CATALYTIC DECORIPOSITION OF KEROSENE* BT E.
w,KAXSISG'
AND 0.
w.
BROWX?
Introduction Hydrocarbons, when subjected to rather high temperatures, decompose giving a wide variation of products. The hydrocarbon may decompose in such a manner to produce hydrocarbons lower in the series, unsaturated compounds, or hydrocarbons higher in the series. It is also possible that in the case of paraffin hydrocarbons, aromatic compounds result from the thermal decomposition. In most cases hydrogen and carbon are among the various products. The complete decomposition of any hydrocarbon would, of course, give hydrogen and carbon as the sole products. In the case of methane a rather high temperature is required for its complete decomposition. Methane starts to decompose a t 6 j 0 - 7 0 0 ~ C and . ~ has been found t o completely decompose in a porcelain tube a t 780-980"C.~ Since high temperature is necessary to bring about the decomposition of hydrocarbons, the use of catalysts has been studied to a great extent with the aim of lowering the temperature of decomposition and of studying the effect of catalysts on the products of the decomposition of various hydrocarbons. Use has been made of catalysts in the petroleum industry for the purpose of cracking the high-boiling fractions of petroleum to more valuable low boiling fractions. Much investigation in this particular field has resulted in the production of a larger total volume of gasoline from the same volume of crude petroleum. Schenck, Xrageloh, Eisenstecken and Klas5 have studied the decomposition of methane over iron and cobalt catalysts and have found that over iron, methane starts to decompose a t 3 j0"C. and a t 740°C. 89.6% decomposition was attained. Over cobalt, the decomposition began at 3 IoOC. and reached a maximum of 89.1j% a t 740°C. Sabatiers has reported the decomposition of methane starting a t 320' C. over a nickel catalyst. With paraffin hydrocarbons higher in the series, the initial decomposition temperature is lower. For example, ethane starts to decompose with the aid of catalysts at 48 j°C. and the decomposition is quite rapid at 7ooOC. The decomposition products become more complex also as hydrocarbons higher in the series are decomposed. 'This paper is constructed from a dissertation presented by Eugene William Kanning to the Faculty of the Graduate School of Indiana University in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry. 1 Instructor of Chemistry, Indiana University. 2 Professor of Chemistry, Indiana University. Egloff, Schaad and Lowry, Jr.: J. Phys. Chem., 34, 1623 (1930). Bone and Jerdan: Chem. News, 84, 7 (1901); Proc. Chem. SOC., 17, 164 (1901,. Schenck, Krdgeloh, Eisenstecken: Z. anorg. allgem. Chem., 164, 313-325; Schenck, Krjgeloh, Eisenstecken and Glas: 145-8j (1927); Stahl Eisen, 45, 671-67j (1926). Sabatier and Senderens: Ann. Chim. Phys., (8) 4, 435 ( 1 9 0 5 ) .
2690
E. W. KANSING AND 0. W. B R O W K
The effect of catalysts on the decomposition of hexadecane is reported by Gault and his co-workers.' In this work Gault studied the effect of temperature and catalysts on the properties of the products obtained. The volume of gas, volume of liquid, per cent saturated and unsaturated hydrocarbons, the density of the liquid and the composition of the gaseous products were noted. The results obtained point to many interesting facts. With an increase of temperature the volume of the gas, per cent hydrogen in the gas, per cent liquid below hexa-decane and the yield of unsaturated and aromatic hydrocarbons increased. The volume of t'he liquid products accordingly decreased with a rise in temperature. Gault and his eo-workers also found that the carbon deposited on the catalyst a t low temperature renders the catalyst less active, while that deposited a t higher temperature seems to have no effect on the catalyst. Of the most common catalysts which have been studied for the decomposition of hydrocarbons, cobalt, iron and nickel have probably been most successful in lowering the initial decomposition temperatures. The following investigetion was undertaken to determine the most suitable temperature for the decomposition of a fraction of kerosene which boils between zoo and 23oOC. when passed over cobalt, iron, manganese or nickel catalysts. The effect of change of temperature on the volume and composition of gaseous products was studied. The per cent of hydrogen, methane, higher paraffin hydrocarbons and unsaturated hydrocarbons was determined in the gaseous product obtained at different temperatures. The volume, density and iodine number of the liquid hydrocarbon produced was also determined. I n each instance the weight of carbon deposited on the catalyst from a given volume of kerosene was ascertained. K i t h the cobalt catalyst, the relation between the rate of flow of kerosene over the catalyst, and the volume and composition of the gas produced was studied. Apparatus The apparatus shown in the ske'tch, Fig. I , was used in all the experiments throughout this investigation. In Fig. I the capillary tube, E, is Felded to the glass tube, D, and is bent so as to extend into the iron pipe, F, about three inches. The junction between the iron pipe and the capillary tube is made gas tight by means of a small piece of heavy rubber tubing. The glass tube, D, having a volume of about I Z cubic centimeters, holds the liquid to be introduced into the reaction chamber and the rate of f l o of ~ this liquid is regulated by raising and lowering the mercury leveling tubes, A. The glass tube, D, and the mercury leveling tubes, A, were made from broken burettes and the graduations were found to be quite convenient in adjusting the mercury level and regulating the rate a t which the liquid mas passed through the capillary tube. 'Gault and Hemel: Compt. rend., 179, 171-173 (1924);Ann. Chim., ( I O ) 2, 318-377 (1924);Gault, Hessel and Altchidjian: Compt. rend., 178, 1562-5 (1924); Gault and Sigwait: Ann. combustibles liquides, 2, 309-323, j43-84 (1927).
CATALYTIC DECOMPOSITIOX OF KEROSENE
2691
FIG.I A-Mercury leveling tubes which furnish pressure for the introduction of liquid into the catalyst tube. B-Rubber tubing. C-Mercury. D-Glass tube into which the kerosene (B.P. 2oo0-23o0 C.) is placed; E-Capillary tube welded to D conveying the liquid into the catalytic furnace. F-Iron pipe M inch diameter, extending into the furnace to the catalyst tube; G-Gas weld. H-Iron pipe cap for 334 inch diameter iron pipe. I-Catalyst tube, iron pipe I W inch diameter and 1 8 inches long. J-Iron pipe cap for I % inch diameter pipe. K-Heating jacket, iron pipe 3% inch diameter and I j inches long. L-Single layer of asbestos paper. RI-Layer of alundum cement. S-Heating element. 0-Layer of alundum cement. P-Four layers of asbestos paper. &-Eutectic alloy of lead and tin. R-Cat alyst. S-Iron rings. T--Sickel gauze. U-Thermocouple well, iron pipe % inch diameter and j inches lone. V-Copper-advance (constantan) thermocouple. %-Iron pipe reducer, from 1 % inch to 34 inch. X-Iron pipe % inch diameter. Y-Water condenser. 2-Glass U tube with a glass tube welded to the bottom of the U, serving as a liquid trapi 1-2 j cubic centimeter graduated cylinder. n-Screw clamp. 3-Glass U tube. 4-Glass bottle, 8 liter capacity. j-Glass tubing. 6-Rubber stopper. 7-Water.
2692
E. TI’. KANNING AND 0.W. BROTVN
The mercury pressure necessary to allow the liquid to pass into the catalyst tube at a gradual and constant rate depends upon the size of the capillary tube used. The upper iron pipe cap, H, is screwed loosely to the heating jacket, K, and contains holes of the necessary size through which the catalyst tube, I, the iron pipe, F, and the thermocouple well, U,extend. These tubes are all gas welded to the iron cap. Therefore, when this upper cap is screwed on to the heating jacket, the three tubes are held securely in place. The lower pipe cap, H, is screwed t o the bottom of the heating jacket and is macle tight with a lute consisting of red lead, litharge, glycerine and water. This cap forms the bottom of the container of the molten lead-tin bath and must be made tight. The reaction tube, I, is an iron pipe 14 inches inside diameter and 18 inches long. This tube extends above the upper pipe cap about three inches and down into the molten bath, Q. The upper end of the catalyst tube is fitted with a pipe reducer, M-,which reduces a 13 inch diameter pipe to one of $ inch diameter. The lower end of the tube is fitted nith a pipe cap, J. Both the reducer and the cap are screwed to the iron tube and are made remorable to allow easy changing of the catalysts. They are made gas tight by means of the red lead-litharge-glycerine-water lute. The iron feed pipe, F, which extends down into the molten bath along side of the catalyst tube, is gas welded into a hole in the side of the catalyst chamber one inch from the lower extremity. The liquid entering the furnace through this feed pipe, F, is thus pre-heated to the temperature of the catalyst before it passes over the catalyst. The catalyst, column, R, is about I O inches long and is held in place by means of a round piece of nickel wire gauze, T, resting on two iron rings, S. These rings have an outside diameter of a little less than I$ inches so as to afford easy replacement in the catalyst tube which is 13 inches in diameter. The lower ring is held in place by the tube, F, which extends into the catalyst tube, I, about t inch. The nickel gauze and single iron ring above the column of catalyst are merely to keep the catalyst, in its given position while assembling the apparatus. The lower end of the catalyst column is one inch above the point at which the tube, F, enters the reaction chamber. The upper end of the catalyst tube, I, which is fitted with the reducer, K, extends one inch and then by means of an elbow bends a t right angles and extends four inches, where it is connected to the glass condenser, Y, by means of heavy rubber tubing. The heating jacket, K, is covered with a single layer of asbestos paper, L, which was securely cemented to it with sodium silicate solution. A coating of alundum cement mixed with water and about inch thick was placed over the asbestos layer. !Then the cement had dried, twenty-five feet of chrome1 wire No, 16, B and S gauge, N, Fig. I , was wound on top of this layer of alundum cement. In starting the winding of the wire, the end was doubled back about two feet and this doubled end was twisted securely around the jacket with about six inches of the end extending out for electrical connection.
a
CATALYTIC DECOMPOBITION OF KEROSENE
2693
This first round of wire does not do any of the heating but merely holds the rest of the coil in place while winding. When the coil of chromel wire has been wound to the other end of the heating jacket, the end is again doubled back. At this point, instead of continuing the winding in the same direction, the doubled wire is bent so as to wind it in the opposite direction. This forms a loop in the wire and the end is brought through this loop, bent back and twisted tightly with one side of the loop, the end extending several inches for electrical connection. This heating coil of chromel wire was covered with a layer of alundum cement, 0, which was about % inch thick. Over this layer of alundum cement were wrapped three or four layers of asbestos paper in order to insure heat insulation. The heating coil was connected to the I I O volt D.C. circuit and the heat regulated by means of an external chromel wire resistance. The temperature was measured by means of a copper-advance thermocouple described in a previous article from this laboratory.' The thermocouple extended into the molten bath of tin and !ead in the thermocouple well, U. The temperatures recorded in this investigation are correct within 2 - 5 degrees Centigrade. The molten bath, Q, of the eutectic alloy of tin and lead was found to be very suitable for the temperatures employed in the experiments conducted in this investigation. The glass water condenser, Y, fitted to the iron pipe, X, by means of rubber tubing, is welded to the U tube, Z. This U tube with a short glass tube welded to its lower part serves as a trap for the liquid products which drop into the graduated cylinder, I , while the gaseous products pass on into the gas-collecting apparatus. The glass U tube, 3, contained a small amount of water through which the gas bubbled. This indicated when the gas was passing into the collector. The screw clamps, 2, were clamped over short pieces of rubber tubing which permitted the removal of the gas collector for the collection of samples of gas for analysis, or for the exchange of gas collectors during the progress of an experiment. The gas-collecting apparatus consisted of two glass bottles of about eight liters capacity. The gas obtained as the product of the catalytic decomposition was collected and confined in one of these bottles while the other, which was fitted with an outlet in the bottom, was used only as a leveling bottle to keep the level of the water, over which the gas is collected, the same in the two bottles. The two bottles were connected as shown in the diagram, Fig. I , by means of a long rubber tube to allow the raising and lowering of the leveling bottles. Wherever stoppers were needed rubber stoppers were used in order to keep the apparatus gas tight. Care was taken in setting up the apparatus to insure a gas tight construction in order to exclude atmospheric gases from the interior and to keep the interior gas from escaping. The catalytic furnace was tilted about 2 5 ' from the vertical position in order to allow the water condenser to assume a slanting position. R. J. Hartman and 0. W. Brown: J. Phys. Chem., 34, 26j1-65(1930)
2694
E. W. XANNISG AND 0 . W. BROWN
Procedure Before each experiment was undertaken, the furnace was brought to the desired temperature while a stream of hydrogen was being passed through the catalyst tube at the rate of 14 liters per hour, thus preventing the oxidation of the catalyst. (Hydrogen was also passed over the catalyst while the furnace was cooling). The hydrogen was introduced into the furnace through the tube, F, Fig. I , the capillary, E, having been removed. By removing the graduated cylinder, I , the hydrogen was forced out of the vertical glass tube a t the bottom of the trap, Z. The end of this tube was immersed in water which partly filled an Erlenmeyer flask and through which the gas bubbled. When the temperature a t which the experiment was to be carried out had been reached, the flow of hydrogen through the apparatus was stopped and the capillary tube, E, replaced into the tube, F. The graduated cylinder, I , was also replaced. Ten cubic centimeters of the kerosene fraction were placed in the glass tube, D, and the rubber hose, B, placed on top. The mercury tube was then raised to generate a slight pressure on the liquid in D and the screw clamps, 2 , were opened to allow the gaseous products to pass into the gas collecting bottle. The bottle into which the gas passed and the glass tubing connecting it with the U tube, 3, was previously filled with water. The leveling bottle of the gas-collecting apparatus was so adjusted that the level of the water in it was slightly below that of the water in the bottle into which the gas was passing, thus assuring an unhindered flow of gas into the bottle A constant rate of flow of the kerosene into the reaction chamber was maintained throughout the experiment by means of the mercury leveling tubes, A. After a few cubic centimeters of liquid had been passed over the catalyst, the hydrogen which was contained in the furnace had been replaced by the products of the catalytic decomposition. The U tube, 3 , was then disconnected from the gas collecting bottle and connected to a gas burette for the purpose of obtaining a sample of the gaseous product for analysis. The sample having been taken, the C tube was again connected as before and the experiment completed. When all of the liquid had passed into the furnace. the screw clamps, 2 , were closed and the graduated cylinder, I , loosened frorr the rubber stopper. The capillary tube, E, was then removed from the feed tube, F, and hydrogen passed through the furnace at the rate of 14 liters per hour to wash out all of the liquid products of the reaction. This liquid product was collected and measured in the graduated cylinder. Estimation of the Products The gaseous products obtained from the experiments were analyzed by means of absorption 2nd combustion with the use of Hempel gas apparatus. S o attempt was made t o determine any single hydrocarbon other than methane in the gaseous mixture obtained from the decomposition. The gaseous hydrocarbons higher than methane in the paraffin series were determined by absorption in absolute alcohol. The gas was then passed into an absorption pipette containing a 3 0 7 0 solution of potassium hydroxide to remove any
CATALYTIC DECOMPOSITION OF KEROSENE
2695
traces of carbon dioxide which it might contain. The unsaturated hydrocarbon gases were determined by passing the gas into a pipette containing saturated bromine water, the bromine fumes being removed by means of the potassium hydroxide pipette. The gas was then passed into a pipette containing a solution of pyrogallic acid in strong potassium hydroxide to determine and remove traces of oxygen. Finally it was passed into a pipette containing ammoniacal cuprous chloride solution to determine carbon monoxide if present. About twenty cubic centimeters of the remaining gas were placed into a Hempel explosion pipette over mercury in order to determine the per cent of hydrogen and methane by the Hempel method. This method affords a relatively accurate determination of these two gases by a single combustion with oxygen. The accuracy of the determination of the constituents of the gaseous mixtures is within 0.1to 0.3% for the absorptions, 1% for methaneand I to370 for hydrogen. The total quantity of the gas obtained as a product from the experiments was measured by means of calibrations on the side of the gas-collecting bottle. The hydrogen remaining in the reaction tube and adsorbed on the catalyst before kerosene was passed over the catalyst was found by experiment to be negligible in regard to the accuracy of the measurement of the total volume of the gas collected. I n the experiments where liquid was obtained as a product, the volume of the liquid was measured in the graduated cylinder, I , Fig. I . The density of the liquid product was accurately determined by means of a pycnometer. The iodine number of the liquid product and of the kerosene fraction passed over the catalyst was determined in the manner described by Kamm.’ The carbon which was deposited on the catalyst was determined by burning with oxygen and absorbing the carbon dioxidein two Geissler potash bulbs connected in series. The oxygen purified from COZ and water vapor was passed over the catalyst in the reaction tube at 300’ C. The resulting gas containing COP and an excess of oxygen was passed, first through a U tube containing calcium chloride, then through two weighed potash bulbs and finally through a weighed V tube containing calcium chloride. The weight of carbon was calculated from the increase in weight of the two potash bulbs and the last calcium chloride tube. This absorption train was connected to the liquitl trap, Z, Fig. I . After the determination of carbon, it was necessary to reduce the catalyst with hydrogen before the next experiment was carried out.
Materials used The kerosene fraction used in all the experiments was obtained from commercial kerosene. The kerosene was shaken with concentrated sulphuric acid three times, separated from the acid by means of a separatory funnel and then fractionally distilled. The fraction used was that which boiled between zoo Oliver Kamm: “Qualitative Organic Analysis,” page I i o .
2696
E. W. KANNING AND 0. W. B R O W
C. This liquid was a clear, colorless material having a density of and an iodine number of z;.6. The hydrogen used in the reduction of the catalysts was commercial electrolytic hydrogen. Before passing into the furnace, th8 hydrogen was purified by passing over hot copper, through concentrated sulphuric acid, glass wool and then through a caustic soda tower. This purification removed all traces of oxygen and water vapor. The oxygen used in the determination of the carbon deposited on the catalyst' was commercial electrolytic oxygen. It was purified by passing through concentrated sulphuric acid and over soda lime and calcium chloride. This treatment removed traces of water vapor and carbon dioxide. The cobalt nitrate from which the cobalt catalyst was prepared was Mallinckrodt's C.P. Quality Co(N03)2. 6H20, containing 0.307~ alkali salts, o.o1y0 chlorine, , 0 0 2 7copper, ~ 0.000% iron, o.oz% lead, 0.60% nickel, 0.017~ sulphate and 0 . 0 8 7 ~zinc. The ferric nitrate from which the iron catalyst was prepared was Baker's Analyzed Fe(N03)3,9H20 and contained no copper or zinc, .OOI% chlorine and . O O I % SOa. The manganese sulphate from which the manganese catalyst, was prepared was Coleman and Bell's hInSOa.4H20, containing 0 . 0 2 % calcium, 0.005% chlorine, 0.00370 iron, 0 . ~ 0 0 %magnesium and alkalies, a trace of reducing matter, and 0.0 ;yo zinc. The nickel nitrate used in the preparation of the nickel catalyst was Baker's Analyzed S i ( N 0 3 ) ~ . 6 H and ~ 0 contained . O O I % cobalt, no copper, .OOI% iron, ,0017~ chlorine and . O O I ~SOs. ~ The pumice stone used as catslyst support, was treated in the following manner. Lump pumice stone was crushed in a Blake crusher and sizes ranging from 3/16 to I / Z inch were used for treatment. The crushed material was boiled in I : 5 nitric acid for four hours. I t was then washed free of acid on a Buchner funnel with distilled water and dried in an oven at 10 j' C. for eight hours. The resulting material was used as the support for all the catalysts in this investigation. and
230'
.;8;9
Preparation of the Catalysts The cobalt catalyst used in this investigation was prepared in the following manner: 2 4 7 g. of cobalt nitrate were dissolved in a small amount of vater. To this solution, 2 5 g. of pumice stone were added and the mixture boiled for ten to fifteen minutes to saturate the pumice stone with the solution. Cobalt hydroxide was precipitated with a slight excess of a I 5% solution of sodium hydroxide. The precipitate was washed free of alkali on a Biichner funnel with distilled water and dried at 10j"C. in an oven for eight hours. The material was reduced in the furnace at 400' C. for two hours in a stream of hydrogen flowing at the rate of 1.1liters per hour. The resulting cobalt nietal 'catalyst supported on 2 5 g. of pumice stone weighed 50 grams. The iron catalyst was prepared as follows: 361.7 g. of ferric nitrate were dissolved in a small amount of water and boiled for ten to fifteen minutes with
CATALYTIC DECOMPOSITION OF KEROSENE
2697
2 5 g. of the pumice stone. Ferric hydroxide was precipitated with an excess of a I : I solution of ammonium hydroxide. The resulting precipitate was washed free of ammonium hydroxide on a Buchner funnel and dried a t 105' C. for eight hours. The dried material was reduced for two hours a t 415' C. in a stream of hydrogen of 14 liters per hour. The catalyst material consisted of 50 g. of metallic iron supported on 25 g. of pumice stone. The manganese catalyst was prepared as follows: 202.9 g. of manganese sulphate were dissolved in as little hot water as possible. To this solution, 25 g. of pumice stone were added and the mixture boiled for ten to fifteen minutes. Manganese hydroxide was precipitated by the addition of a slight excess of I : I ammonium solution. The precipitate was washed free of ammonium hydroxide and also sulphates on a Buchner funnel and dried for two hours in an oven at 105' C. The dried material was placed in the furnace and reduced for two hours at 43 joC. in a stream of hydrogen of 14 liters per hour. The resulting catalyst material consisted of j o g. of manganese metal supported on 25 g. of pumice stone. I n the preparation of the nickel catalyst, 247.7 g. of nickelous nitrate were dissolved in a small amount of hot water. To this solution 2 5 g. of pumice stone were added and the mixture boiled for ten to fifteen minutes to impregnate the pumice with the nickel nitrate solution. Xckel hydroxide was precipitated by the addition of a slight excess of a I 5% solution of sodium hydroxide. The precipitate was washed free of alkali on a Buchner funnel and dried for eight hours at 105' C. The dried material was reduced a t 350' C. for two hours in a stream of hydrogen of 14 liters per hour. The catalyst material consisted of j o grams of metallic nickel supported on 25 grams of pumice stone.
Cobalt Catalyst
A number of experiments were carried out with a cobalt catalyst prepared in the manner previously described, in order to determine the effect of temperature on the catalytic decomposition of 'the kerosene fraction. Other experiments were made for the purpose of determining the effect of the rate of flow of the liquid passed over the catalyst. I n the experiments carried out at various temperatures, the quantity and rate of flow of the liquid passed into the reaction chamber were kept constant, ten cubic centimeters being passed in sixty minutes. In determining the effect of the rate of flow of the liquid, the temperature and quantity ( I O cc.) of the liquid were kept constant. In the experiments in which the temperature was the variable factor the following determinations were made and recorded : the total volume of gas obtained as product from the ten cubic centimeters of kerosene passed over the catalyst, the volume of liquid product, the per cent of hydrogen and methane in the gaseous product, the per cent of gaseous paraffin hydrocarbons above methane in the series, per cent of gaseous hydrocarbons of the unsaturated series, the grams of carbon deposited by the decomposition and the iodine numbers and densities of the liquid products in those experiments where liquid was obtained.
2698
E. W. KANNING AND 0. W. BROWN
Table I shows the effect of temperature on the volume and composition of the gaseous product obtained with the cobalt catalyst.
TABLE I Volume of Kerosene Fraction passed: I O cc. Rate of Flow of Kerosene Fraction: I O cc. per hour. Catalyst: j o g. of cobalt on 2 j g. of pumice. Volume of gas obtained in cc.
Per cent hydrogen in gas
Per cent methane in gas
495
49.70
498
50.70
663 1980 4800
56. I O 61.50
37.50 32.40 29.20
9715 9842 9990
I0040
65.40 68.76 68.85 69.81 69.80
Per cent gaseous paraffins above methane in gas
Per cent gaseous unsaturated hvdrocarbons in gas
10.80
0.00
9.40
0.00
8.30 6.40
0.00
25.60
5.40
0.20
24.47
2.20
0.30
24.47 24.26
3.20
0.40
3 ' I4 3.22
0.62
26.40
24.00
0.00
0.50
It is most apparent from Table I, that, as the temperature is increased, the volume of gas obtained from I O cubic centimeters of the kerosene fraction increases greatly. At 550' C. over 1,000volumes of gas are obtained from one volume of liquid. The following curves, Fig. 2 , show the temperature plotted as abscissa and per cent as ordinates. Curve I represents the per cent of hydrogen in the gaseous product obtained at various temperatures and Curve 2 the per cent of methane. From Curve I , Fig. 2 , it is seen that the per cent of hydrogen in the gaseous product increases with the temperature at which the experiment is carried out. When 525' C. is reached the production of hydrogen seems to have reached a maximum since a t j j o o C. there is no further increase. From Curve 2 , Fig. 2 , it is seen that the per cent of methane in the gas decreases as the temperature is increased. The per cent of methane approaches a minimum at 5 2 j' C. since the curve nearly straightens out horizontally at that point. Therefore, a t 5 2 5 ' C. cobalt attains an activity greater than that at any lower temperature studied and there is no marked increase in activity at 550' C. over that obtained a t 525' C. The per cent of paraffin hydrocarbons which are gaseous at ordinary temperature and higher than methane in the series, and all gaseous hydrocarbons which can be absorbed by absolute alcohol, decreased with an increase in temperature up to 5 2 5 ' C., as is seen in Table I. X o unsaturated hydrocarbons were found in the gas until 450' C. was reached. At no time was the amount of unsaturated gaseous hydrocarbons sufficiently great to warrant
CATALYTIC DECOMPOSITION OF KEROSENE
2699
further investigation. The excess of hydrogen present a t all times seems to have hydrogenated to a great extent any unsaturated gases which might have been formed. From 290 t o 450' C. inclusive, Table 11, it is noted that liquid was obtained as a product when ten cubic centimeters of the kerosene had been passed over the catalyst. No liquid was obtained, however, a t 500' C. When-
50-'
s u
40
s 0
DEG. t€N7: FIG.2
ever liquid did not appear after ten cubic centimeters of the kerosene had been passed into the furnace, an experiment was performed to determine the volume of kerosene which could be passed over the catalyst before a liquid product appeared. At 500' C. it was not until 3 2 . j cubic centimeters of kerosene had been passed before a liquid appeared as product. At 510, 5 2 5 and 550' C. one hundred ten cubic centimeters of kerosene were passed continuously & the rate of I O cc. per hour without the appearance of a liquid product, but 97,950 cc., 99,800 cc. and 103,joo cc. gas respectively were obtained, or, for
E. W. KANNING AXD 0 TV. BROWN
2700
every I O cc. of kerosene passed, 8,904, 9,072 and 9,309 cubic centimeters respectively of gas were obtained. These figures agree well with those shown in Table I In each case when I I O cc. of kerosene had been passed, the catalyst appeared to be still as active as at first but the accumulation of carbon within the catalyst tube mechanically stuffed the tube making it difficult to force more kerosene over the catalyst At temperatures lower than j o o " C. it seemed that the deposition of carbon blanketed the catalyst thereby rendering it less active. A greater quantity of carbon was deposited a t temperatures above 500' C , but, as the nature of the carbon deposited at these temperatures was probably less amorphous its blanketing action a a s much less pronounced. Gault and his co-workers also found that the catalyst was poisoned more readily at the lower temperatures.
TABLE I1 Volume of Kerosene passed: I O cc. Rate of Flow of Kerobene: I O cc per hour. Catalyst: 50 g of cobalt on 2 5 g of pumice. Temp "C
Grams carbon
c c of liquid product
290
0
'479
9 2
305 35 0
0 I240
400 450
0
9 2 9 0 7 0
0
500
3 0692
550
3.2480
__
7736 8554
Densit? of liquid product 0 7740 o 7760 0 i751
Iodine numher of liquid product
28 o 29 3 32 I
0 0
o 7815 0 7847 0 7849*
0.0
--
_-
4 5
35 1 42 I"
*These values were obtained from a liquid product which was produced a t jOO'C. after 3 2 . j cc. of the kerosene had been passed over the catalyst. The fist I O cc. did not yield a liquid product.
Table I1 shows the effect of temperature on the volumes, densities and the iodine numbers of the liquid products obtained. The table also gives the grams of carbon deposited in the catalyst tube by the decomposition of I O cc. of the kerosene fraction. From Table 11, it can be seen that the volume of the liquid product decreases as the temperature is increased. This shows an increase in the activity of the cobalt catalyst on the decomposition of the kerosene fraction as the temperature is raised. At 500' C., all of the ten cubic centimeters were converted into a gaseous product as no liquid product was obtained. The iodine numbers of the liquid products increased which shows that as the temperature was increased, the liquid product became more unsaturated. It is noticed in Table I1 that with cobalt as a catalyst the iodine numbers of the liquid products obtained were always higher than that of the kerosene originally passed into the furnace. This indicates that d t h cobalt as a catalyst there
CATALYTIC DECOMPOSITION OF KEROSENE
2701
was always a tendency for the liquid to become dehydrogenated rather than hydrogenated, even though there was an excess of hydrogen present at all times. The iodine numbers of the liquid products obtained at the various temperatures are plotted as ordinates and the temperatures as abscissa. The resulting curve for cobalt is Curve I , Fig. j, where it is plotted along with similar curves for the other catalysts studied in this investigation. The densities of the liquid produced can be seen to increase slightly as the temperature at which the reaction is carried out increases. This is probably due to the formation of hydrocarbons of higher carbon content. The carbon deposited in the catalyst tube from the decomposition is proportional to the quantity of liquid decomposed by the catalyst. Thus it can be seen that the grams of carbon increase with an increase of temperature and also increase with an increase of gas formed.
TABLE I11 Temperature: 500' C. Quantity of Kerosene passed: I O cc. Catalyst: 50 g. of cobalt on 2 j g. of pumice. Time required t o pass I O cc. of kerosene in minutes
45 30 20
Yolume pf gas in cc. 9,ijO
9,550 6,500
Volume of !iquid in cc.
Per cent hydrogen in gas
Per cent methane in gas
none none 3.5
67.2 68.1 67 .'I
25.3
2.4
26.0
2.8 3.0
2j.z
Per cent higher hydrocarbons in gas
In order to determine the effect of the rate at which the kerosene was pas?ed over the catalyst, a series of experiments were carried out at 500' C. using a new cobalt catalyst, prepared in the same manner as before. Ten cubic centimeters of the kerosene fraction were passed over the catalyst in each experiment at a definite rate. Table I11 shows the effect of the rate of flow on the volume of the gaseous products, the volume of the liquid products and the per cent of hydrogen, methane and higher saturated hydrocarbons in the gas. From Table I11 it can be concluded that a rate of flow of ten cubic centimeters of the kerosene in twenty minutes was too great for the 50 grams of cobalt catalyst to convert the kerosene into all gas, since liquid product appeared. The analysis of the gaseous products indicated practically no change in :he per cent of hydrogen, methane and gaseous paraffins above methane in the series. The volume and analysis of the gaseous products obtained from these experiments compare very closely with those of the gas obtained in the previous experiments at j o o o C., Table I. From Table 111, it is seen also that thirty minutes is as fast as ten cubic centimeters of the kerosene can be passed over 50 grams of catalyst and still give all gas as product.
Iron Catalyst -in iron catalyst was prepared from ferric nitrate in the manner previously described. Experiments were carried out with this catalyst in the same manner as with cobalt in order to determine the effect of temperature on the following
E. W. KASNING AND 0. W. BROWN
2 702
factors: volume of gaseous product, composition of gaseous product, volume of liquid product and its density and degree of unsaturation as indicated by the iodine number. Table I V shows the effect of temperature on the volume and composition of gas obtained. In all the experilnents with iron as catalyst the rate of flow of the kerosene fraction was kept constant a t I O cc. per hour.
FIG.3
TABLE 11' Quantity of Kerosene passed: I O cc. Rate of Flow of Kerosene: I O cc. per hour. Catalyst: 50 g. of iron on 2 5 g. of pumice. Volume of gas obtained in cc.
Per cent hydrogen in gas
350
none none
-
400 450
2350
Temp. "C. 300
505
555
622 4500 9500
90.5
86.9 75.9 61.6
Per cent methane
in gas
3.62 4.IO 8.50 18.20
Per cent gaseous paraffins above methane in gas
Per cent gaseous unsaturated hydrocarbons in gas
-
-
-
-
0.00
0.00
0.40 8.00 I 1 .oo
0.00 0.00 0.00
The curves, Fig. 3, show the temperature plotted as abscissa and per cent as ordinates. Curve I represents the per cent of hydrogen in the gaseous product and Curve 2 represents the per cent of methane. From Curve I , Fig. 3, it can be seen that the maximum per cent of hydrogen in the gaseous product is obtained a t 400' C. The volume of gas obtained a t this temperature, Table IV, is, however, considerably less than that obtained a t the higher tempera-
CATALYTIC DECOMPOSITION O F KEROSENE
2 703
tures. From this it is noted that the temperature which yielded the highest per cent of hydrogen in the gaseous product did not yield the greatest volume of gas. Curve 2 , Fig. 3, shows that the per cent of methane in the gaseous product increases with the temperature. It is also noted here that a t 550' C., 18.2y0 methane was obtained while only 59.6% hydrogen was obtained, or, in other words, of all the temperatures used, 550' C. gave the highest yield of methane and the lowest yield of hydrogen, which is quite different from the results obtained with cobalt as catalyst. The per cent, of paraffin hydrocarbons other than methane which are gases a t ordinary temperatures, increased with an increase in temperature as shown in Table IV. There were no unsaturated compounds present in the gaseous product with iron as the catalyst. TABLE
v
Quantity of Kerosene passed: I O cc. Rate of Flow of Kerosene: I O cc. per hour. Catalyst: 50 g. of iron on 2 5 g. of pumice. Temp. "C.
Grams of carbon deposited
300 350
0,0000
400
0.136; 0.2923 0.5193
450
505 555
0.0000
--
cc. of
liquid product
9.2 9.0 8.8
Density of liquid product
0.766; 0 .;;oq
Iodine number of liquid product
22.3 26.0 32.8
7.0
0 .j 6 i 8 0,7645
40.9
6.0
0 .j 6 2 8
52.2
0.0
--
-
Table V shows the effect of temperature on the volume of liquid produced, the density and iodine number of the liquid, and, also, the grams of carbon produced by the decomposition. From Table V, it is noticed that as the temperature was increased, the grams of carbon deposited also increased and that the volume of liquid product decreased. The densities of the liquid products did not vary to a great extent as the temperat'ure was raised, but the iodine numbers increased to a marked degree. This shows an increase in unsaturation as the temperature rose. Curve i, Fig. 5 , shows this variation in the iodine number as the temperature of the reaction was varied. The maximum unsaturation was obtained a t j j joC. The values for the iodine numbers of the liquid produced a t 300 and 350' C. were lower than that of the kerosene passed into the furnace, which was 2 7 . 6 . This shows that a t the lower temperatures a slight hydrogenation of the kerosene took place. Except for this very slight hydrogenation of the liquid, there was very little action on the kerosene a t 300 or 350' C., since no gaseous product was obtained in either case. At 5 5 joC. 80 cubic centimeters of the kerosene were passed over the iron catalyst at the rate of I O cc. per hour without the appearance of a liquid
E. W. KASNISG AND 0. W. BROWN
2704
product. At various intervals during the introduction of the kerosene into the furnace, samples of the gaseous product mere collected and analyzed. It, was found that the analyses of these samples checked very closely with each other, showing that the gas remained of the same composition throughout the experiment. I t was apparent that the kerosene could not be passed over the catalyst faster than 10 cc. per hour, without the formation of a liquidproduct. The total volume of the gas obtained from the 80 cc. of kerosene was 78,100 cc. which is 9 r 7 8 7 . 5 cc. per I O cc. of kerosene. This latter value agrees very well with the volume of the gas obtained a t the same temperature as shown in Table IT. Manganese Catalyst Experiments with manganese as catalyst, prepared as previously described, were carried out' in order to determine the effect of temperature on the various factors which were studied in the case of cobalt and iron. Table TI shows the effect of temperature on the gaseous product resulting from the decomposition of the kerosene fraction over the manganese catalyst.
TABLE VI Quantity of Kerosene passed: I O cc. Itate of Flow of the Kerosene: I O cc. per hour. Catalyst: 50 g. of manganese on 2 5 g. of pumice. Temp. "C.
300
370
Volume of ~ Y S obtained in cc.
Per cent hydrogen in gas
none none
__
__
76.0 68.8 1j.6
400
515
500
1550
5 50
2130
-
Per rent methane in gas
Per c r n t Per rent gaseous gaseuus paraffins unsaturated above CHI hydrocarbons in gas In gas
-
-
6.6
8.0
0.0
8.I
19.2
0.0
22.9
54.8
0.0
__
S o gas was obtained as product with manganese as catalyst at 300 or c'. Gas appeared as a product at 400' C. and increased in volume as the temperature was raised, as shown in Table VI. It is noted also that manganese did not yield large volumes of gas as did cobalt and iron over the same temperature range. From Table V I is can be seen that with manganese as catalyst the per cent of hydrogen in the gaseous product decreased as the temperature of the reaction was increased. The hydrogen content of the gas is seen to have dropped as low as 15.6 per cent. As the temperature was increased, the per cent of methane in the gaseous product' increased and reached a maximum of 2 2 . 9 at 550' C. At 550' C. the per cent of gaseous paraffin hydrocarbons above methane in the series was j3.8 which indicates that manganese has the specific activity of producing this stage of decomposition at this temperature. It is seen also from Table TI that no unsaturated gaseous hydrocarbons were obtained, as was also the case when iron was used as catalyst. 370'
CATALYTIC DECOMPOSITION OF KEROSENE
2705
Table VI1 shows the effect of the temperature variation on the liquid product obtained and also the grams of carbon deposited.
TABLE VI1 Quantity of Kerosene passed: I O cc. Rate of Flow of Kerosene: I O cc. per hour. Catalyst: jo g. of manganese on 2 5 g. of pumice. Temp. "C.
Grams carbon deposited
c c . of liquid product
Density of liquid product
300 370
none none
9.7 9.5
0.7770 0.7764
400
0.1862 0.3412 0.3874
9.2
0.7780
8.5 5.5
0.7834 0.7987
500
550
Iodine number of liquid product
26.53 27.16 28.99 48.I O 73.02
From Table VII, it, can be seen that the activity of the manganese catalyst increases with the temperature, as shown by the diminishing volume of liquid obtained as product and the increasing amount, of carbon deposited. The iodine numbers of the liquid products, indicating the degree of unsaturation, became larger as the temperature was increased. The density of the liquid rises slightly with the temperature but not to any marked degree. The iodine numbers are plotted as ordinates and the temperature as abscissa, Curve 3, Fig. 5 .
Nickel Catalyst The effect of temperature on the various factors encountered in the decomposition of the kerosene fraction was also studied using nickel as the catalyst, which was prepared as has been previously described. Table VI11 shows the effect of temperature on the volume and composition of the gaseous product obtained with nickel. TABLE VI11 Quantity of Kerosene passed: I O cc. Rate of Flow of Kerosene: I O cc. per hour. Catalyst: j o g. of nickel on 2 5 g. of pumice. Volume of gas obtained in cc.
Per cent hydrogen in gas
Per cent methane in gas
Per cent gaseous paraffins above CHa in gas
310 390 450
none
-
-
-
I452 I 780
46.4 57.0
36.40 26.20
1.1
8.0 6.8
500
2000
5.5
3250
Ij.80 9.04
12.0
550
59.2 38.1
44.7
1.3
Temp. "C.
0.0
Per cent gaseous unsaturated hydrocarbons in gas
2706
E. W. KANNING AND 0.W. BROWN
Curve I , Fig. 4,shows the effect of temperature on the per cent of hydrogen in the gaseous product obtained from the decomposition of the kerosene fraction over nickel catalyst. The curve shows a maximum production of hydrogen a t 500' C. Higher or lower than 500' C. the per cent of hydrogen in the gas decreases quite rapidly. Curve 2 , Fig. 4, shows the effect of temperature on the per cent of methane in the gaseous product. The methane content seemed to steadily decrease with a rise in temperature, the minimum per cent of methane being obtained at 550' C. and the maximum a t 390' C.
FIG 4
From Table VIII, it can be seen that, with nickel as catalyst, the per cent of hydrocarbon gases of the paraffin series which are above methane increased as the temperature was raised. h decided increase was found from 500 to 550' C., the per cent of these gases being 12.0 and 3 q . j respectively. Unlike any of the other catalysts, nickel causes an appreciable production of unsaturated gaseous hydrocarbons as is seen in the table. The per cent of these unsaturates decreases with an increase in temperature, from 8.0% a t 390' C. to 1.3% at j joo C. At 3 10' C. no gaseous product was obtained, but the volume of gas steadily increased as the temperature was raised to reach a maximum of 3 , 2 j o cubic centimeters at 550' C. from ten cubic centimeters of kerosene. It is noted that the volume of gas obtained with nickel at 5 joo C. is considerably less than that obtained with cobalt and iron but not less than that obtained with manganese. Table IX shows the effect of temperature on the volume, density and iodine number of the liquid products and also the grams of carbon deposited from the experiments with nickel as catalyst.
CATALYTIC DECOMPOSITION O F KEROSENE
2707
TABLE IX Quantity of Kerosene passed: I O cc. Rate of Flow of Kerosene: I O cc. per hour. Catalyst: 50 g. of nickel on 2 j g. of pumice. Temp. "C.
Grams of carbon deposited
c c . of liquid product
3'0 390 450
none
10.0
0.087j
8.8 8.5 7.5 3.5
500
550
0.2764 0.5787 0.1630
Density of liquid product
0.7882 0.7689 0.7742 0.7703 0.8063
Iodine number of liquid product 27. IO
28.02
36.40 j o . 76 70.99
FIQ.5
From Table IX, it is evident that the grams of carbon deposited increased with the temperature until 550' C. was reached. The amount of carbon deposited a t 550' C. was less than that deposited a t 50o'C. probably because a greater per cent of gaseous hydrocarbons was found in the former case. The extent of the decomposition was greater a t joo' C. because, in the latter case, nearly half of the volume of the gas produced was composed of hydrocarbons of the paraffin series above methane, Table VIII. The volume of the liquid products decreased as the temperature was raised and as a greater volume of gas was produced. The iodine numbers of the liquid products increased with the temperature, which shows a higher degree of unsaturation of the liquid products at the higher temperatures. At 310' C. there was apparently no decomposition over the nickel catalyst since the volume, density and iodine number of the liquid product were the same as those of the liquid passed into the furnace. Curve 4, Fig. j, represent the iodine numbers plotted as ordinates and the temperature plotted as abscissa.
2708 \
E. W. KANNING AND 0 . TV. BROWN
Comparison of the Catalysts In comparing the activity at the various temperatures of the four catalysts, cobalt, iron, manganeses and nickel, for the decomposition of the fraction of kerosene boiling between zoo and 230' C., the following factors are noted: the volume of gaseous product obtained from ten cubic centimeters of the kerosene, the per cent hydrogen, methane, saturated gaseous hydrocarbons above methane in the paraffin series and unsaturated hydrocarbons in the gaseous product, the volume of liquid product obtained from I O cc. of the kerosene, and, the density and degree of unsaturation of the liquid product as shown by the iodine number. The cobalt catalyst appeared to be the most active of those studied. Cobalt was the only catalyst of those studied found to convert I O cc. of the kerosene to gas in less time than one hour over j o g. of catalyst without the formation of a liquid product. The volume of gas obtained with all four catalysts from I O cc. of kerosene increased with an increase in temperature. The maximum volume of gas obtained with each catalyst was at 5 j o " C., the highest temperature used. With cobalt, the per cent hydrogen in the gaseous product increased as the temperature was raised, while with iron and manganese the per cent of hydrogen steadily decreased with a rise in temperature. When nickel was used as catalyst, the per cent of hydrogen in the gaseous product of the reaction reached a maximum at 500' C. These facts illustrate the specific action of the catalysts and no set rule can be formulated to explain these differences in activity. The highest per cent of hydrogen in the gaseous product was obtained with iron as catalyst a t 400' C. This value was 9 0 . 5 7 ~as~seen in Table IT. However, the quantity of liquid decomposed under these conditions was low compared with that obtained at the same temperature with cobalt. The per cent hydrogen in the gaseous mixture obtained over cobalt at 400' C. was 61.5. Manganese and nickel are less active a t this temperature and are inferior t o cobalt and iron for the production of gas. At higher temperatures, all of the catalysts gave more gaseous product from the ten cubic centimeters of the kerosene passed. However, with an increase in temperature the per cent of hydrogen in the gas decreased when iron and manganese were used as catalysts. When nickel was used, the maximum yield of hydrogen in the gas was reached a t joo' C. The yield dropped to 38.1% a t j50' C. The most suitable catalyst for the production of the gaseous product seems to be cobalt, since the maximum volume of gas was obtained from ten cubic centimeters of kerosene and contained a per cent of hydrogen of 69.8. Iron was found to be second to cobalt for gas production and nickel and manganese, third and fourth, respectively. With cobalt and nickel, the per cent of methane in the gaseous product decreased as the temperature was raised, while with iron and manganese this factor increased with the temperature. The maximum per cent of methane,
CATALYTIC DECOMPOSITION OF KEROSENE
2709
46.4, was obtained with nickel a t 390' C., while the highest per cent obtained with cobalt was 37.5 at 290' C. With cobalt and nickel as catalysts the production of methane was greater than with iron or manganese. I n Tables VI and VIII, it is seen that the per cent of saturated hydrocarbon gases above methane was 54.8 and 44.7 over manganese and nickel, respectively. This fact is peculiar to these two catalysts only. In neither the case of cobalt nor iron was there so great a per cent' of these hydrocarbon gases obtained. Sickel, unlike any of the other catalysts studied, caused appreciable amounts of unsaturated hydrocarbon gases to be produced, the gas mixture containing 8.0% a t 390' C. Cobalt was the only other catalyst giving these unsaturates in the gas produced. The gas obtained a t j j o " C. contained 0.62%. With all four catalysts, the volume of liquid products decreased with an increase in temperature. This is the result of a more complete decomposition with rise in temperature. S o liquid was obtained above joo' C. with cobalt or at j jj" C. with iron, while with manganese and nickel, liquid products were obtained at all the temperatures studied. If t'he manganese or nickel were used at higher temperature, it would be expected that the products u-ould be all gaseous. The iodine numbers of the liquids obtained increased with the temperature in all cases where liquid products were obtained. This agrees with similar work by Gault and his co-workers. The highest degree of unsaturation of any liquid produced was obtained a t 5jo' C. with manganese as catalyst. Its iodine number was 73.02. The highest iodine number obtained with nickel as catalyst was 70.99 a t j 50' C. Fig. j shows the iodine numbers plotted as ordinates and the temperature as abscissa for each of the four catalysts. The carbon deposited by the decomposition of the kerosene which passed over the catalyst was proportional to the temperature employed, the higher the temperature the more carbon deposited. I t mas found that in all experiments the carbon deposited at low temperature rendered the catalyst inactive, while that formed at a more elevated temperature had little or no effect on the activity. This is cspeciaily brought out in the experiments on cobalt. d s is noted in Table 11, above j o o o C. the activity of the catalyst was in no way impaired by the deposition of large quantities of carbon. Further investigation concerning the catalytic decomposition of hydrocarbons is now being conducted by the writers. In the continuation of this work, other Catalysts are being used and the decomposition of hydrocarbon fractions boiling higher and lower than the kerosene used in this investigation is being studied. Experiments to study the decomposition of commercial gas oil over a cobalt catalyst at j o o " C. have been conducted. Gas oil which has a boiling range higher than that of kerosene, when passed over a cobalt catalyst at the rate of I O cc. per hour, decomposed into a gaseous and liquid product. The volume of gas obtained from I O cc. of the oil at joo' C. was 6 , 2 j o cc. The volume of liquid product was 2.j cc. The composition of the gaseous product was: 45.2% hydrogen, 32.8% methane and 17.0a/o higher paraffin hydrocarbons.
2710
E. W. KANNING AND 0.W. BROWN
This indicates that under the conditions used, gas oil does not decompose as completely as kerosene. It is believed, however, that a slower rate of flow of the oil or a second pass over the catalyst would cause a more complete decomposition. Conclusion I. With all four catalysts it was found that an increase in temperature yielded an increase in the quantity of kerosene decomposed which results in an increased volume of gaseous product, a decreased volume of liquid product and an increased deposition of carbon. 2. In the experiments where liquid products were formed, the iodine number increased with the temperature. 3 . Carbon deposited a t the lower temperatures rendered the catalyst less active, while that deposited a t the higher temperatures had little or no effect. 4. Cobalt was shown to be the best catalyst of the four studied for the production of the greatest volume of gas in the shortest time. One gram of cobalt catalyst at 550' C. will convert 0.33 g. of kerosene to 6.3 cc. of gas in one minute. 5 . I t was found that a continuous conversion of kerosene can be affected over a cobalt catalyst at 500' C. which is 50' C. lower than with iron. 6. As the temperature was increased it was noticed that in the case of cobalt as catalyst, the per cent of hydrogen in the gaseous product increased while the per cent of methane decreased. With manganese and iron as catalysts the per cent of hydrogen decreased while the per cent of methane increased. I n the case of nickel the per cent of hydrogen reached a maximum and the per cent of methane decreased as the temperature was raised. 7 . Of the four catalysts studied, only nickel gave unsaturated hydrocarbons in the gaseous product to any appreciable extent. Cobalt, however, gave traces. 8. Kickel and manganese at 550' C. favored the production of large quantities of paraffin hydrocarbon gases above methane. 9. Each of the four catalysts exhibited specific catalytic properties with regard to the nature of the products. IO. The four catalysts might be arranged in the following order in regard t o their ability to decompose the kerosene fraction boiling from zooo to 230' C . . cobalt, iron, nickel and manganese. The gas having the highest per cent of hydrogen, 90. j, was obtained I I. over iron at 400' C. 12. The gas having the highest per cent of methane, 36.4, was obtained over nickel at 390' C. Laboratory of Physzcal Chenzzslry,
Indiana Cnaverszty, Bloomzngton.
