May 1950
INDUSTRIAL AND ENGINEERING CHEMISTRY DISCUSSION
The foregoing data show that as good or better detergent action may be obtained in many cases for a variety of soils by replacing pmt of the relatively expensive synthetic detergent by an inexpensive alkaline builder. Silicates and tetrasodium pyrophosphate are preferred to sodium carbonate, largely because of their ability to prevent the deposition or redeposition of soils on cloth. Most economical results can probably be obtained with mixtures of synthetic detergent, pyrophosphate, a sodium silicate, and some sodium carbonate. Such a mixture should contain the most efficient detergent for any one of the wide variety of soils found in practical applications. The effectiveness of such mixtures is frequently greater than expected on the basis of the efficiency of each constituent taken separately. In the present work this synergistic effect is most clearly demonstrated in the much greater increase in reflectance of the Testfabric's soiled cloth and lower decrease in brightness of the unsoiled portion after washing in mixtures of synthetic detergent with pyrophosphate or metaor sesquisilicate than after washing in either alone. Perhaps part of the synergism is due to one or more of the soil constituents being preferably removed by one component of the mixture. Such an explanation is in agreement with the greater complexity of the soiling mixture showing the largest synergistic effects but probably does not explain all cases of synergism in detergent studies. An important result of this work is the demonstration that the relative effectiveness of the synthetic detergent and builders varies with the type of soil. Thus, the dodecyl benzene sodium sulfonate was the best suspending agent for iron oxide, poorer than the pyrophosphate or silicates but better than sodium carboriate or hydroxide a t most concentrations for ilmenite, and al-
861
most the poorest for raw umber. The relative order of efficiency of soil removal by mixtures containing up to 50% of 3 silicates and pyrophosphate for the U. 8. Testing Company's soiled fabric was almost the inverse of that obtained with the Testfabrics Inc. cloth. A mixture of equal weights of synthetic detergent and sodium metasilicate removed definitely less soil from the cloth obtained from the U. S. Testing Company than did the detergent alone. The same mixture removed about the same amount of soil from the cloth soiled with the Pennsylvania State College mixture as did the detergent by itself, but removed considerably more soil from the soiled cloth obtained from Testfabrics Inc. The best detergent for a particular application varies with the type of soil. Results based on only one type of soil can be misleading. For practical studies the soil and testing technique used for evaluating detergent mixtures should closely approximate the conditions under which the product is to be used. LITERATURE CITED
(1) Carter, J. D.,IND. ENG.CHEM.,23, 1389 (1931). (2) Carter, J. D., and Stericker, W., Zba'd., 26, 277 (1934). (3) Dreger, E. E., Keim, G. I., Miles, G. D., Shedlovsky, Leo, arid Ross, John, Ibid., 36,610 (1944). (4) Harris, J. C.,OiE & Soup, 23, 101 (1946). (5) Harris, J. C.,Soap Sanit. Chemicals, 19, 21 (1943); A.S.T.M. Bull. 125, 27 (1943). (6) Harris, J. C., and Brown, E. L., Oil & Soap, 22,1 (1945). (7) Morrisroe, J. J., and Newhall, R. G., IND.ENG.CHEM.,41,423 (1949). ( 8 ) Palmer, R. C., J. SOC.Chem. I n d . , 60,56 (1941). (9) Powney, J., and Noad, R. W., J . Textile Inst., 30,TI57 (1939). (10)Vaughn, T.H., and Smith, C. E., J. Am. Oil Chemists Soc., 25, 44 (1948). RECEIVED September 29, 1949.
Hydrogenation of Coal in a
Fluidized Bed E. L. CLARK, M. G. PELIPETZ, H. €1. STORCH, SOL WELLER, AND STANLEY SCHREIBER Central Experiment Station, U.S. Bureau of Mines, Pittsburgh, Pa. Undesirable features of the Bergius-I.G. process, which include difficult handling of a residue-oil slurry, reaction space used for recycle oil, and deleterious effect of recycle oil on hydrogenation of coal, suggest the desirability of developing a dry-coal hydrogenation process. Bench-scale hydrogenation tests of a Wyoming bituminous coal in an agitated or fluidized bed produce oil yields of 20 to 27Yo and hydrocarbon gas yields of 20 to 279$ of moisture- and ash-free coal at hydrogen pressures of 1000 pounds per square inch and less. Hydrogenation of coal using a fluidized coal bed thus offers a possible means of dry coal processing at pressures well below those used in European plants. Products of the fluidized bed hydrogenation are oil, hydrocarbon gases, and a char residue suitable for use as fuel or feed for gas production.
G
ERMAN practices in the high-pressure hydrogenation of coal by the Bergius-I.G. process have been disclosed by many published accounts. These German hydrogenation plants, produced the bulk of the aviation fuel and part of the motor gasoline, Diesel fuel, fuel oil, paraffin wax, and lubricating oil
required by the German war machine (6). Many features of this Bergius-I.G. process indicate potential advantages in effecting,a reaction between dry coal and hydrogen: The equipment required to condition heavy oil-let-down for use as a pasting or injection oil with coal feed could be eliminated. Reaction space used by the oil portion of the coal-oil feed mixture could be used for the reaction of additional coal. The removal of unreacted coal as a dry material instead of a mixture with oil would materially decrease the capital and maintenance cost of the hydrogenation plant. I n addition, work in batch autoclaves where coal was hydrogenated in both the presence and absence of a heavy oil vehicle indicated that the heavy oil exercises a deleterious effect on the reaction ( 7 ) . Unpublished data obtained in batch autoclaves by Donath indicated the possibility of obtaining good liquid yields a t moderate pressures with dry coal ( I ) . The experimental work presented herein represents a possible means of carrying out the hydrogenation of dry coal. Additional experimentation is in progress, and the data presented here are being expanded to cover additional coals and to investigate other problems leading to the development of a usable dry-coal hydrogenation process.
Vol. 42, No. 5 Handling of the reaction products is simplified by the use of liners in both the reactor and cold trap. A stainless steel liner permits easy removal of the residue remaining in the reactor (this liner proved unnecessary, as no agglomeration of residue was noted with Rock Springs coal). A sample of the residue is used for an ultimate analysis. A glass liner in the cold trap is designed to permit connection of a v a c u u m train. The liquid products are stripped a t 1 to 2 mm. of mercury (absolute pressure) while !he liner contents are maintained at 100” C. to remove n a t e r and light oil. The water and light oil are weighed, and the amount of heavy oil product is obtained by subtracting the sum of water and light oil obtained in the vacuum stripping operation from the weight of the total product obtained from the rold trap. Samples of light oil and heavy oil are bubmitted to an ultimate analysis. The heavy oil Figure 1. Unit for Fluidized Hydrogenation of Coal is dissolved in benzene to determine its insoluble EXPERIMEYTAL UNIT AND PROCEDURE content. The insolubles (usually less than 0.5 gram) are includcd with the reactor residue. -4 sample of heavy oil is The equipment is shown diagrainmatically in Figure 1. anaij.eed for asphalt, where ‘.asphalt” is considered to he t,he material soluble in benzene and insoluble in n-hexane. Gas samples are taken at %minute intervals during the heating, Hydrogen gas is fed from a bank of cylinders through a hantireaction, and cooling periods. These samples are analyzed by a throttling valve into the preheater, a coil of ‘/r-inch outside mass Apectrometer and the values obtained for eac$hcomponent diameter and l/rinch inside diameter stainless steel (Type 347) are plotted against time, The curves obtained are integrated tubing embedded in an electrically heated aluminum block. by rveighing the encalosed area of paper, and
