the Zimmerman-Rheinhardt titration method, and the sulfur in the filtrate by the usual barium sulfate method. The following results were obtained: Time of digestion Days 6 12 3
Mean per cent sulfur 0.732 0,828
0.724
Mean per cent iron 1.34 1.42 1.12
These results show that when the extraction is carried out longer than 72 hours iron other than hydrochloric acidsoluble and sulfide iron is dissolved and that some organic sulfur is probably attacked.' The discrepancy between the sum of the sulfate and sulfide sulfur in the 3- and 6-dag extractions is not appreciable. The difference between the per cent of nitric acid-soluble iron in the 3- and 12-day digestions may be accounted fors by assuming that insoluble silicates and aluminates are taken into solution in the longer extractions. From such a consideration it is obvious that the results obtained from the 3-day extractions should be used in establishing the iron-sulfur ratio. That sulfur in the sulfide form is contained in the shale as pyrites or marcasite, or both, is evident from the following consideration: The extraction with dilute nitric acid takes out the sulfate and sulfide sulfur and the hydrochloric acidsoluble iron plus sulfide iron. The sulfide sulfur is obtained by subtracting the sulfate sulfur from the nitric acid-soluble sulfur and the sulfide iron by subtracting the hydrochloric acid-soluble iron from the nitric acid-soluble iron. Sulfate and sulfide iron Sulfate iron
Per cent 1.12 0.56
0.56
Sulfide iron
Sulfate and sulfide sulfur Sulfate sulfur Sulfide sulfur
Per cent 0.7240 0.0865
0.6375
2s 64 - or 0.56 X = 0.642 per cent Fe 55.84 0.6420 - 0.6375 = 0.0045 per cent 0.56 X
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This 0.0045 per cent sulfur is the deficiency in sulfur content required to give the Fe:2S ratio. This discrepancy is within experimental error. Phenol-Soluble or Resinic Sulfur
An indirect method6 was used in determining the phenolsoluble or resinic sulfur. The shale was treated with phenol and the sulfur in the residue determined, which subtracted from the total sulfur in the shale gives the resinic sulfur. One gram of 100-mesh shale was extracted with 25 cc. of molten phenol in an Erlenmeyer flask at 145" C. for 20 hours in an oil bath. The flask had a ground-glass mouth and was provided with a ground-glass condenser. The flask was immersed to the top of its neck in the oil bath. At the end of the 20-hour period the flask was removed, washed free from the bath oil with carbon tetrachloride, and the contents immediately filtered by suction through a Gooch crucible containing a thin mat of fibrous asbestos. All the shale particles were transferred to the filter with 95 per cent alcohol and washed with alcohol until free from phenol, then washed with ether and dried a t room temperature. The shale residue with filtering mat was intimately mixed by means of a spatula (the fiber in the mat being well separated) with 4 grams of Eschka's mixture and the mixture covered with a fifth gram and ignited in an electric muffle. The sulfur in the ignited 7 Bur. Mines. Tech. P a f i n 964, 19 (1921). a r b i d . , p. 17.
INDUSTRIAL AND ENGINEERING CHEMISTRY
July, 1926
residue was then determined as previously given under the determination of total sulfur. The following average results were obtained : Per cent. 1.373 1.368
Total sulfur Sulfur in extracted shale Resinic sulfur
Per cent 0.649 0.005
Humus sulfur
0.644
Sulfur in shale Sulfate sulfur Sulfide sulfur Sulfur in phenol-extracted shale Organic sulfur
Organic and Humus Sulfur The difference between the total sulfur in the shale and the inorganic sulfur is organic sulfur.
Organic sulfur
Organic sulfur Resinic sulfur
Summary of Distribution of Sulfur in Oil Shale
0.005
Total sulfur Inorganic sulfur (sulfate-ksulfide)
733
Per cent 1.373 0.724
__ 0.649
The humus sulfur is the difference between the total organic sulfur and the phenol-soluble or resinic sulfur.
Per cent 1.373 0.0865 0.6375 1.368 0.649
Humus sulfur Resinic sulfur Sulfide iron Sulfate sulfide iron Sulfate iron
Per cent 0 644 0.005 0.56 1.12 0.56
Conclusion Sulfur is present in the form of sulfide, sulfate, and organic sulfur. The resinic sulfur found in those oils analyzed for resinic sulfur6 exists in quantities ranging from one-fourth to all the organic sulfur. The resinic sulfur found in the Mount Logan oil shale is so small in amount as to appear within the limits of experimental error and may be considered as practically absent in this shale.
Systematic Refining of Cracked Distillates' Chemical Factors in Refining By Jacque C. Morrell RESEARCH LABORATORIES, UNIVERSAL OIL PRODUCTS Co., CHICAGO, ILL.
HE development of cracking in the oil industry has T been such t h a t today i t is the greatest single factor in motor fuel production. I t is unquestioned that in the
near future the largest proportion of motor fuel produced will be of the cracked type. Further, it is believed t h a t in the more distant future, when the supply of petroleum is less plentiful, cracking will dominate all other methods for producing motor fuels. Shale oils, low-temperature coal tars, lignite, peat, and wood tars will all contribute their quota of motor fuel through the medium of cracking, and the chemistry of each type of cracked product m u s t be recognized in working out practical refining methods for the motor fuel produced therefrom. The chemistry of cracked distillates is much more complex than the chemistry of straight-run distillates. The advance of the cracking a r t has made necessary a n
advance in the a r t of refining cracked products. I t is the purpose of the present work to systematize the refining of cracked distillates based upon a study of the chemical factors involved and upon their application t o refining practice. I n addition to showing a definite order of procedure in the use of the simple refining agents, sulfuric acid, sodium hydroxide, and litharge, for each class of cracked distillates, the reasons for such procedure and a discussion of the reactions involvdhave been included. The chemistry of the distillation-step in the refining of cracked distillates, which was practically nonexistent in the refining of straight-run distillates, has also been discussed. All the methods described have been thoroughly tested out in plant practice by the writer.
. . . . . . ....... .
T
HE present minimum commercial criteria to be met
in the production of refined motor fuels are the absence of color, sweet odor, and stability under marketing conditions. The last refers to the development of color, cloud, or odor during storage or handling. In addition, they are usually required to meet certain conventional specifications such as those laid down by the Bureau of Mines.2 Further specifications may be prescribed by individual purchasers, principally dependent upon needs and customs. For example, the doctor test3 is sometimes required, although it is a t best only qualitative in showing the presence of hydrogen sulfide or the mercaptans; for other sulfur compounds or as a positive index of color stability it is meaningless. The various tests to which motor fuels are submitted, although in some cases bearing upon their utility, should be further investigated to put this relationship upon a more rational basis. This is especially demanded by the wideP a r t of paper presented before the joint session of the Divisions of Petroleum Chemistry and Gas and Fuel Chemistry a t the 70th Meeting of the American Chemical Society, Los Angeles, Calif., August 3 to 8 , 1925. 2 Tech. Paficr SPS-A, 3 (1924). I Ibid., p. 85. 1
spread use of the cracking process in the production of gasoline from all types of heavy oils and hydrocarbons from various sources. For example, no one has yet shown the relation between the percentage of combined sulfur and the tolerance of a gasoline motor and its feed system. Likewise, the present method of determining gum content is not a measure of gums in the gasoline, but is rather a measure of the gummy substances formed by the arbitrary method of determining them. To fix arbitrary limits upon unknowns does not appear rational. Certainly, a thorough study of the fundamental requirements of a motor fuel from a chemical as well as physical viewpoint, directed towards automotive utility, and a system of specifications based only upon these requirements will be of great value to the refining industry. Treating Methods and Reactions &me of the methods described have been previously mentioned.4 Their application is explained here in greater detail, however, which permits a more comprehensive understanding of their use. 4
Chcm. Me;. Eng., SO, 785 (1924).
