LYLE F. ALBRIGHT, STEPHEN A. LOCKE,' and DONALD R. MAC FAR LANE^ Purdue University, Lafayette, Ind. GERALD 1. GLAHNa University of Oklahoma, Norman, Okla.
Effect of Surface on
Vapor Phase Oxidation and Nitration of Propane
Nitration and oxidation reactions involving oxygen in four tubular reactors and a molten salt reactor show that reactor surface does have a definite effect on oxidation and nitration of propane
S u w A m effects are of importance for both vapor phase oxidation of propane (72, 75, 20) and nitraiion of propane (4, 9, 77). Both reactions occur by means of free radical mechanisms (7, 8, 75, 20) and surface reactions must occur either as initiating. propagating, or terminating steps. Oxidation reactions for several paraffins have a negative temperature coefficient at temperatures from about 350' to 400' C. ( 7 5 , 75). Some investigators (74) believr that surface reactions are responsible for this phenomenon, but others (20) attribute it to the concentrations and reactivities of the free radicals in the gas phase. The products obtained, however, vary with temperature. For example, propane reacts with oxygen at about 350° to 390' C. to form oxygenated products including peroxides, aldehydes, and alcohols (75, 20). I n addition, some oxides of carbon, mainly carbon monoxide, and water are formed. At higher temperatures. however, appreciable quantities of carbon dioxide, water, and olefins are produced, but smaller Present address, Commercial Solvents Gorp., Terre Haute, Ind. Present address, Argonne National Laboratory, Lemont, Ill. Present address, Phillips Petroleum Co., Bartlesville, Okla.
b
Reactor surface for the vapor phase nitration and oxidation of propane is important. Surfaces favoring nitration reactions minimize oxidation reactions and vice versa. Glass and steel reactors give much higher nitration conversions than a copper reactor. When small quantities of oxygen are added to a mixture of propane and nitric acid fed to a molten salt reactor, nitration conversions are not increased although similar experiments in tubular reactors had previously shown large increases. Oxidation runs in a molten salt reactor have demonstrated that the low-temperature partial oxidation of propane with oxygen was completely suppressed. Above 440° C. the high-temperature partial oxidation reaction began yielding carbon dioxide, water, and olefins, but no oxygenated products.
b
Initial steps in the low-temperature partial oxidation reaction occur at a suitable surface, and the molten salt did not provide such a surface. Initial steps of the vapor phase nitration reaction, however, occurred in the gas phase.
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Four types of tubular reactors were used for nitrating propane: glass, Type 304 stainless steel, carbon steel, and copper amounts of oxygenated products are obtained. Both oxidation and nitiation reactions are highly exothermic and rapid so that temperature control is often a problem. Explosions have been experienced, for example, in tubular reactors when ratios of paraffins to nitric acid of less than 2 to 1 were employed (70). N o explosions occurred, however, in a molten salt react01 at lower ratios ( 6 ) , presumably because of the excellent temperature control of the reacting gases. Because the reaction conditions for oxidation and nitration are similar, some of the factors affecting the reactions are probably identical. In this respect when small amounts of oxygen are added to mixtures of propane and nitric acid being fed to a tubular glass reactor, conversions of nitric acid to nitroparaffins were increased significantly, in some cases u p to 50 to 60% (3, 8). These improved conversions are presumably caused by higher concentrations of free radicals in the gas phase. I n the work reported here propane was nitrated and oxidized in molten salt and tubular reactors. The results help clarify the mechanisms of both reactions.
Experimental Nitration Runs in T u b u l a r Reactors. Propane from the cylinder (see flowsheet) was metered with a rotameter, and a safety flask prevented nitric acid from backing up in the system. From the safety flask, the propane bubbled through nitric acid flask heated with an electric heating mantle. The acid vaporization rate was controlled by manually adjusting the acid temperature to 95' zk 2' C., which gave a propane to acid ratio of about 6 to 1. The exact
222
borosilicate
amount of acid used was determined from the weights and specific gravities of the acid at the beginning and end of a run. The propane flow bypassed the nitric acid flask before and after a run. The mixture of propane and nitric acid was preheated in the preheater filled with a molten mixture of sodium and potassium nitrates maintained at 300" + 15' C. The preheater coil was constructed from a 4.5-foot length of 6-mm. borosilicate glass tubing. T h e hot gases from the preheater next flowed to the reactor. The four tubular reactois were constructed of borosilicate glass. Type 304 stainless steel, plain carbon steel, and copper. Each reactor had an inside diameter of about 11 mm. and a volume of about 250 cc. During a run the reactor being used was immersed in a molten mixture of potassium and sodium nitrates. The salt temperature was manually controlled to within 3' C. by means of electrical resistance wire wound around the bath. Because the Reynolds numbers of the gases in the reactor were calculated to be 700 or greater in all runs, the heat transfer characteristics were probably fairly good, and temperature differences between the gases and the molten salt were probably low. The residence times of the gases in the reactor were calculated on the assumption that the gases were ideal and at bath temperature and that there were no changes in the number of moles in the reactor. The ieactor pressures as measured by manometers were in all cases essentially atmospheric. The reactor effluent gases were passed in series through an air cooler, a watercooled spiral condenser, and a n icecooled condenser. The product receiver located at the bottom of the condenser contained 70 ml. of saturated
INDUSTRIAL AND ENGINEERING CHEMISTRY
sodium bisulfite solution to neutralize excess acid and to remove aldehydes by forming addition compounds. A liquid layer consisting primarily of nitroparaffins formed on top of the water layer as a run progressed. The gases which did not condense in the product flask passed to a series of three traps immersed in an acetone bath maintained at about -35' C. The volume of the exit gases from the traps was measured with a wet gas meter, and the gases were then exhausted. The exhaust gases were analyzed during runs with a conventional Orsat gas analyzer. At the end of the I-hour runs, the liquids in the product flask and cold traps were added to a separatory funnel. Small amounts of saturated sodium chloride solution, which were used to rinse out the product flask and traps, were also added to the separatory funnel. The water layer from the funnel \vas batch fractionated in a glass distillation column containing 30 plates until the bottoms temperature was at least 100" C. and until 3 to 5 ml. of water plus, in most runs, about 5 to 10 ml. of organic material had accumulated in the overhead condenser. The overhead product was added to the separatory funnel for the final separation of the two phases. The final organic layer was drawn into a tared sample bottle and weighed. A few gxams of calcium chloride was added to the product as a desiccant before the molecular weight was detei mined by a Victor Meyer vapor density method. Commercial propane (95% pure) and 70% nitric acid [Baker and Adamson) were used in this series of runs. Oxidation Runs in Molten Salt Reactor. The oxygen and propane from cylinders were metered and mixed before entering the molten salt reactor (shown). The reactor shell, constructed from 2-inch (inside diameter) borosilicate glass pipe about 40 inches long, was sealed shut a t the bottom, and the top end was equipped with an aluminum flange and steel cover plate. The reactor was partially filled with a n equal weight mixture of potassium and sodium nitrates. The reactor shell was wrapped with '/S-inch Xichrome heating ribbon, and a Variac variable transformer was employed to control the voltage to the ribbon. A Glass-Col heating mantle served as a support and heat source for the bottom of the reactor. A 75-mm. (outside diameter) glass tube was slipped over the reactor shell and heating ribbon to provide insulation. The gases to the reactor entered through an 8-mm. (outside diameter) glass tube passing through a packing gland in the top steel plate and extending below the surface of the salt. They were dispersed into the molten salt by either a sintered-glass bubbler or a n inlet tube with several small holes
PROPANE OXIDATION AND NITRATION Molten salt reactor for oxidation runs b was constructed of glass pipe and partially filled with a mixture of potassium and sodium nitrates
(about 1/3J inch in diameter) at the end. Four thermocouples were provided in the thermocouple well; the three located a t various depths below the salt level always read within at least 1 O C. of each other; and one thermocouple which could be adjusted to various levels was positioned above the salt level. The average pressure of the gases in the salt was assumed to be the average of the inlet and the outlet pressures, and it was just slightly above atmospheric. IVhen the gases bubbled through the salt the salt level increased; the volume increase of rhe salt bath was equal to the volume of gas bubbles in contact with the salt. The residence time of the qases in the salt was calculated assuming that the gases were ideal and a t bath temperature and that the number of moles of gas did not change in the reactor. The gases, aftrr leaving the salt, flowed upward throuqh the side outlet line, and then passed through an air cooler, an ice-cooled condenser and receiver, and a second condenser cooled to about -35" C. The noncondensed gases were metered, analyzed with a n Orsat gas analyzer, and exhausted. Il'hen any liquid product was obtained, it was analvzed for peroxides (7, 27) and aldehydes (5,27). The propane (99y0pure) employed was obtained from Phillips Petroleum Co. Commercial grade oxygen was used, and the potassium and sodium nitrates were C.P. grade. Nitration Runs in Molten Salt Reactor. The reactor employed (6) differed from the one shown in that it was constructed with a stsinless steel
0
K
OUTER
SHELLY
THERMOCOUPLE WELL-
q\,
GLASS
0 COPPER
,
A STAINLESS STEEL CARBON STEEL 0 COPPER I I
,
z
0
I
2
3
4
5
6
7
HOURS OPERATED
Conversions of 35% viously reported
were higher on a relative basis than those pre-
Figure 2. Relative nitration conversions were calculated by dividing nitroparaffin conversion in the metal reactor by conversion in the glass reactor at the same temperature VOL. 52, NO. 3
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1
V"
84
-
82
-
80
-
/1.0
-4.3
86 -
GLASS A STAINLESS STEEL
Q
00 a u E k z
18.0 16.0 14.0-
a
PROPANE /OXYGEN RATIOS: 4.3/1.0 AND 2.5/1.0 I
l
l
1
I
I
I
I
I
I
I
I
I
I
I
-
TEMPERATURE OC. Figure 3. Molecular weights of crude nitroparaffins from glass and stainless steel tubular reactors
Figure 4. Nitration conversions in molten salt reactor with oxygen added
Only two runs In the copper reactor produced sufficient product for molecular weight measuremeni
Temperature for optimum conversions was lower than in tubular reactors but similar to that in previous molten salt reactor experiments
shell. The shell was heated in all cases several inches above the salt level, and a water-cooled metal coil was installed in the gas space above the molten salt. The feed gas arrangement to the reactor was the same as previously reported (6) except both propane and oxygen were metered and mixed before bubbling the mixture through hot nitric acid (the arrangement was similar to thar shown in the flowsheet). The processing of the exit gases and nitroparaffins was similar to that described for the tubular reactors Results Nitration Runs in Tubular Reactors. Table I summarizes some of the operating variables for the runs in the four tubular reactors, and the conversion results for the glass, carbon steel, and copper reactors arc zhown in Figure 1. Considerable difficulty was obtained in gctting reproducible results in the two metal reactors, and the run numbers are shown on the drawing. The conversions in the carbon steel reactor became progressively better with time, and conversions in Runs 36 and 37 were, within experimental accuracy, the same as those for the glass reactor. At the end of Run 37, the steel reactor was disconnected from the apparatus for several days and was exposed to the air. When it was reconnected to the apparatus for Run 40, the conversion of that run was poorer than that of similar
runs in the glass reactor The conversions in the copper reactor were much lower than those in the glass reactor, and, fkrthermore, they became progressively worse until practically no product was formed. In the stainless steel reactor, conversion for the first run was essentially the same as for a comparable run in the glass reactor, but the conversions became progressively poorer with time. Relative conversions (Figure 2) were calculated by dividing the nitroparaffin conversion in the metal reactor by the conversion in the glass reactor, as g i v u in Figure 1, at the same temperature. The molecular weights of the nitroparaffin products obtained in runs in the glass and stainless steel reactors are shown in Figure 3. 'The molecular weights of the product obtained in the plain steel reactor were between 78.0 and 80.1 for Runs 31 to 37 and was 76.1 for Run 40. Sufficient product was obtained in only two runs in the copper reactor to enable measurement of the molecular weight. I n Runs 27 and 29, the values measured were 68.1 and 52.7, respectively, but insufficient material was available to check these values. As the molecular weight of nitromethane is 61, some materials other than nitroparaffins were in this product. Conversions of 35%, as shown in Figure 1, were higher on a relative basis by 15 to 20% than those previously reported for similar reactors (4, 8).
Table 1.
Contact Times and Mole Ratios for Nitration Runs in Tubular Reactors Av. Av . Deviation Deviation No. of Av. Contact of Contact Av. Mole of Mole Reactor Expts. Time, Sec. Time, % Ratio Ratio, % 8 1.43 12.2 5.62 15.7 Borosilicate glass T y p e 304 stainless steel Carbon steel Copper
224
7 8 4
1.41 1.44 1.52
INDUSTRIAL AND ENGINEERING CHEMISTRY
k1.6 11.9 zk2.8
5.81 6.26 6.21
14.1 *9.4 11.7
'The recovery techniques employed in this study were different, and some materials other than nitroparaffins may have been obtained in the products; however, some distillation losses (8) or extraction losses (4)may have occurred previously. Conversions of 357, or even higher are moreover apparently obtained commercially by Commercial Solvents Corp. (7Q), and the nitroparaffin conversions of this investigation are considered to be accurate within 1Oyc (on a relative basis). Oxygen-Induced Nitration Experiments in a Molten Salt Reactor. The conversions of nitric acid to nitroparaffins in a molten salt reactor when oxygen was added to the reactants are shown in Figure 4. Expeziments were made at a propane-oxygen ratio of about 4.3, with a ratio of propane to nitric acid of approximately 6, and also at a propane-oxygen ratio of 2.5, with a ratio of propane to nitric acid of about 13, except for the run at 414' C. which had a ratio of 5.2. The residence times of the gases in the salt varied from 1.2 to 1.7 seconds, but they were generally less than 1.5 seconds. The temperature for optimum conversions was definitely lower than that in the tubular reactors but similar to temperatures found previously in the molten salt reactor (6, 77). This temperature difference between the molten salt and tubular reactors is probably caused in part, a t least, by differences in temperature control of the gases. Several nitration runs were made using no oxygen, and the nitroparaffin conversions were similar to comparable runs of Coldiron (6). The conversions obtained here using oxygen were slightly lower than obtained by Coldiron, who used no oxygen, and by Hill (77), who rnade exploratory runs in the molten salt reactor using oxygen. The gas bubbles obtained in this investigation
PROPANE O X I D A T I O N AND NITRATION were, however, probably slightly smaller than those of the other two studies. However, oxygen does not significantly improve nitration conversion in the molten salt reactor as it does in tubular reactors; rather, it appears to decrease conversions slightly in most cases at least. The nitroparaffin conversions in the molten salt reactor are low (a maximum of about 24%) in comparison to the conversions (up to 35Yc) in the tubular reactors. The recovery system employed with the molten salt reactor only cooled the exit gases to about 0" C. compared with about -35" C. in the case of the tubular reactor; however, the amount of nitroparaffin that did not condense at 0" C. was calculated by use of Dalton's law assuming that the partial pressurr of thr nitroparaffins in the gas stream was equal to the vapor pressure of the nitroparaffins ai. 0" C. The conversions in the molten salt reactor were corrected for the calculated amount of noncondensed nitroparaffins, and these conversions were significantly lower than those found in the tubular reactor. The nitroparaffin products obtained by using oxygen ill the feed to the molten salt reactor had molecular weights ranging from 73 to 80 and were appreciably lower than those obtained in the molten salt reactor without oxygen (6). Oxidation Runs in Molten Salt Reactor. Preliminary oxidation runs in the apparatus of Coldiron ( 6 ) demonstrated that partially oxygenated products including peroxides and aldehydes were obtained when the feed mixtures had a propane to oxygen ratio ranging between 1.1 to 1 and 4.3 to 1. Because the walls of the reactor were heated above the level of the salt in the reactor, the location of the reaction could not be determined precisely. As a result the reactor shown was built and operated for the remainder of the oxidation studies. This glass reactor had the advantages of better temperature control and, in addition, allowed visual observations of the bubble size and the salt level. The first series of oxidation runs in the molten salt reactor was made over the following range of operating variables: Propane-oxygen ratio Molten salt temp. Pressure Residence times in salt Av. bubble size
1.5-1 up to 3.68-1 320-408O C. 1 atm. 1.1-6.8 seconds 3/1a-3/8
in.
Although these operating variables are in the range in which the low temperature partial oxidation reaction would be expected, no measurable reaction was obtained as in.?i.cated by the carbon oxides and oxygen analyses with the Orsat gas analyzer. Furthermore, no liquid product was obtained even in the
-35" C. cold traps. The salt surface apparently completely suppressed the low temperature reaction. Small quantities of copper and nickel nitrates were added to the molten salt, as these salts might catalyze the oxidation reaction. These salts decomposed at the surface of the salt bath to release nitrogen oxides and to form black dispersions, apparently oxides, in the bath, which made no noticeable changes in the oxidation results . Because no oxidation had occurred ar the conditions where a reaction would be expected, two nitration runs were made tci check the reactor. Although the nitration conversions were not determined precisely, an appreciable amount of nitroparaffin product was obtained when mixtures of propane and nitric acid were fed to the reactor. The reactor is hence satisfactory for nitration. The next series of oxidation runs consisted in heating the 2-inch glass pipe for several inches above the level of the molten salt. As a result, the gases leaving the salt were maintained at reaction temperatures, and the piping above the salt eisenrially became a tubular reactor. Several runs were made with a salt bath temperature of
about 400" C., and the gases leaving the salt were maintained at temperatures above 320' C. for about G to 9 seconds. I n these runs, the Orsat gas analyses indicated oxygen conversions up to at least 55%, and appreciable quantities of aldehydes and peroxides were condensed iron1 the gas stream. Although no effort wa+ made to analyze the product stream completely, the products obtained were apparently typical of the low-temperature oxidation reaction of propane, and the reaction probably occurred in the heated space above the salt bath. The final series of oxidation runs was made at a propane to oxygen ratio of 3 to 1 and with molten salt temperatures up to 510" C. The glass piping above the salt was not heated in these runs so that the gases leaving the salt cooled rapidly. The Orsat anall-ses of the exit gases were plotted as a function of the reactor temperature for a residence times of about 6.0 and 4.5 seconds (Figure 5). Detectable reactions first occurred at 6 seconds at about 420' C. and at 4.5 seconds at about 450" C. A run was made at 500" C. and at a contact time of 2.0 seconds, but no detectable reaction was observed in thir rdse.
P
81
420
440
a
I -
m
I
460
-tOXY-GEN
O
500
180
-
12
8 I
A /
..
0
400
440
420
460
500
480
REACTOR TEMPERATURE,"C.
Figure 5. Composition of product gas for oxidation runs in molten salt reactor Carbon monoxide content of exit gases was essentially zero in all cases A.
6.0 seconds
6.
4.5 seconds
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In all cases the carbon monoxide content of the exit gases was essentially zero. At higher oxygen conversions some liquid product was obtained in the cold traps, but aldehyde and peroxide tests of the liquid were negative. Apparently the liquid was essentially water. The products obtained indicate that the reaction was not the low-temperature type but rather was of the high-temperature type that produces carbon dioxide, olefins, and water.
Discussion
The results of the present investigation are helpful in explaining the effect of surface on both the vapor phase oxidation and nitration reactions of propane. The suppression of the lowtemperature oxidation reaction in the molten salt reactor is of major interest. Salts have long been recognized as being highly effective in destroying free radicals. Because the surface to volume ratio of the gases bubbling upward through the salt was high, it might be reasoned that free radicals formed in the gas phase were quickly destroyed at the surface, stopping the chain reactions before a measurable oxidation reaction could occur. Such reasoning is, however, probably incorrect, as the nitration reaction proceeded satisfactorily in the molten salt. Free radicals of that reaction would presumably be destroyed a t the surface about as readily as those of the oxidation reaction; in fact, several radicals includinq alkyl and hydroxyl radicals are common to both reactions (7, 8, 75, 27, 22). I t could also be postulated that the induction time to obtain an appreciable concentration of free radicals for the oxidation reaction was significantly increased in the salt reactor so that the induction period was longer than the residence time investigated. Because the conversions of the oxygen-induced nitration runs in the molten salt reactor were no higher than those not employing oxygen, apparently the oxygen was ineffective in generating additional free radicals, even though an appreciable concentration of free radicals must have been present. The failure of the oxygen to form increased quantities of free radicals in the nitration reaction was not then caused by a long induction period, and a long induction period also probably does not explain the failure to obtain a low-temperature oxidation reaction in the molten salt reactor. I t is postulated that a suitable surface is required for an initiating step of the low-temperature oxidation reaction, and the molten salt did not provide such a surface. Presumably at least one of the reactants must first be sorbed, followed later by a surface reaction. As the temperature increases, the amount of
226
sorbed material will probably decrease, but the reaction rate constants of the surface reaction will increase. The combination of these two factors can explain the negative temperature coefficients of the oxidation reaction (75, 78). Because the high-temperature oxidation reaction occurred in the molten salt reactor, the initiating steps of this reaction were apparently occurring in the gas phase. The long induction times of the reaction in the salt reactor were probably caused by the relatively rapid destruction of free radicals at the salt surface. Future studies are being planned in which larger gas bubbles in the salt will be employed to test this hypo thesis. I n the nitration runs in the molten salt reactor in which oxygen was employed, the oxygen did enter into the gas phase reactions, as the molecular weights of the nitroparaffins produced with oxygen in the feed were less than those obtained in runs without oxygen. Two mechanisms have been proposed for the vapor phase nitration of paraffins. The first one consists of the following three 1 eactions (7) : HNOi RH
+
HO.
+ .OH
R.
f.
+
+ *NO* R . + HzO
KO2 -L RNOQ
(1) (2) (3)
This mechanism is open to question, however, as the rate of nitroparaffin formation is greater (3, 4, 6, 8 ) than the rate of decomposition of nitric acid, as shown in Equation 1 (73). The second mechanism (8, 76), which is preferred, consists of Equations 1 and 2 plus Equation 4: R*
+
“ 0 3
-L
RNO2
+ *OH
(4)
Equations 2 and 4 involve a chain reaction, so the rate of nitroparaffin formation can be faster than that for the thermal decomposition of nitric acid. Because nitration runs proceeded smoothly in the molten salt with fairly good conversion, the initiation and propagation steps of this reaction were apparently occurring in the gas phase. The difference in nitration conversions between the various tubular reactors and the molten salt reactors is explained by the effectiveness of the surface in destroying free radicals. Previously increased surface to volume ratios had been shown to decrease nitroparaffin conversions (2). Thus, the molten salt reactor is quite effective in destroying free radicals, and this type of reactor should prove valuable as an experimental tool. Oxidation products often increase as the nitration conversions decrease, and apparently the surfaces formed when thestainless steeland copper reactors were used are oxidation catalysts. In the case of the carbon steel
INDUSTRIAL AND ENGINEERING CHEMISTRY
reactor, however, oxidation catalysts on the surface are apparently destroyed with time. More studies on this subject are necessary to evaluate these surface changes. Glass surfaces, on the other hand, do not seem to change as a function of time. Acknowledgment
Alexander Sesonske helped direct the research pertaining to the nitration of propane in tubular reactors: and J. Vincent Dardin offered many valuable suggestions. Celanese Corp. provided a fellowship for the phase of the project in which propane was nitrated in the molten salt reactor. Phillips Petroleum Co. furnished the propane used. literature Cited
(1) Bachman, G. B., Addison, L. M., Hewett, J. V., Kohn, L., Millikan, A , , J . Org. Chem. 17, 906 (1952). (2) Bachman, G. B., Atwood, M. T., Pollack, M., Zbid., 19, 312 (1954). (3) Bachman, G. B., Hass, H. B.? Addison, L. M., Zbid., 17, 914 (1952). (4) Backman, G. B., Pollack, M., IND. ENG.CHEM.46, 713 (1954). (5) Brocket, A., Cambier, R., Comfit. rend. 120, 449 (1894). (6) Coldiron, D. C., Albright. L. F., .4lexander, L. G., IND.ENG.CHEM.50, 991 (1958). (7) Dickey, F. H., Raley, J. H., Rust, F. F., Treseder, R. S., Vaughn, W. E., Ibid., 41, 1673 (1949). (8) Hass, H. B., Alexander, L. G., Ibid., 41, 2266 (1949). (9) Hass, H. B., Dorsky, J., Hodge, H . B., Zbid., 33, 1138 (1941). (10) Hass, H. B., Patterson, J. A , , Zbid., 30, 67 (1938). (11) Hill, R. D., M.Ch.E. Thesis, University of Oklahoma (1952). (12) Hoare, D. E., Walsh, A. D., “Fifth Symposium (International) on Combustion,” pp. 467-74, Reinhold, New York, 1956. 3) Johnson, H. S., Foering, L., Thompson, R. J., J . Phys. Chem. 57, 390 (1953). 4) King, R. O., Sandler, S., Strom, R., Canadian J . Chem. Enx. 35, NO. 6, 33 (1957). 5) Lewis, B., Von Elbe, G., “Combustion, Flames and Explosions of Gases,” Academic Press, New York, 1951. 6) McCleary, R. F., Degering, E. F., IND.ENG.CHEM.30, 64 (1938). 7) Martin, J., U. S. Patent 2,260,258 (Oct. 21, 1941). 118) Pease, R. N., J . A m . Chem. SOC. 60, ’ 2244 (1938). (19) Petrol. Refiner 36, No. 11, 267 (1957). (20) Satterfield, C. N., Reed, R. C., “Fifth Symposium (International) Combustion,” p. 435, Reinhold, New York, 1956. (21) Satterfield, C. N., Wilson, R . E., LeClair, R. M., Reid, R. C., Anal. Chem. 26,1792 (1954). (22) Satterfield, C. N., Wilson, R. E., Stein, T. W., Cooper, D. O., IND.ENG. CHEM. 46, 1001 (1954). ’
RECEIVED for review May 14, 1959 ACCEPTED December 7, 1959 Division of Industrial and Engineering Chemistry, 136th Meeting, ACS, Atlantic City, N. J., September 1959.
