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1986,2 5 , 508-514
Thermolytic Reactions of Dodecane Pelrheng Zhou and BHly L. Crynes’ School of Chemical Engineering, Oklahoma State University, Stillwater, Oklahoma 74078
Dodecane thermolysis was investigated under moderate temperatures and high pressures of N, or H., Dodecane is stable below 600 K, whereas under severe conditions it is thermolyzed to give a series of paraffins and olefins up to C2*but with CI3missing. High reaction pressure favors the formation of saturated hydrocarbons and shifts the product distribution toward heavier components. The yield of paraffin plus olefin of the same carbon number decreases with increasing molecular weight, and the yield of the olefin is slightly higher than that of its paraffin counterpart. These observations can be satisfactorily interpreted by a free-radical-chain mechanism with certain modifications. Hydrogen participates in dodecane thermolysis through radical-capping reactions. The pseudofirst-order rate law applies to dodecane disappearance.
In our laboratory, dodecane was used as a carrier solvent for kinetic studies of certain compounds because of its reasonably high boiling point, critical temperature, and thermal stability. This solvent was also employed by other researchers, but its thermal stability has never been fully assessed. The objective of this work was to characterize dodecane thermolysis under moderate conditions and at low conversions. Attempts were also made to work out the kinetics and a reaction network mechanism. This study contributes information to not only solvent behavior of alkanes but also thermolysis characteristics of highermolecular-weight aliphatic hydrocarbons. The thermal cracking of alkanes has been a subject of study for over half a century. Most of the work involves light paraffins (Back and Back, 1983; McConnell and Head, 1983; Corcoran, 1983), whereas heavy ones with carbon numbers greater than eight have received little attention. Only a few examples of thermal cracking of heavy hydrocarbons are documented in the literature, mostly of hexadecane. Voge and Good (1949) were among the earliest to study thermal cracking of hexadecane and an isododecane, at a temperature of 773 K and under low pressure (atmospheric to 2.1 MPa). Greensfelder and Voge (1945) reported a dodecane-cracking experiment at 823 K, but no liquid product composition was available. Hexadecane cracking was again investigated by Fabuss et al. (1962, 1964) under pressures up to 7 MPa and higher temperatures of 866-977 K. A detailed study of pressure effects on hexadecane pyrolysis was performed by Doue and Guiochon (1968a,b, 1969). A flow method was described by Groenendyk et al. (1970) for hexadecane thermolysis which provides a qualitative analytical technique for the identification of gas chromatographic effluents. Recently, Rebick (1981) and Mushrush and Hazlett (1984) also reported some data on hexadecane pyrolysis. Freeradical mechanisms have been shown by the authors, and first-order kinetics was obtained or adopted. Comparison between observed and predicted products by the radical-chain theory gave good agreement (Voge and Good, 1949; Rebick, 1983). The reaction conditions in our study were directed toward relatively low severity because of our interest to use dodecane as a solvent. The confounding effects of the reaction products of the solvent on other reactants were sought. *To whom correspondence should be sent. 0196-4305/86/1125-0508$01.50/0
Experimental Section All thermolytic reaction experiments of dodecane were conducted in a batch reactor system with an autoclave of 0.001-m3capacity. A schematic diagram of the apparatus is shown in Figure 1. The feed (0.3-0.4 kg) was loaded in the reactor which, after purging thoroughly with the appropriate gas (N2 or HJ,was rapidly brought to the desired conditions. The reactor system was maintained under constant temperature (within 1 K) and pressure (*0.07 MPa) during the experimental interval. Initial and successive gas and liquid samples were collected at scheduled time intervals. After the final sample was taken, water was introduced into the internal cooling coil to quench the reaction. A glass liner was used to minimize the possible catalytic effect of the metal reactor wall. A stirrer, vertically situated in the center of the reactor, operated at 30 000 rph during the reaction. Mixing experiments showed that homogeneity was achieved in the liquid phase inside the reactor. Dodecane (Fisher Scientific purified grade, as received) was thermolyzed at temperatures from 523 to 713 K and system pressure of 9.2-10.3 MPa, either in N2or H2 (Union Carbide, Linde Division, prepurified specialty gas grade N2 and ultra high purity grade HJ. Both gas and liquid samples were analyzed by gas chromatography (GC) and selected samples by GC/mass spectrometry. The GC columns and conditions adopted for routine analysis are shown in Table I.
Results Preliminary experiments on dodecane thermolysis, conducted under 10.3-MPa nitrogen pressure and increasing temperature, showed that a t temperatures lower than 620 K, for a period less than 2 h, dodecane conversion was less than 0.3 wt %. Typical results from four experimental runs (with two consistent replicates) a t 623 and 673 K, 9.2 MPa, in the presence of N2 and Hz, are shown in Figures 2-4 (liquid analyses) and 5 and 6 (gas analyses). For runs carried out a t 623 K and 9.2-MPa N2, for a reaction time of 6.67 h, the thermal conversion of dodecane was 1.3 mol % , while at 673 K, same system pressure for 5 h, about 35 mol % of the reactant was converted. Even the low conversion of around 1% will bring some influence on the reaction behavior of certain solutes when dodecane is used as a carrier solvent; this will be discussed in another article. Dodecane conversions under various conditions are plotted in Figure 7. 0 1986 American Chemical Society
Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986 509
Table I. Gas Chromatographic Analysis analysis column hydrocarbon gas Porapak Q, mesh 100/120 4 X 0.0032 m hydrocarbon liquid (routine) 1%SP-1240DA on Supelcoport, mesh 100/120, 2 X 0.0032 m hydrocarbon liquid (check) Carbowax 20 M on Chromosorb W H/P, mesh 80/100, 2 X 0.0032 m
detector temp program flame ionization 433 K isothermal flame ionization 60 s at 313 K, 313-453 K at 0.17 K/s, 600 s at 453 K flame ionization 180 s at 313 K, 313-415 K at 0.17 K/s, 600 s at 453 K
It! 00
VENT
t
.TT
2
-i
w?
n
80
-a r
70 t!
60
4
0
6.0
12.0
18.0
REACTION TINE ( S M O - ~
SAMPLE
Figure 3. Product distribution of dodecane thermolysis (T= 673 K, P = 9.2 MPa, N2).
Figure 1. Batch autoclave system.
0,2 N -I 0
E
z
0.1
6 0
Gn B
n.
n -0
-
-
6.0
12.0
18.0
24.0
REACTION TIME ~ ~ 1 0 - 3
Figure 2. Product distribution of dodecane thermolysis (T= 623 K, P = 9.2 MPa, N2).
Reaction products of dodecane thermolysis can be divided into two groups: those with molecular weights lower than that of the reactant, the decomposition products, and those with more carbon numbers than dodecane, the combination products. The latter are lumped together and
REACTION TINE ~ ~ 1 0 - 3
Figure 4. Product distribution of dodecane thermolysis (T = 623 K, P = 9.2 MPa, HJ.
shown as >Clz in the figures. The thermal reactions of dodecane, under these conditions, produce a range of hydrocarbons from methane up to CZ2,which is the heaviest component identified by
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Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986
T 1 I -I -
0
0
5
m
I=
U
B O
o 0,20
FEACTION TIE (~)~10-3 Figure 10. Paraffins and olefins from dodecane thermolysis (T= 673 K, P = 9.2 MPa, N2).
no olefins are found in the gas samples obtained from the run conducted in the hydrogen environment. Under otherwise identical conditions (623 K, 9.2 MPa), the presence of molecular hydrogen apparently reduces dodecane conversion from 1.3 to 1.0 mol 5%. Comparison between individual products from dodecane conversion in the presence of N2 or H2 (Figures 11 and 12) shows that both the light ends (SC,)and heavy ends (XI,) from the run in H2 are lower in yield. The difference in the latter is obvious. The formation of the rest of the liquid products is essentially the same in both environments. No carbon formation was observed in the experimental runs. Liquid samples and the remaining liquids in the reactor after reaction were clear to faintly yellow in color. Discussion For all experiments reported here, material balances better than 96 w t % were obtained. The average gas plus
0.10
r
0
"
"4--,
6,O
12,o
I
18.0 REACTION TIME ( ~ ~ 1 0 - 3
24.0
Figure 12. Product3 from dodecane thermolysis in different environmenk (T= 623 K, P = 9.2 MPa).
loss is 3.3 w t 5%. The gas makes amounts of about 0.1 (623 K run) to 3.0 wt % (673 K run) of the feed. The loss is mainly due to slight splashing during the line purge before sampling and minor gas leakage during the run. This would not significantly affect the composition of the sample and hence the conversion and yield data. In spite of careful purging of the sampling lines before each collection of sample, a slight amount of liquid attached to the tube walls is possible and may be the cause of some data error. The confidence limits for liquid analysis data are within fl%, while those of gas analysis data are within *lo%,
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Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986
as restricted by the accuracy of the calibration gas standards. Error analysis shows an average deviation of 23% for the kinetic constants presented. Since the reactor wall was covered by a glass liner, the only metal surface exposed to the reactants was from a small stainless steel stirrer and part of the cooling coil, which was about 1/5 of that of the reactor wall. The reaction system therefore has a small, exposed, surface-tovolume ratio; moreover, the ratio of the surface to the mass of reactants of this system is also small due to the high reaction pressure employed. Consequently, kinetic differences due to the surface influence are not expected in this study. Because of the low conversion (623 K runs) and long reaction period (5-7 h), heat effects of both chemical and physical changes inside the reaction system are not great enough to cause heat-transfer problems. Estimation has been made regarding possible masstransfer limitation of hydrogen at the gas-liquid interface in the reactor. As discussed later, the principal effect of hydrogen is considered to be the suppression of the coupling reactions and stabilization of the free radicals. With reference to the product analyses, the difference in the yields of the saturates between the runs in the presence of Nz or H2 is estimated to be 10 mol per 100 mol of converted dodecane. This is roughly equivalent to 0.003 mol of hydrogen consumed. The solubility of hydrogen was estimated, from the work of Sebastian et al. (1980),to be equivalent to about 0.5 mol of hydrogen dissolved in the liquid phase of our system, which is hundreds of times the estimated hydrogen consumption. Evidently, the mass transfer of hydrogen was not a limiting factor for those runs. We therefore feel confident to say that the thermolytic reactions of dodecane in this study are within the kinetic region. The high value of the activation energy presented in the following section supports this argument. I. Reaction Kinetics. Simple rate equations with the reaction order varying from 0.4 to 2.0 were tested for the experimental data of dodecane conversion, and a pseudo-first-order rate law applies best. The following data are obtained for dodecane disappearance under a nitrogen pressure of 9.2 MPa k623 = 4.7 x
S-'
E , = 273 kJ/mol and A. = 3.7
X
10l6
where k,,, and k673are rate coefficients for dodecane disappearance at 623 and 673 K, respectively, E , is the activation energy, and A. is the frequency factor. A less-reliable value of k713 = 10 X s-l, estimated from only two data points, is given for reference. The solid curves in Figure 7 are regression lines based on first-order kinetics, which show good agreement with the experimental data. Under a hydrogen atmosphere, the conversion is somewhat lower; and therefore a lower value of rate coefficient is obtained: Pyrolysis of heavy paraffins is generally first-order in the reactant (Voge and Good, 1949; Fabuss et al., 1962, 1964; Doue and Guiochon, 1968a,b, 1969; Groenendyk et al., 1970; Rebick, 1981, 1983). Our work shows that do-
decane thermolysis is not an exception. The only rate coefficient for dodecane cracking was reported by Voge and Good (1949) for conditions of 823 K and atmospheric pressure in a flow system. Van Camp et al. (1984) calculated a pyrolysis rate constant for dodecane in a kerosene fraction at 1073 K based on pilot plant flow reactor data. We do not think it appropriate to extrapolate our data, which were taken under completely different conditions, for comparison. The observed activation energies for first-order reactions of heavy paraffin pyrolysis are in the range of 250 f 20 kJ/mol (Rebick, 1983). A value of 250 kJ/mol is obtained by Groenendyk et al. (1970) for the activation energy of hexadecane thermolysis (790-862 K). Our E, value compares well with these data, although at the upper end. No frequency factor values for dodecane cracking are recorded. However, data suggest that A factors in bond fissions (of large groups) not developing resonance in the transition state are consistently in the range of s-l (Richardson and O'Neal, 1972). The preexponential factors for methane, propane, and butane pyrolysis have been reported in this range (Powers and Corcoran, 1974; Zaslonko and Smirnob, 1979; Pratt and Rogers, 1979). The A factor value for dodecane thermolysis achieved here is, therefore, reliable in view of the rarity of external references. 11. Product Distribution. Unlike the case of hexadecane cracking at low pressures, a large amount of alkanes larger than propane are found in dodecane thermolysis products in our experiments. This is undoubtedly related to the high pressure used in this study, which shifts the selectivity toward heavier hydrocarbons, as in the case of hexadecane cracking under a relatively high pressure (6.9 MPa) which decreased the selectivity to light hydrocarbons (Fabuss et al., 1962). The decrease in product yields with increasing molecular weights, as observed in our experiments, can also be seen from the data of Fabuss et al. (19621, Rebick (19811, and Mushrush and Hazlett (1984). This phenomenon can be explained by the difference in dissociation tendencies of different-sized radicals, as shown later. Higher pressures also make products which are more saturated in nature. In our products, alkanes are much more abundant than reported for hexadecane cracking under low pressures but are still less than their alkene counterparts. At low pressures, Greensfelder and Voge (1945) found 83% olefins in the 373-483 K fraction of hexadecane thermolysis (823 K), while a t about 15 MPa Doue and Guiochon (1968) obtained equal amounts of paraffins and olefins. As a rule, the higher the reaction pressure is, the more saturated are the products from paraffin cracking. The product distribution is also dependent upon cracking severity. Data in Table I1 show that higher conversion shifts the distribution toward lighter hydrocarbons, which is consistent with the observation of Mushrush and Hazlett (1984) in hexadecane thermolysis. As mentioned earlier, C13 is missing and Cz2 is the heaviest compound in dodecane thermolysis products. According to Fabuss and co-workers (1962), analysis of the residue (>c16)obtained in hexadecane cracking showed that most of this material was paraffin and nearly all was in the Cu-Cz0 range. In both cases, hydrocarbons with a carbon number one more than that of the reactant were absent. This may not be a mere coincidence and will be discussed in the mechanism to be proposed. Fabuss et al. (1962) also observed a large amount (25 wt 9'0 or more) of residues at low conversions (approximately
Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986
Table 11. Experimental and Theoretical Products from Dodecane Thermolysis (mol per 100 mol Converted at 9.2 MPa) 623 673 673 temp, K 623 623 reaction time, h 6.7 6.7 5.0 environment N, H2 N2 conversion, % 1.3 1.0 35.2 E" E To E T 0.2 0.01 3.2
5.6 1.5 13.1 25.6 14.4 19.6
4.0 0.4 12.5 4.0 15.6 34.8*
C6H14
CvH,, C;H;, C8H16
CBHlt? C9H18 C9H20
C1oHzo C10H22 C11H22 C11H24
>C12
14.2 10.1 8.9 5.8 9.7 5.9 6.5 4.7 3.8 1.6
14.2 9.9 11.4 7.3 9.0 7.3 6.8 6.0 3.7 1.5
2.7 16.2
0.5 14.6
14.1 14.0 12.9 10.6 9.3 9.9 7.9 9.9 1.2 4.4 0
14.3 12.6 7.3 4.1 3.7 3.2 2.6 0.9 0.2 0.3 21.7
6.1 1.9 13.6 26.8 15.3 20.8 14.4 13.6 15.3 14.9 13.9 10.8 7.6 9.9 4.9 9.8 0.2 4.4 0
IV. Reaction Mechanism. Thermal decomposition of paraffins invariably occurs by complex mechanisms involving free-radical-chain reactions. The following mechanism is suggested for dodecane thermolysis on the basis of the experimental results and the above discussion. Dodecane has a large number of degrees of freedom; the pressure used is high and the temperature relatively low. The initiation reactions in dodecane thermolysis are expected to be first order in nature n-ClzH26
n-CiHZi+l*+ n-CjH2j+i* (primary) (primary)
(1)
where the right-hand side are radicals with i = 1-6 and i j = 12. Hydrogen abstraction from dodecane molecules by these radicals is most probably the first step of the reaction chain n-C12H28 + R. n-C12H25*+ RH (2) where R. is any radical formed in reaction 1, and n-C12Hw. is to be understood as a radical derived from n-Clz by the removal of any one hydrogen atom. For the radicals obtained in the above reactions, pscission of the C-C bond dominates absolutely, but special attention is given to the radical formed via reaction 2, which can break up in two ways:
+
2
n-CllH22
c-c-c-
c-c-c-c-c-c-cc-c
E = experimental, T = theoretical. *Lower due to vaporization loss during analysis.
20%), and this steadily dropped with increased conversion. In our experiments in contrast, ever-increasing residue yields with increasing conversion were noted. There seems to be a maximum point for residue yield, which may be affected by temperature. For the work of Fabuss and collaborators, this maximum is likely at conversions lower than 20% and in our work at higher conversions. Since the activation energy for cracking is usually higher than that for bimolecular reactions, higher temperatures favor cracking reactions and would cause a shift of the maximum point for residue yield toward lower conversion. 111. Effect of Hydrogen. Study of thermal cracking of heavy alkanes in the presence of hydrogen is not known from the literature. Dodecane was thermolyzed in molecular hydrogen in contrast with nitrogen in this work, at the same temperature (623 K) and pressure (9.2 MPa). A test of the null hypothesis that the two runs (one in nitrogen and one in hydrogen) produced on the average the same conversion leads to a significance probability of C12fraction is decreased.
513
c1
+
CH3*
(3a)
n-C4H8 f P C ~ H , ~ * (3b)
(primary)
Ethyl radicals and those larger, such as the primary octyl radical formed in reaction 3b, possess resonance energy, while the methyl radical does not. This would give a difference in activation energy of 8.4 kJ/mol, making reaction 3b 5 times as fast as reaction 3a at 623 K. In the decomposition of the 1-ethylbutyl radical, the calculated ratio is 3 vs. the observed value of 2 (Kossiakoff and Rice, 1943). We take 3.5 for the case of 1-ethyldecyl radical decomposition. Another point is the fate of the radicals developed during n-Clz. decomposition. For example, the primary decyl radical generated can undergo two reactions: n-Clo (primary) n-Clz n-Clo + n-CIz. (4a)
-
+
-
-
n-Clo. (primary) C=C + n-Cg (primary) (4b) A t low pressure, radicals larger than ethyl are assumed to dissociate faster than they react with hydrocarbon molecules. As a result, many paraffin pyrolyses end up with methane, ethylene, and hydrogen; no paraffins are observed, even ethane. This is clearly not the case with this work. The lower temperature and higher pressure favor hydrogen abstraction in competition with radical decomposition, at least for smaller radicals. The single-step fragmentation model proposed by Fabuss et al. (1964b) for n-alkane cracking at high pressures results in approximately equal amounts of n-alkanes and 1-olefins of intermediate chain length, and the multistep model proposed by the same authors would result in more alkenes and shorter alkanes. Our approach adopts the coiling mechanism of Kossiakoff and Rice (1943) for the first radicals (n-C,zH,5.) of the chain, which undergo p-scission reaction. The radicals thus generated undergo isomerization to secondary radicals; then either cleavage to smaller olefins and radicals or intermolecular hydrogen transfer to alkanes and dodecyl radicals follows. The probabilities of these two options depend upon the radical sizes. From the correlations of cracking rate constants and carbon numbers of n-alkanes provided by Tilicheyev
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(1939), Voge and Good (19491, and Van Camp et al. (19841, we estimate the relative rate of cracking for n-C12/nCll/n-Clo/n-C9/n-C,/n-C7 N 24/20/15/10/5/1 under our conditions. Hence, we assume that radicals smaller than heptyl undergo decomposition only negligibly compared with their reaction with the n-C12molecule. For radicals larger than heptyl, decomposition is gradually weighted with increasing molecular weight of the radicals. Consequently, the product yields are calculated and listed in Table 11, together with the observed data. As a whole, the free-radical-chain theory with our modification gives results in marked agreement with the experimental data for dodecane thermolysis. Excellent consistency is obtained for C,-Clo hydrocarbons except for lower values of nonene and decene obtained than predicted for 673 K thermolysis. Conversion is therefore another factor influencing product distribution. Our model leads to a successful prediction of the fact that as an overall behavior, long-chain alkanes tend to crack at C-C bonds toward the center of the molecules, under moderate temperature and high pressure. The theoretical calculation gives more high paraffins than simple Rice theory does and also predicts more olefins than paraffins of the same carbon number larger than four, in satisfactory agreement with the observed data. This approach also correctly expects decreasing yields of paraffin plus olefin with increasing molecular weight. This mechanism also predicts low yields of methane and ethylene and high yields of ethane and propane, which the simple Rice mechanism would never do. However, it fails to predict low yields of propylene. According to Goldfinger and co-workers (1948), the termination should be p p in nature in dodecane thermolysis. Here, only the n-C12.radical can be considered a p-radical. Therefore, the chain termination steps for dodecane thermolysis are most probably induced by collisions between a dodecyl radical and another smaller radical. Owing to the small amount of methyl radicals produced and their tendency to escape into the gas phase, the smallest radical involved in the combination reaction with the dodecyl radical is then probably ethyl. This means that the smallest termination product would have a carbon number of 14, which explains the absence of CI3 hydrocarbons. Furthermore, large radicals such as undecyl dissociate much faster than they couple with dodecyl radicals; hence, the highest molecular product detected is not larger than docosane. Conclusion Dodecane is relatively stable as a carrier solvent to be used under mild conditions, such as below 600 K and less than 2-3 h. Pressure and concentration are not critical, while hydrogen suppresses its conversion. At higher temperatures and for longer reaction time, dodecane thermolysis becomes significant, and the solvent background should be taken into account. Dodecane thermolysis gives a range of products from C1 to C22,with C13absent. Under moderate temperatures, 623-673 K, and relatively high pressures, 9.2-10.3 MPa, the product distribution is completely different from those obtained by high-temperature, low-pressure pyrolysis of heavy paraffins. Ethane and propane are predominant in gaseous products, while methane and ethylene are low. Large amounts of higher paraffins with carbon atoms of more than three appear in the liquid products although their yields are still lower than their olefin counterparts. These cannot be explained by a simple Rice mechanism.
The thermolytic reactions of dodecane have a free-radical-chain mechanism with unimolecular initiation and termination. n-Clz. is the main carrier of the reaction chain, while termination most probably occurs between dodecyl and other radicals. Under conditions employed in this work, second-generation radicals formed through decomposition of the parent dodecyl radicals undergo first isomerization and then either hydrogen abstraction from dodecane molecules or further p-scission to form smaller products. The relative probabilities of these two options are determined by radical size and operating conditions. When these are taken into consideration, the statistical calculation of product yields agrees satisfactorily with the observed data. The shift of the product distribution toward heavier and more saturated products and the decreasing yields with increasing molecular weights of the components, as observed in our experiments and others, are well-explained. Apparently, long-chain alkanes tend to dissociate more at the C-C bonds toward the center of the molecules because larger radicals tend to crack more than to abstract hydrogen atoms. Hydrogen plays its role mainly by capping hydrocarbon radicals and suppressing coupling reactions, thus reducing unsaturates and residues to a certain extent. In the meantime, thermolytic conversion is also lowered. Pseudo-first-order kinetics applies best to dodecane thermolysis. The rate coefficients, activation energy, and frequency factor for dodecane thermolysis are obtained and are reasonable compared with the limited literature data. Acknowledgment Financial support for this work was gratefully received from Oklahoma State University, School of Chemical Engineering, and the University Center for Energy Research. Registry No. Dodecane, 112-40-3. Literature Cited Back, M. H.; Back, R. A. "Pyrolysis: Theory and Industrial Practice"; Academic Press: New York. 1983: Chanter 1. Corocran, W l H. "Pyrolysis: Theory~and Industrial Practice"; Academic Press: New York, 1983; Chapter 3. Doue, F.; Guiochon, G. J . Phys. Chem. I968a, 7 3 , 2304. Doue, F.; Guiochon, G. J . Chim. Phys. 1968b,6 4 , 395. Doue, F.; Guiochon, G. Can. J . Chem. 1989, 4 7 , 3477. Lait, R. I . ; Borsanyi. A. S.;Satterfield, C. N. Ind. Fabuss, E. M.; Smith, J. 0.; Eng. Chem. Process D e s . Dev. 1962, I, 298. Fabuss, E. M.; Kafesjiin, R.; Smith, J. 0.;Satterfield, C. N. Ind. Eng. Chem. Process D e s . Dev. I964a,3 , 249. Satterfield, C. N. "Advances in Petroleum ChemFabuss, B. M.; Smith, J. 0.; ical Refining"; Interscience: New York, 1964b. Goldfinger, P.; Letort, M.; Niclause, M. "Contribution a I'etude de la Structure Moleculaire"; Desoer: Liege, 1948; Victor Henry Commemorative Vol. Greensfelder, B. S.;Voge, H. H. Ind. Eng. Chem. 1945,3 7 , 517. Groenendyk, H.; Levy, E. J.; Samer, S.F. J . Chromatogr. Sci. 1970,8 , 115. Kossiakoff, A.; Rice, F. 0. J . Am. Chem. SOC. 1943, 6 5 , 590. McConneil, C. F.; Head, B. D. "Pyrolysis: Theory and Industrial Practice"; Academic Press: New York, 1983; Chapter 2. Mushrush, G. W.; Hazlett, R. N. Ind. Eng. Chem. Fundam. 1984,2 3 , 288. Powers, D. R.; Corcoran, W. H. Ind. Eng. Chem. Fundam. 1974, 13, 351. Pratt. G. L.; Rogers, D. J . Chem. SOC.Faraday Trans. 1 1979, 1089. Rebick, C. Ind. Eng. Chem. Fundam. 1981,2 0 , 55. Rebick, C. "Pyrolysis: Theory and Industrial Practice": Academic Press: New York, 1983; Chapter 4. Richardson, W. H.; O'Neal, H. E. "Comprehensive Chemical Kinetics"; Elsevier: Amsterdam, 1972; Vol. 5, Chapter 4. Sebasthn, H. M.; Simmick, J. J.; Lin, H. M.; Chao, K. C. J. Chem. Eng. Dafa 1980,25,68. Tilicheyev, M. D. Foreign Pet. Techno/. 1939, 7 , 209. Van Camp, C. E.; Van Damme, P. S.;Froment, G. F. Ind. Eng . Chem . Pro cess Des. Dev. 1984,2 3 , 155. Voge, H. H.; Good, G. M. J . A m . Chem. SOC. 1949, 7 1 , 593. Zaslonko, I. S.:Smirnov, V. N. Kinet. Katal. 1979,2 0 , 575.
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Received for review January 23, 1985 Revised manuscript received August 22, 1985 Accepted September 19, 1985
