INDUSTRIAL AND ENGINEERING CHEMISTRY
September, 1941
LIFE OF CATALYST. To determine whether the vanadium pentoxide catalyst had declined in activity during use, a final run was made duplicating one which had been made shortly after the catalyst had been prepared. During the interval between these two runs, a total of 632 grams of hydrocarbon had been oxidized by a catalyst containing 2.3 grams of vanadium pentoxide The active material, therefore, had converted 275 times its weight of hydrocarbon. The following data compare these two runs and indicate that the activity of the catalyst had remained practically constant during this period: R u n No. 14
71
Mole Ratio, On/Hydrocarbon
S ace Vegoity,
27.8 28.1
4020 3924
L./Hr
Contact Time, See. 0.20 0.20
T:T.,
464 464
Yield,
%
20.3
20
Literature Cited (1) Aschan, O., “Naphtenverbindungen, Terpene und Campherarten”, Berlin, Walter de Gruyter and Co., 1929. ( 2 ) Clark, C. K., and Hawkins, J. E., IND.ENQ.CHEM., 33, 1174 ( 1941). (3) Cook, A. H., J . Chem. S o c , 1938,1761-80.
1181
(4) Dupont, G., and Crouzet. J., Bull. inst. p i n , 101-8 (1929). (5) Dupont, G., and Zacharawicz, W., Bull. SOC. chim., [5] 2, 533-9 (1935). (6) Egloff, Gustav, “Reactions of Pure Hydrocarbons”, New York, Reinhold Pub. Corp., 1937. (7) Groggins, P. H., “Unit Processes in Organic Synthesis”, 2nd ed., New York, McGraw-Hill Book Co., 1938. (8) Kolthoff, I. N., and Furman, N. H., “Volumetric Analysis”, Vol. 2 New York, John Wiley & Sons, 1929. (9) Korotkov, K., Lesokim. Prom., 4,No. 11, 6-8 (1935). (10) Lange, N. A., Handbook of Chemistry, Sandusky, Ohio, Handbook Publishers Ino., 1934. (11) Marek, L. F., and Hahn, D. -4., “Catalytic Oxidation of Organic Compounds in the Vapor Phase”, A. C. S . Monograph 61, New York, Chemical Catalog Co., 1932. (12) Milas, N. A., and Walsh, W. L., J . Am. Chem. SOC.,57, 1389-93 (1935). (13) Schrauth, W. (to Deutsche Hydrierwerke Aktiengesellschaft), U. S . Patent 2,030,802 (Feb. 11, 1936). (14) Simonsen, J. L., “Terpenes”, Cambridge University Press, 1932. (15) Suzuki, Koji, BuEl. Inst. Phy8.-Chem. Research (Tokyo), 14, 17991 (1935); 15, 70-1 (1936). (16) Wallach, O., “Terpene und Campher”, 2nd ed., Leipzig, T’eit and Go., 1914. ABBTRACTED from a thesis submitted t o t h e Graduate Council of the University of Florida by C . K. Clark in partial fulfillment of the requirements for the degree of doctor of philosophy, August, 1940.
Theoretical Calculations for Explosives Temperatures, Gaseous Products, and Effects of Changes in Carbonaceous Material F. W. BROWN Central Experiment Station, U. S. Bureau of Mines, Pittsburgh, Penna.
A
STUDY of the mechanism of firedamp ignition by ex-
plosives is being made by the Explosives Division of - the United States Bureau of Mines a t its testing station, Bruceton, Penna. I n connection with this study it is necessary to examine in detail some of the fundamentals of the explosion process. Theoretical calculations of certain explosive quantities, although of necessity quite crude, have been found useful by many mTorkers in the field. It is believed that many of the calculations can be improved, and that by using some of the more modern data and theories of chemical reaction and structure of matter, many of the calculations can be refined, extended, and made more useful as an aid in interpreting experimental results. The explosion temperature and pressure will be defined as the equilibrium temperature and pressure attained if an explosive were completely detonated in a perfectly insulated, rigid, closed bomb with a volume equal to that of the explosive charge. Accurate calculation of such quantities would require knowledge of the heat of formation of the original explosive, the composition, heats of formation, and specific
A convenient method of calculating approximate explosion temperatures and products of explosion for liquid and solid explosives ha6 been developed. The necessary thermodynamic data have been assembled and extended. Calculations have been made of explosion temperatures and products of explosion for several oxygen balances €or a typical high ammonium nitrate explosive and a typical 60 per cent gelatin dynamite.
heats of the explosion products, and the gas law obeyed by the gaseous products of explosion. Actually, only probable upper limits can be calculated. I n addition, it is assumed that the gaseous products obey Abel’s gas law,
P(V - Vo)
MRT
where VOis determined from the hydrodynamic theory of detonation for high explosives (2,3), and spectroscopic thermodynamic data are used. Former calculations of explosion temperature have used experimental products or products calculated from only one
I N D U S T R I A L A N D E N G J: N E E R I N G C H E M I S T R Y
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Vol. 33, No. 9
or two assumed equilibria, and have been based on older thermodynamic data. Secondary reactions are known t o occur after the explosion, and the detonator probably has an apprecia'ble effect on the composition of the experimental products. The use of the calculated products is therefore indicated, and this has the additional advantage of affording information on the course of the reaction and the effects of certain deviations from equilibrium. I n the present work eleven equilibria are assumed to operate, a i d the gaseous products are calculated by a simplified method using the ratio of carbon monoxide to carbon dioxide as a variable parameter. The thermodynamic data have been revised and extended where necessary. The explosion teniperature must be calculated by successive approximations. We first assume a temperature, and then calculate the explosion products and the difference between the heat released in the explosion and the energy content of the products. This is done for a few temperatures which bracket the correct temperature. We then interpolate t o determine the temperature at which the heat released and the energy content of the products are equal. Calculations of products of explosion, explosion temperatures, heats of reaction, explosion pressures, and specific heats have been made for a high ammonium nitrate explosive, A , and a 60 per cent gelatin dynamite, B. The oxygen balance was varied by varying the amount of wrapper. The results are shomi in Figure 1. The trends indicated in the figure would be expected from the way in which the various equilibria individually depend on pressure, temperature, and concentration. The same general trends are noticed in most combustion processes (1). For equilibrium conditions the high pressures produced in the detonation of explosives tend to produce more C and CHI and less CO, OH, NO, 0 , H, N, and 0 9 than are formed in other lower pressure combustion processes. Close examination of the curves will reveal many important trends which will not be discussed here. Cert,ain effects of deviation from equilibrium conditions have been examined. The assumption of no dissociation for the overoxidized gelatin dynamit'e results in a temperature increase from 3186" to 3265" K. If, due to incomplete decomposition, 5 per cent of the nitrogen is assumed to appear as NOz, t8hetemperat'ure is inoreased approximately 15" K. If rye assume that the carbon in the underoxidized ammonium nitrate explosive first combines with the available oxygen to give carbon dioxide, and that there is not sufficient time for carbon monoxide to be formed, the temperature is increased from 2163" to 2254" K. For explosives more deficient in oxygen, this assumption may cause an increase of several hundred degrees in the calculated temperature. If, for the same explosive, we assume that incomplete decomposition causes 5 per cent of the nitrogen to appear as NOz, the temperature is reduced approximately 175" K.; and the assumption that 5 per cent of the nitrogen goes to ammonia results in a temperature reduction of approximately the same amount. Replacing the carbonaceous material by a material richer in carbon always increases the temperature and reduces the pressure for the same oxygen balance. The pressure and temperature are increased and the total moles of products are decreased by an increase in loading density.
Literature Cited I
I
90 100 110 PERCENT OF THEORETICAL OXYGEN
I
FIGVRE1. EXPLOSION PRODUCTS, TEMPERbTURE, AND PRESSURES FOR EXPLO~IVE +4(above) AND B (bt?hU)
(I) Hottel, H. C., and Eberhard, J. E., Chem. Reo., 21,439-60 (1937). (2) Roth, J. F., 2. ges. Schiess- U. Sprengstofw., 34, 193-7 (1939). (3) Schmidt, A , , Ibid.,30, 364-9 (1935); 31,8-13, 37-42, 80-4, 11418, 149-63, 183-7, 218-22, 248-52, 284-8, 322-7 (1936). ABSTRACTED from Bureau of Mine.? Technical Paper 632 (in press): published by perm,ss on of the Director, U. S. Bureau of Mines.
