Silica Black C. A. JACOBSON,West Yirginia University, Morgantown, W. 1-a. For the distillations a 1-quart ONFORMISG t o t he Silica black is made by mixing together jinely (0.95-liter) capacity iron retort, recently adopted policy divided coal and siliceous material such as diatowith a goose-neck iron delivery of this university of appipe, was used. Into the crucible mite, and the mixture heated in the absence of air plying the facilities of the state's cover was inserted a 4inch (10.2to between 650" and 1100" C. The resulting cm.) iron thimble which served largest educational institution to to hold the thermocouple of the powder is air-floated and separated into three the development of the natural pyrometer in the middle of the resources of the state, the effect grades; the jinest has a gravity of 0.25 and is retort during the distillations. of heat upon mixtures of finely The heating was accomplished composed of about 18 per cent carbon, 75.5 per divided bituminous coal and siliby means of a large-size Hoskins cent silica, and 6.5 per cent oxides, sulfides, and electric crucible furnace for 110ceous materials is studied. volt c u r r e n t . This was placed silicides of iron, aluminum, etc. A pure grade of almost white in a wooden box and covered Silica black has a high oil absorption, mixes diatomite from Roderick, with asbestos boards, a 1low i n g Nev., was available in considerspace only for the exit pipe and well, and has good spreading quality; it therefore pyrometer wires. The d e l i v e r y able quantity a n d t h e r e f o r e might be used as a pigment in paints, printing pipe from the retort was threaded w a s m o s t extensively used in into the cover of an iron cylininks, etc. I t reduces metallic oxides at high temt h e experiments. B o t h t h e der, which was surrounded with peratures. I t adheres tenaciously to objects and precipitated silica and the silicic cold water and served as the tar trap and also for the condensamight be used as a carrier for insecticides, wood a c i d c a r r y i n g 38.5 per cent tion of most of the water. The w a t e r were Baker's Analyzed graining, leather tinting, etc. It might be used exit p i p e of t h e t a r t r a p w a s c . P. products. The talc used connected with a gas wash bottle as a support f o r nickel in various hydrogenation was the f i n e s t g r a d e of t h e containing concentrated sulfuric processes. acid, and t h i s in t u r n with a W. H. Loomis Talc Corporation safety bottle and condenser for Smoke belching from stacks is probably largely of Gouverneur, N. Y., 99.5 per h e a v y hydrocarhons. The last silica black. cent of w h i c h p a s s e d a 325bottle connected directly to a wet mesh screen. The d i a t o m i t e gas meter where the volume of was ground and &floated before using, but the other prod- the gas obtained in each distillation was measured. From the gas meter the gas was conducted into a storage gasometer for ucts were not. analysis. The same lot of bituminous coal was used in all experiments A new &skins electric pyrometer,recording temperatures in here recorded and was obtained from the Davis and Rey- degrees Centigrade, was used. This instrument was restandardnolds mine near Morgantown. This is a good coking coal ized with sulfur at the boiling point. The gas was analyzed by Henry S. Hopkins in the improved-model gas analysis apparatus of the Pittsburgh vein, which was ground and air-floated of the U. S. Bureau of Mines. The clarification experiments were before mixing with the siliceous materials. The screening performed by the Duboscq colorimeter. test of the B-aade coal used for the distillations gave: 49.58 MIXTURESDISTILLED per cent thriugh 200-mesh, 18.38 per cent (plus the first 49.58 per Preliminary experiments w e r e cent) through 100-mesh, and 32.04 performed in which equal weights of c o a l a n d d i a t o m i t e w e r e per cent r e m a i n e d o n 100-mesh thoroughly mixed in a pebble mill, screen. The diatomite used was and 200 grams of the mixture were finer than the coal, but no screening heated for 4 hours to the maximum test was made of it. attainable t e m p e r a t u r e (about EQUIPMENT 1100" C.) w i t h the e q u i p m e n t mentioned. About 20 liters of a A coking coal possesses aggluticombustible gas were collected in nating properties, and, when such coals in finely divided condition are the gasometer, and 160 grams of a black pulverulent product left in mixed with fine sand (40- to 50the retort. Without grinding, 43 mesh) and subjected to destructive per cent of this crude black proddistillation, hard products are obuct p a s s e d t h r o u g h a 200-mesh tained. To avoid this it was necesscreen and the major portion of the sary to have the siliceous material remainder through 100-mesh. The in an extremely fine state of divicrude black product analyzed about sion; this was accomplished by first 40 per cent carbon, 53.5 silica, and grinding the diatomite in an A. W. 6.5 nonsiliceous inorganic material. S t r a u b m i l l a n d air-floating the This black powder could not be product by means of the two air separated into dark and light coms e p a r a t o r s s h o w n in Figure 1. ponents like the original products This air classification resulted in a by employing either air, water, or finer and a coarser product, A and oil flotation. Neither could white B, r e s p e c t i v e l y . Not only the or gray particles be r e c o g n i z e d d i a t o m i t e and the coal were so u n d e r a m a g n i f i c a t i o n of 560 separated, but also the final disdiameters. tillation product. FIGURE1. AIR SEPARATOR
C
798
I N D IJ S T R I A L A N D E N G I N E E R I N G
July, 1934
The mixture of coal and diatomite had changed into something that was no longer a mechanical mixture. This product the author called “silica black.” More than thirty distillations of mixtures of carbonaceous materials such as coal, wood flour, beet pulp, and molasses, with siliceous materials such as diatomite, fuller’s earth, precipitated and dried silica, silicic acid, and talc have been carried out. An attempt was made to mix these in such proportions that the silica and carbon would be present in equivalent quantities. Table I contains the records of the distillations of three different mixtures, as well as the distillation of coal alone under two sets of conditions. The first four runs with coal showed that, at the end of 3 hours of heating, the same temperature had been reached but that the evolution of gas was far from complete. I n the next three runs with coal the heating was continued for 4 hours, showing a variation in temperatures due perhaps to the difference in packing or the initial temperature of the furnace. However, it was decided to keep the heat unit as well as the time constant and allow the temperature and the gas yield to be the variables. The gas that came over a t the end of 4 hours of heating was negligible. Column 5 gives the averages of gas yield in the five sets of distillations. TABLE I. DISTILLATION DATA SUBSTANCEDISTILLED
ItCN
HEAT1x0
TEYP.TIME
c.
5 6 7
100 g . coal Same Same Same
590 590 590 590
Hours 3 3 3 3
Same Same Same
680 690 700
4 4 4
670 648 648 655
4 4 4 4
8 9 10 11
100 g . coal Same Same Same
12 13 14
100 g. coal Same Same
15 16 17
100 g. coal Same Same
+ 106.4 g. diatomite + 100 g. ignited diatomite
+ 138.5 g . silicic acid
635 660 650 690 675 688
C O R . Gas
YIELD Liters 15.22 15.16 15.07 14.97 Av. 15.11 17.72 17.90 18.12 Av. 1 7 . 9 1 20.26 20.39 20.53 20.47 Av. 20.41 18.82 18.91 18.93 Av. 1 8 . 8 9 24.45 24.43 24.74 Av. 2 4 . 5 4
Table I1 gives the analyses of all three grades of silica black obtained by mixing coal with the different siliceous materials specified in column 3. Except in runs 3, 7, 9, and 12 the temperatures given are those recorded when the thermocouple was placed in the iron thimble as explained. The lot listed under sample 2 was made in a 25-gallon (or larger) retort by the Penn-Rillton Company, where the thermocouple was placed a t least a foot down in the mixture. Lot 7 was made in a (No. 10) lava crucible heated in a large gas-air crucible furnace a t a temperature of approximately 1100” c. TABLE 11. LOT
GRADEOF SILICA BLACK
SOURCEOF SILICABLACK
Crude Crude Crude Crude A A A A B
13 C
c
BA BB
Crude
Coal and diatomite (680° C.) Same (98Z0 C.) Wood flour and diatomite Coal and talc Coal and diatomite (6R0° C.) Same (680’ C.) Same (1100O C.) Coal and pptd. Si02 Coal and diatomite ( l l O O o C.) Coal and pptd. Si02 Coal and pptd. Si02 Coal and diatomite (1100’ C.) Grade B (No. 9) reground Same Lignite and diatomite
TABLE 111. GAS ANALYSES 100 g. coal 100 g . coal 100 g . coal 106.4 g. 106.4 g. 106.4 g. 100 g. coal 100 g. coal diatomite diatomite diatomite f 159.6 g . 270g. f log. 2Og. 4- 30 g. COMPONENTS diatomite talc water water water
+
0.2268 0.8241 0.2510 0.2510 0.3280 0.2201 0.7085 0.6657 0,6328 0.6248 0,3012 0.7197 0.3903
%
%
%
+
%
%
COMPOSITION OF SILICABLACK This product, when made from coal and diatomite, or coal and precipitated silica, is a black siliceous material containing carbon in different proportions together with 4 to 7 per cent of a nonsiliceous residue composed mainly of iron and aluminum. When the silica black is obtained from coal and talc, however, the nonsiliceous residue amounts to more than 38 per cent. X-ray photographs indicate that silica black is principally amorphous. However, a trace of a silicon carbide pattern is visible, showing that a small amount of crystalline silicon carbide must be present. The greater part of the carbon in the product is doubtless in the adsorbed form, although a certain proportion may be represented as carbides of silicon, iron, and aluminum. Considerable difference is shown in the composition as well as specific gravity of the A and B grades. It is interesting to note that the A grade is considerably darker in color than the B grade although its carbon content is less than half that of the latter. The nonsiliceous residue from all three grades made from diatomite and coal contained iron, aluminum, magnesium, and calcium together with small amounts of phosphorus, sulfur, and sodium. One lot of the B grade yielded 1.80 per cent iron calculated as ferric oxide. PROPERTIES OF SILICABLACK Silica black is insoluble in water and the ordinary organic solvents; 1.88 per cent of the A grade (from diatomite) dissolves in hot 10 per cent hydrochloric acid, indicating that over 50 per cent of the nonsiliceous inorganic constituents are present either in the form of carbides or insoluble silicates. The former assumption is doubtless the more probable. SILICA BLACK
APPARENT SP. GR. STATE
....
+ +
+,
ANALYSES O F
0.4744
799
Table I11 contains five of the thirteen analyses of gases. Columns 2 and 3 show that, when the gas is obtained from coal in the presence of a large excess of diatomite, as well as talc, the percentage of hydrogen and carbon monoxide are lower than when the same kind and quantity of coal is distilled with diatomite plus increasing amounts of water. Unfortunately the data, obtained from the gas when coal alone was distilled, were lost. They did not vary greatly from those in columns 2 and 3, however.
Av. No. OF
% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
CHEM ISTR Y
43
.... 100 84.39
DIVISION
Mesh 200
... ... ...
200 100
C
% 39.79 41.61 37.57 27.81 18.53 18.14 17.27 17.34 47.93 31.07 50.12 48.45 25.60 59.13 25.99
OF
&Or
%
R K U I D U ~ANALYSES ~ %
53.90 6.47 50.94 7.53 58.00 4.43 34.15 38.04 (Liehig C ombustion) 75.56 6.25 75.65 7.08 75.33 7.29 45.52 6.54 64.46 4.46 44.70 5.18 44.56 6.99 67.96 6.47 34.23 6.64 58.79 15.46
2 2 2 2 2 2
3
3 2 2 2 2 4 4 2
800
INDUSTRIAL AND ENGINEERING
L. R. Williams has shown that grade-A silica black is superior to the above mentioned diatomite as a carrier for nickel in the hydrogenation of cottonseed oil. A detailed discussion of this property of silica black will appear in a later paper. The apparent specific gravities (Table 11) were obtained by weighing the products dry in air after uniform tapping and dividing these weights by the weight of the same volume of water. The true specific gravities of some of the lots listed in Table I1 are as follows: A from lot 2, 1.830; lot 7, 1.954; lot 8, 2.195; lot 9, 1.881; lot 12, 1.902. These values are the averages of two or more determinations using kerosene and an oil vacuum pump. An attempt to use silica black for the purpose of clarifying and decolorizing a dark corn sirup was made by John F. Rush with the following results: 25 grams of the sirup were diluted with 25 cc. of water plus 5 grams of silica black for each experiment. The mixture was stirred and heated to boiling and again stirred for 5 minutes. After filtering through filter paper, the solutions mere compared in a Duboscq colorimeter with that obtained from animal charcoal using a 10-mm. layer as standard. BA lot 13 (Table 11) gave 7.0; lot 3 , 12.8: lot 9, 9.2; lot I , 16.6; and grade 1 (lot 5), 18.6; animal charcoal, 10. For this particular sirup, grade-A silica black is nearly twice as efficient as animal charcoal. When Jack Frost brown sugar solutions were used, the color comparisons were not as good although the clarification was perfect. M. M. Brown has investigated the reducing property of silica black a t different temperatures. He found that metallic lead, bismuth, and antimony resulted when mixtures of their oxides with silica black, contained in clay crucibles, were heated to approximately 650' C. I n one experiment bismuth trioxide was fused and small amounts of silica black added from time to time, resulting in a metallic button of bismuth at the bottom of the crucible. A charge of 75 grams of litharge was similarly reduced, yielding a lead button weighing 32 grams. A mixture composed of equal weights of ferric oxide and grade-A silica black, plus 10 per cent lime, was heated in an arc furnace for half an hour, yielding a metallic button
CHEMISTRY
Vol. 26, No. 7
analyzing 92.6 per cent iron and 7.2 per cent silica. It was very hard and brittle. A glassy black flux surrounded the button. A mixture of chromite ore, ferric oxide, and silica black in the ratio of 3:15:16, respectively, was submitted to J. Goebel and Company of S e w York for fusion in their Degoussa high-temperature furnace. They added a small amount of flux but no other reducing agent, and returned not only the metallic button but part of the clay crucible which contained a black glassy flux about 0.25 inch (0.635 cm.) thick. The alloy of chromium and iron had a strong metallic luster. The experiments now in progress indicate that silica black might successfully be used as a carrier for insecticides, in acid- and rust-proof paint, for printing ink, for shoe blacking, and for stove polish. SIMILARPRODUCTS A search of the chemical literature has revealed nothing of the same nature as silica black. Repeated searches of the Cnited States Patent Office have been made by competent attorneys, with the result that three patents have been issued on somewhat similar products: Pfander ( 3 ) makes a substance by heating a mixture of clay, vegetable charcoal, and blood, which is suitable for filtering and decolorizing solutions. Gatehouse ( I ) claims a "silico-carbon suitable for use as a deodorizer, filtrant, and disinfectant," made by destructively distilling a mixture of siliceous material with granulated lignite. Hoodless ( 2 ) claims a decolorizing and filtering material made by soaking diatomite in molasses (blackstrap) and distilling the dried mixture without access to air. LITERATURE CITED (1) Gatehouse, J. W., British Patent 9102 (1884). (2) Hoodless, U. S. Patent 1,589,532 (1926). (3) Pfander, C. G., British Patent 2137 (1880).
RECEIVED September 23,
1933. Presented in preliminary form before the Division of Industrial and Engineering Chemistry at the 84th Meeting of the American Chemical Society, Denver, colo , August 22 t o 26, 1932
Silica Black as a Nickel Carrier in Oil Hydrogenation LORINGR. WILLIAMS AND C. A. JACOBSON, West Virginia University, Morgantown, W. Va.
T
HE vegetable oil industry was revolutionized in 1897 to 1905 by Sabatier and Senderens' discovery (9) that vegetable oils of little or no value could be converted into solid fats by saturating them with hydrogen. These experimenters used nickel as a catalyst but worked in the vapor phase. I n 1902 Leprince and Siveke (6)obtained a German patent on a process for hydrogenating vegetable oils in the liquid phase, using nickel as the catalyst. Since the resulting products were of great commercial value not only as edible fats but for the manufacture of hard soaps, the industry grew by leaps and bounds, and variations of the hydrogenation process were put on record in virtually every patent office in the world. The value of this industry can be approximated only roughly. Any improvement, however slight, in a process of such tremendous proportions as that of the hydrogenation industry would be of incalculable value. Consequently it was decided to compare the newly discovered silica black ( 5 ) with finely
divided diatomite as a carrier or support for the reduced nickel in the hydrogenation process. Sabatier (9) considered the catalytic action as being due to nickel in the reduced form; this view was also held by Norman (7), but Ipatiev (4), Erdmann @), and others (1) maintained that the oxides or suboxides of nickel are the effective catalysts or indispensable promoters of the catalyst. The previous paper ( 5 ) reported that silica black is a strong reducing agent, owing to adsorbed and, doubtless, activated carbon; it may throw considerable light on the question of whether reduced nickel or its oxides are the effective catalytic agents. Sabatier and Kelber ( 8 ) report that 300" C. must not he exceeded in preparing the catalyst, for under those conditions its activity diminishes, probably because of oxygen adsorption. However, when an inert carrier for the catalyst is employed, it may be heated to 500" C. without appreciably losing its activity. Under those conditions it is also less sensi-
