Guggenheim, E. A,, Proc. Roy. SOC.A 183,213-27 (1944b). Guggenheim, E. A., “Mixtures,” Chap. XI, Clarendon Press, London, 1952. Hellwig, L. R., Van Winkle, hl., Znd. Eng. Chem. 45, 624 (1953). Helpinstill, J. G., Van Winkle, M., Ind. Eng. Chem. Process
Pierrotti, G. J., Deal, C. H., Derr, E. L., Znd. Eng. Chem. 51 ( l ) ,
Hildebrand, J. H., Scott, R. L., “Solubility of Non-electrolytes,” 3rd ed. 133, Dover Publications, New York, 1950. Huggins, I%., Ann. N . Y . Acad. Sci. 43, art. 1, 1-32 (1942). International Critical Tables, McGraw-Hill, New York, 1928. Kojima, K., Ochi, K., Nakawaza, Y., Intern. Chem. Eng. 9 (2),
Rejdy R , C., Sherwood, T. K., “Properties of Gases and Liquids,” pp. 7-25, PvlcGraw-Hill, New York, 1958. Renon. H.. Prausnitz, J. hI., A.Z.Ch.E. J . 14 ( l ) ,135-44 (1968). Sinor, J. E’., Weber, J: H., J : Chem. Eng. Data 5,’244 (1960). Stockhardt, J. S., Hull, C. M., Znd. Eng. Chem. 23, 1438-40
Merquardt, D. W., Chem. Eng. Progr. 55 (6), 65-70 (1959). Marshall, N., J . Chem. SOC.89, 1350 (1906). Nagel, O., Sinn, R., Chem. Ing. Techn., 38 (lo), 265 (1966). Nagel, O., Sinn, R., Chem. Zng. Techn. 39 ( l l ) , 671-6, 275-82
Tyrer, D., J . Chem. SOC.,101, 1104 (1912). Uchida, S., “Chemical Engineer’s Handbook,” J. Perry, ed., Chap. 13, 4th ed., McGraw-Hill, New York, 1934. Jchida, S.,. Ogawa,’S., Yamagusti, M., J CIpan. Sci. Rev. Ser. Z.
Design Develop. 7, 213-20 (1968).
342 (1969).
(1967).
Neretnieks, I., Ind. Eng. Chem. Process Design Develop. 7, 335-9 (1968).
O’Connell, J. P., Prausnitz, J. M., IND. ENG.CHEM.FUNDAM. 3, 347 (1964).
O’g% R. V., Ph.D. dissertation, University of California, erkeley, Calif., 1965. Orye, R. V., Prausnitz, J. M., Znd. Eng. Chem. 57 ( 5 ) , 18 (1965). Othmer, D. F., Znd. Eng. Chem. 44, 1872 (1952). Othmer, D. F., Chudgar, M. M., Levy, S. L., Znd. Eng. Chem.
44, 1872-8 (1952). Perry, J., ed., “Chemical Engineer’s Handbook,” 4th ed., Chap. 13, New York, 1963.
95-102 (1959).
Prausnitz, J. R.I., Eckert, C. A., Orye, R. V., O’Connell, J. P., “Com uter Calculations for Multicomponent Vapor-Liquid Equiligria,” Chap. 1-6, Prentice-Hall, Englewood Cliffs, N. J., 1m
7
’
(1931).
Eng.’Sci,’ 1,No. 2, 41 (1950):
’
.
Wilson, A., Simons, E. L., Znd. Eng. Chem. 44,2214 (1952). Wilson. G. Pvl.. J . Amer. Chem. SOC.84. 127-33 (1964a). Wilson: G. M.; J . Amer. Chem. SOC.84; 133-7 (1964b).’ Wilson, G. >I., Ileal, C. H., IND.ENG.CHEWFUNDAM. 1, 20-3 (1962).
Wohl, K., Trans. Amer. Inst. Chem. Engrs. 42, 215 (1946). RECEIVED for review December 23, 1968 ACCEPTEDMay 1, 1970 Work supported by the L. E. B. Foundation, Wageningen.
Thermal Reaction of Propylene Kinetics Taiseki Kunugi, Tomoya Sakai, Kazuhiko Soma, and Yaichi Sasaki Department of Synthetic Chemistry, Faculty of Engineering, University of Tokyo, Hongo, Tokyo, J a p a n
Kinetics of the thermal reaction of propylene was studied at temperatures ranging from 703’ to 854’C., atmospheric pressure, and residence times from 0.078 to 3.3 seconds with and without nitrogen dilution. Main primary products were ethylene, methane, hydrogen, butenes, and butadiene in the approximate ratio of 5 : 3 : 1 : 1 : 1 at initial stages of the reaction. Other primary products were methylcyclopqntene, hexadienes, acetylene, and ethane. Secondary products were cyclopentadiene, benzene, polycyclic aromatics, cyclopentene, and toluene. Selectivities of formation of these products, except acetylene and ethane, showed little dependence on temperature. At higher partial pressure of propylene, the selectivities of ethylene and methane formation decreased to some extent. The effect of partial pressure of propylene on the rate of propylene disappearance leads to a three-halves-order equation. The rate constant is given as
k = 10’5*06
of propylene has been studied extensively (Amano and Uchiyama, 1963; Kallend et aZ., 1967; Laidler and Wojciechowski, 1960; Sakakibara, 1964; Wheeler and Wood, 1930). A few experiments at temperatures from 700’ to 850’ and atmospheric pressure cover the conditions of the industrial manufacture of olefins and aromatics by cracking hydrocarbon feedstocks. Analyses of the products have been limited to lighter hydrocarbons below CCor the products formed in narrow ranges of temperatures and conversions. Lack of clear discrimination between the primary and secondary products is due t o these limited analyses of the products. T H E R M A L REACTION
3 14
Ind. Eng. Chem. Fundam., Vol. 9,
No. 3, 1970
cc>/z/(mote’/z sec.).
Reaction products were analyzed in detail to differentiate the primary from the secondary products. The kinetics of the thermal reaction of propylene was discussed in comparison with that of ethylene. I n a following paper mechanisms of the reaction and of formation of higher hydrocarbons above CS are to be discussed. Experimental
Feed propylene was 99.35 mole % pure by gas chromatographic analysis, used without further purification. The impurity was propane, 0.65 mole yo.Oxygen content was less than 1 p.p.m. by weight. Commercially available nitrogen
H
40
1
Q)
8
t B
1
' I
8s
l
5
I
.k',
i I
I
I
I
I
10
20
30
40
(mol %)
Convereion of C3H6 Figure 2.
50
Selectivities of formation of butenes Symbols as in Figure 1
I
I
OO
1
I
1
I
IO 20 30 40 Conversion of GH6 (mol % )
1
1 50
Figure 1 . Selectivities of formation of ethylene, methane, and hydrogen
o
0
a
7 0 3 ~ .
A A
i
7 5 3 ~ .
0
W
4
804OC.
V
V
f
854'C.
(99.95 mole yo)was used as diluent after removal of trace oxygen over reduced copper net at 350' to 400'. The apparatus and the analytical techniques were essentially the same as those used for the studies of the thermal reaction of ethylene (Kunugi et al., 1969). I
Results and Discussion
The main products were ethylene, methane, hydrogen, butenes, and butadiene in the approximate ratio of 5 :3 : 1: 1: 1 a t initial stages of the reaction. Butenes were mostly 1-butene. Isobutylene (2-methylpropene) and trans- and cis-2-butene were also identified. The minor products were cyclopentadiene, methylcyclopentene, hexadienes, cyclopentene, benzene, toluene, ethane, acetylene, and polycyclic aromatic hydrocarbons (mainly naphthalene). Trace amounts of allene, methylacetylene, propane, cyclohexane, cyclohexadiene, 4-methylcyclohexene, xylenes, and styrene were also identified. The amount of carbon deposit on the reactor wall was very small and was generally neglected. Selectivities of the main products and the minor ones are plotted in Figures 1 to 8. The selectivity of polycyclic aromatics was calculated as mole per cent naphthalene equivalent, because most of these aromatics were identified as naphthalene by gas chromatographic analysis. As shown in the figures, selectivities of the products, except for acetylene (Figure 8, center) and ethane (Figure 8,
I
I
I
1
-
10 20 30 40 Conversion of C3He (mol % )
Figure 3.
0
Selectivity of formation of butadiene Symbols as in Figure 1
lower), are nearly independent of temperature in the range from 703' to 854OC. and conversions from 2.3 to 43 mole 70. Facts obtained are generally in line with those of Kallend et al. (1967) and Hurd and Meinert (1930). Temperature independence of selectivities of products except for acetylenp and ethane is discussed in the succeeding paper. Figures 1 t o 8 seemingly permit the conclusion that the primary products are ethylene, methane, hydrogen, butenes, 1,3-butadiene, methylcyclopentene, hexadienes, acetylene, and ethane, and the secondary products are cyclopentadiene, benzene, cyclopentene, polycyclic aromatics, and toluene. Decrease in selectivities of butenes (Figure 2) and butadiene (Figure 3) with conversion of propylene may be attributed to decomposition to form hydrogen, methane, ethylene (Figure l ) , acetylene (Figure 8, center), and ethane (Figure 8, lower), and polymerization t o form cycloolefins (Figures 4 and 5 ) Ind. Eng. Chem. Fundam., Vol. 9, No. 3, 1 9 7 0
3 15
I
\
/
I
A
,
I
I
I
I
I
I
I
IO
50
20 30 40 Conversion of C3Hs (mol 96)
(mol 96)
Converslon of C3H, Figure 4.
Figure 7. Selectivities of formation of polycyclics
Selectivity of formation of methylcyclopentane
Naphthalene equivalent, mole
%.
Symbols as in Figure 1
Symbols as in Figure 1
Jpv
Cyclopentadiene
v
(mol 96)
Conversion of C3He
L
\ Cyclopentene
V, I
I
I
1
I
I
I
30 40 20 IO Conversion of C3Hs (mol %)
I
50
Figure 5. Selectivities of formation of cyclopentene and cyclopentadiene
mverslon of %He
(mol 96)
Symbols as in Figure 1 I
I
I
I
I
IO
I
I
I
I
20
30
40
Converslon of C3H6 Figure 8. Upper.
v -. I
I
IO
20
Convtrslon of Figure 6. dienes
I
I
I
40
C3H6
(mol %)
I
I 50
Selectivities of formation of benzene and hexaSymbols as in Figure 1
316
I
30
Ind. Eng. Chem. Fundam., Vol. 9, No. 3, 1970
I
1
50
(mol 96)
Selectivities of formation of products
Toluene. Center. Acetylene. lower. Figure 1
Ethane.
Symbols as in
and hexadienes (Figure 6). Characteristic changes in selectivities of cycloolefins and hexadienes with conversion, in connection with those of benzene (Figure 6), toluene (Figure 8, upper), and polycyclics (Figure 7 ) , indicate that the latter are formed through the demethylation and/or dehydrogenation of the former. Formations of five-membered cycloolefins may be attributed to allyl-type radicals (Bryce and Ruzicka, 1960; Kunugi et al., 1969), as discussed in the following paper.
6o
m -.-•
'.'
-0
0
50-
C2H4
?i!
1
.
(D
In 0 40 B
I .o
0.5
ti
I
I
i 1.00
OO
0.50 Partlal weawe of %He
0 30 \
"
i-I
s
H2
A
-A 20.
I
1
-A\A I
I
I
I
,
I I
I
Figure 11. Effect of partial pressure of propylene on over-all rate constants of propylene disappearance
A kl = W
First-order 1 - In f 1 - x
, sec.-1
~
Three-halves-order
-
I .00
0.50
0
(atrn)
__
, sec.-1
atm.-l'z
Pmtial pressve of CjHs (atm) Figure 9. Effect of partial pressure of propylene on product distribution Ethylene
W
Methane
A
t. Residence time, sec. pCaH80 Partial pressure of propylene, atm. conversion of propylene, mole 7 0 X.
I
5
I
/.
-*-
Second-order
Hydrogen
U
,"0
0
9-.
I
I
v 030
[
l i / 6 !i / I
0.20
\
c 0
5
m u
$2
5
'
-
A
I
-
0.10
! B
Partlal pressure of C3Hs (atm)
Figure 1 2. equation
703'
I
0
Figure 10. Effect of partial pressure of propylene on product distribution
7530
3.0
2.0 Resldmw time (sec)
Conversion of propylene as three-halves-order x.
Conversion of propylene, mole
%
Upper
A V 0
Butadiene Butenes Cyclopentadiene Cyclopentene Methylcyclopentene
lower
0
A
7
Benzene Polycyclic aromatics (naphthalene equivalent, mole percent) Hexadienes Toluene
The main products in the pyrolysis of 1-butene were reported to be methane and propylene at 640" t o 760" and atmospheric pressure (Kunugi et cil., 1967). Distributions of butene isomers in thermal reaction of propylene are listed below a t 753' and conversion levels from 5 to 40 mole yo. At 753' the distribution of butenes is independent of conversion of propylene. This coincides with the tendency reported by Kallend et al. (1967). Ind. Eng. Chern. Fundam., Vol.
9, No. 3, 1970 317
Table 1.
Selectivities of Products in Thermal Reactions of Ethylene. and Propylene
Feed Olefin Conversion of olefins, mole yo Selectivity, mole
Butadiene Butenes Cyclopentene Cyclopentadiene a Kunugi et al. (1969).
5
5
35
A
B
AIB
C
D
C/D
(A/B)/(c/D)
20 2.3 1.2 2.3
3.9 0.5 0.2 0.9
5.1 4.6 6.0 2.6
9.8
5.3 4.0 0.6 3.7
1.8
2.8
2.5 2,3 1.1
2.6 2.4
%
Conversion of Propylene, Mole
1-Butene Isobutylene trans-2-Butene cis-2-Butene
Propylene
Ethylene
15
27
40
Av.
1.00 0.46 ... ...
1.00 0.39 0.47 0.39
1.00 0.45 0.42 0.41
1.00 0.46 0.41 0.33
1.00 0.43 0.43 0.38
Ind. Eng. Chem. Fundam., Vol. 9, No. 3, 1970
9.8 1.4 4.2
1.8
70
5.0
Selectivity of ethylene (Figure 1) shows little dependence of temperature and conversion of propylene. Kunugi et al. (1969) reported the thermal reaction of ethylene in the same ranges of temperatures and conversions as those in this paper. Ethylene was shown to be rather reactive-Le., the ratios of rates of pyrolysis of ethylene to propylene are 0.53, 0.37, 0.27, and 0.20 a t 703O, 753", 804O, and 854O, respectively. The experimental results shown in Figure 1 may be attributed to the inhibition effect of propylene, which reduces the rates of radical reaction. This may be verified by comparing the changes in selectivities of the products of thermal reactions of ethylene and propylene against conversions. Selectivities of butenes and butadiene, as the primary products, and cyclopentene and cyclopentadiene, as the secondary products, are listed in Table I a t conversions of 5 and 35 mole % of feed olefins and a t 804". These products are present in the thermal reactions of both ethylene and propylene. The ratios of their selectivities a t a conversion of 5 mole % to those a t 35 mole yo are also listed, A / B for ethylene and C / D for propylene, respectively. A / B is about two or three times as large as C / D . This indicates that the products in pyrolysis of ethylene are consumed about two or three times faster than in pyrolysis of propylene-i.e., ethylene is stable compared Eith propylene. The effect of partial pressure of propylene on product selectivities was studied by setting the propylene-nitrogen mole ratio as 1 to 3, 1 to 1, and 3 to 1, a t a temperature of 804' and residence times of 0.25 to 0.29 second. Results are shown in Figures 9 and 10. Selectivities of ethylene and methane decrease a t higher partial pressure of propylene and those of hydrogen and butenes decrease slightly. Those of toluene and polycyclics increase at higher partial pressure of propylene. Other products such as butadiene, cyclopentadiene, cyclopentene, methylcyclopentene, benzene, and hexadienes do not show notable dependence on partial pressure of propylene. These facts form a striking contrast t o those observed in the pyrolysis of ethylene (Kunugi et al., 1969). Rate constants of propylene disappearance calculated as first-, three-halves-, and second-order equations are plotted in Figure 11 against the partial pressure of propylene a t 804" and residence times of 0.25 to 0.29 second. The order is shown t o be approximately three-halves. Laidler and Wojciechowski (1960) and Kallend et al. (1967) reported the orders as three-halves and seven-fifths, respectively. I n this paper three-halves order is preferred and rate constants are calcu318
35
20 -
x 0
0
1.0
-
\ 01
I
I
I .oo
0.90 1000/T("K)
Figure 13.
Arrhenius plot
lated as shown in Figure 12. These lines do not cross the zero point of the abscissa a t any temperature. This seems to show the existence of an induction period, as stated by Kallend et al. (1967) and Amano and Uchiyama (1963). These periods calculated from Figure 12 are 0.46, 0.20, 0.055, and 0.016 sec. a t 703O, 753O, 804O, and 854O, respectively, shorter than those observed in pyrolysis of ethylene a t the same temperatures (Kunugi et ai., 1969). An Arrhenius plot (Figure 13) gives the rate constant for the steady state after the induction periods as
literature Cited
Amano, A,, Uchiyama, lX.,J . Phys. Chem. 67, 1242 (1963). Bryce, W. A., Ruzicka, D. J., Can. J . Chcm. 38, 835 (1960). Hurd. C. D.. bleinert, R. N., J . Amer. Chem. SOC.5 2 , 4978 (1930).
'
Kallend. A. S..Purnell. J. H.. Shurlock. B. C., Proc. Rov. SOC., Ser. A 300, 120 (1967).
Kunugi, T., Sakai, T., Soma, K., Sasaki, Y., IND.ENG.CHEM. FUNDAM. 8, 374 (1969). Kunugi, T., Tominaga, H., Abiko, S., Uehara, K., Ohno, T., Kogyo Kagaku Zasshi 70, 1447 (1967). Laidler, K. J., Wojciechowski, B. W., Proc. Roy. SOC.,Ser. A 259, 257 (1960).
Sakakibara, Y.,Bull. Chem. Soc. Japan 37, 1262 (1964). Sznarc, M., J . Chem. Phys. 17, 284 (1949). Wheeler, R. V., Wood, W. L., J . Chem. SOC.1930, 1819. RECEIVED for review December 12, 1968 ACCEPTED April 16, 1970
