these catalysts contained 19.8 and 5.4 weight % chlorine, respectively, they were inactive for isomerization a t our conditions. A probable explanation for their inactivity is that most of the h,ydroxyl groups in silica-aluminas are attached to silicon rather than aluminum atoms (Basila et al., 1964). Chlorination occurs, with the replacement of these hydroxyl groups leading to silicon-chlorine bonds, instead of aluminum-chlorine bonds obtained when alumina is chlorinated. Goble and Lawrence (1964) suggest that activity stems largely from the Lewis acid sites on the chlorinated aluminas which have extreme electronattracting capacity. Acknowledgment
We acknowledge the valuable assistance of M. R . Basila, F. E. Lutinski, and ’W.L. Kehl in the instrumental analyses and of K. I. Miller in the catalyst preparation. literature Cited
Basila, M. R., Gulf Research & Development Co., Pittsburgh, Pa., private communication, 1965. Basila, M. R., Kantner, T. R., Rhee, K . H., J . Phys. Chem. 68, No. 11, 31917 (1964).
Egloff, G., Hulla, G., Komarewsky, V. I., “Isomerization of Pure Hydrocarbons,” p. 28, Reinhold, Kew York, 1942. Evans, H. D., Fountain, E. B., Ross, W. E., Preprints 27th Midyear Meeting, API Division of Refining, San Francisco, 1962. Goble, A. G., Haresnape, J. N. (to British Petroleum Co.), Brit. Patent 953,187 (March 25, 1964). Goble, A. G., Haresnape, J. N. (to British Petroleum Co.), U. S. Patent 3,218,267 (Nov. 16, 1965). Goble, A. G., Lawrence, P. A., Preprints, Proceedings, Third International Congress on Catalysis, Amsterdam, 1964. MacIver, D. S., Tobin, H. H., Barth, R . T., Catalysis 2, 485 (1963). Massoth, F. E., Gulf Research & Development Co., Pittsburgh, Pa., private communication, 1967. O’May, T. C., Sixth World Petroleum Conference, Section 111, Paper 4, FrankfurtlMain, 1963. Ridgeway, J. A., Schoen, W., Preprints of Division of Petroleum Chemistry, 4, 2A, Boston, 1959. Riordan, M. D., Estes, J. H. (to Texaco), U. S. Patent 3,242,228 (March 22, 1966). Thomas, C. A., “Anhydrous Aluminum Chloride in Organic Chemistry,” p. 787, Reinhold, New York, 1941. RECEIVEDfor review May 9, 1969 ACCEPTED September 17, 1969
HYDROCRACKING OF n-HEXANE AND CYCLOHEXANE OVER ZEOLITES ALEXIS
VO O R H I E S ,
JR.,
A N D
Louisiana State University, Baton Rouge, La.
WI L L I A M
J.
HATCHER,
JR.’
70821
The lhydrocracking reaction, scission of carbon-to-carbon bonds plus hydrogenation, was investigated, using n-hexane and cyclohexane as reactants. Two crystalline aluminosilicate catalysts were studied: the hydrogen, or acid, form of synthetic faujasite and mordenite. Both catalysts were extremely active for hydrocracking. Integral reactor data were correlated using a conventional Langmuir-Hinshelwood model. The reaction rate constant was found to be a n Arrhenius function of temperature with activation energies comparable to catalysts with much larger pore diameters. The model was first-order with respect to the hydrocarbon, and the effect of increasing the hydrogen partial pressure was compatible with a “dual-site” mechanism. Typical reaction conditions were 500’ to 800’ F., 750 p.s.i.g., 10 moles of hydrogen per mole of hydrocarbon reactant, and liquid hourlly space velocities of 1 to 8.
THE,hydrocracking
of low-octane naphtha is a scheme being considered for producing liquefied petroleum gas (LPG) in areas lacking; natural gas. Commercial plants have been installed in some areas. Typical hydrocracking catalysts for this type of operation, and other feedstocks as well, have been composed of dispersed metals or metal
’ Present address, Chemical Engineering Department, University of Alabama, Tuscaloosa, Ala. 35486
sulfides on conventional supports such as silica-alumina. This paper describes the results of an investigation of two zeolite catalysts for hydrocracking: the hydrogen, or acid, form of synthetic faujasite and synthetic mordenite. Both catalysts were impregnated with palladium. Pure hydrocarbons, n-hexane and cyclohexane, were used as reactants, chosen since they represent some typical molecular structures found in naphtha. VOL. 8 N O . 4 DECEMBER 1969
361
Synthetic zeolites are unique materials in that they have an extremely regular, uniform crystalline structure consisting of three-dimensional networks of silicon, aluminum, and oxygen atoms. Synthetic faujasite is composed of clusters of interconnected porous “cages.” Windows, approximately 9 A. in diameter, offer access into the inner cavities. Mordenite, on the other hand, has parallel “micropores,” only 6 to 7 A. in diameter, that transverse the entire crystal. The mordenite structure is somewhat analogous to a tube bundle. Experimental System
The experimental equipment used for this research was constructed a t the Esso Research Laboratories, Baton Rouge, La. The unit consisted of a small fixed-bed reactor designed for once-through, down-flow continuous operation, a fluidized-bed sand bath to provide an isothermal system, feed metering systems, and product recovery. The liquid hydrocarbon feeds, n-hexane and cyclohexane, were Phillips pure grade, and were fed by a high precision Ruska pump. Dry electrolytic hydrogen was fed from a cylinder through a flowmeter. The off-gas rate was measured by a wet-test meter, and an F&M gas chromatograph was used to analyze the product gases. The Inconel reactor was 0.62 inch in diameter by 8 inches in length. An error analysis of this experimental system indicated that individual reaction rate constants measured by the system should have 95% confidence limits of about *lo%. The measurement responsible for most of this uncertainty was the catalyst temperature. The catalysts used were obtained from the Esso Research Laboratories. The synthetic faujasite was obtained originally from the Linde Co. as its SK-100 catalyst. The original mordenite crystals were obtained from the Norton Co. as 1- to 5-micron particles of sodium mordenite. After being exchanged to hydrogen-mordenite, impregnated with palladium, and pilled a t the Esso Research Laboratories, the catalyst was crushed to provide particles of approximately 0.6-mm. diameter. The faujasite catalyst pills were also crushed to this size. Both catalysts contained 0.5 weight CC palladium. Kinetic Model
The initial kinetic model for hydrocracking n-hexane was based on the reaction
[n-C62 1-Cg’s]+ H 2
k i
hydrocracked products
where all of the hexane isomers are considered together. The rate of hydrocracking could be expressed in a pseudohomogeneous form as
Rate = -dCA/dt = h C 4 C B
(1)
Since the hydrogen concentration is always large in comparison with the hydrocarbon concentration, in order to prevent catalyst activity loss due to “coking,” the hydrocarbon concentration could be considered rate-controlling. This yields the familiar first-order reaction expression
-ln(l - x) = htH
(2)
Shortly after beginning the experimental program it was realized that the simplified first-order expression would not fit the data adequately; therefore, a conventional Langmuir-Hinshelwood model was tried. The simplified 362
I & E C PRODUCT RESEARCH A N D DEVELOPMENT
rate constant would be related to Langmuir adsorption isotherms for a reaction rate-controlled system by
h = h o K ~ / ( +1 KAPA + K B P B+ Kpp,)”
(3)
Since the hydrogen partial pressure is always large, it might be assumed that K B>> ~Kapa ~ + K p p p .Then
h = hoKa/(l
+ KBpB)”
(4)
Since the data in this study were obtained with an integral reactor, partial pressures of the components were changing along the length of the catalyst bed. However, the hydrogen partial pressure was very large in all cases and remained almost constant. Therefore, all the terms in Equation 4 are essentially independent of conversion. The final form of the hexane hydrocracking model, then, is
- h ( I - x) = [h,KA/(1+ K B P B ) “ ]
tH
(5)
where
tH= [3600 W * p g * M ] / [ F+( lR ) ]
(6)
The model for hydrocracking cyclohexane can be developed in a similar fashion. The basic reaction is k
[ C H Z M C P ] + n H 2 i h y d r o c r a c k e d products The six-carbon-atom naphthenes are considered together, and m = 1 for the ring-opening reaction and m = 2 for the production of C1 to C5 paraffins. Then the rate of hydrocracking of naphthenes could be expressed as
Rate = -dCc/dt = hlCcCB”
(7)
Again, assuming the hydrocarbon concentration as ratecontrolling
-dCc/dt
zz
hiCc
(8)
and
-ln(l - x) = hitH
(9) Simplifying the Langmuir adsorption isotherm relationship in a similar manner to the hexane model yields
hi = hi oKc/ (1 + K B P B ) ” (10) Then the final form of the cyclohexane hydrocracking model is -h(l - x ) = [hlOKc/(l+ KBpB)”]tH
(11)
Effect of Contact Time
A series of runs was made for each reactant and each catalyst a t a constant temperature and total pressure and relatively constant partial pressures. The contact time was varied by varying hydrocarbon and hydrogen feed rates a t a relatively constant ratio of these two rates. The data from these studies strongly suggested the firstorder reaction rate with respect t o the hydrocarbon. For example, Figure 1 illustrates the data for hydrocracking hexane over the faujasite catalyst. As can be seen, the function -In (1 - x) appears to have a linear relationship with contact time. This relationship was found to be the case in hydrocracking hexane with the mordenite catalyst and hydrocracking cyclohexane with both zeolite catalysts. Dual Site vs. Single Site
The coefficient, n, on the adsorption terms in the model would be equal to 2 for a dual-site reaction mechanism
1.50
171-
The data were tested with the dual-site model by setting n = 2 and taking the square root of the reciprocal of Equation 4 in order to linearize. Then
1 .oo
-
0.75
w
0.50
k - ’ ‘ = (koKA ) - l L
+ (hoK,) ‘ K R P B (12)
For a single-site model, n = 1 and the reciprocal of Equation 4 yields
2 0
0.25
l / h = l/hoKA 0
20
40
60
80
100
120
CONTACT T I M E , SEC.
Figure 1 . Effect of contact time on conversion, hexane hydrocracking over faujasite 750’ F., 765 p.s.i.a.
and equal to 1 for a single-site mechanism. One “dualsite” mechanism for :hydrocracking would be a system wherein an adsorbed molecule reacts with another molecule on adjacently situated active centers. This may be described as follows:
A + l1ZAl1 B + l?=B1? A l l -k B1?+ Pli P11-+ P + 1 1 s12-+s
+ S1,
+12
Another dual-site mechanism could be a system wherein one of the reactants is adsorbed on one active site. One of the adjacent sites must be unoccupied for reaction to occur. During the reaction, part of the adsorbed molecule is connected to the original site and part to the site that was originally vacant. At the completion of the reaction, one of the hydrocarbon fragments is desorbed from one site and the other fragment from the second site. This might be described as:
A t. 1 l Z A l I
+ 1JZA1112 PI1 + S1s A1112 + B P+
All
+ (KB/koKA)PB
(13)
Equations 12 and 13 were tested with the data, and both had acceptable fits-for example, the data for hydrocracking hexane over the faujasite catalyst are shown in Figures 2 and 3. Equation 13 (Figure 3) yielded a negative reaction rate constant when fitted to the data. The negative reaction rate constant is, of course, unrealistic; therefore, the single-site mechanism is rejected. Similar comparisons of dual-site and single-site mechanisms were made also for hydrocracking cyclohexane with faujasite catalyst, hydrocracking n-hexane with the mordenite catalyst, and hydrocracking cyclohexane with the mordenite catalyst. I n each case the single-site equation yielded a negative reaction rate constant. Therefore, the dual-site model is accepted as more compatible with the data. Effect of Temperature
Data were taken over a range of temperatures for each hydrocarbon reactant and each catalyst. The effect of temperature on the true rate constants and hydrocarbon adsorption coefficients could not be separated. Therefore, the following relationships were used:
k ; = koKA
(14)
h;o = hioKc
(15)
and Arrhenius plots are shown in Figure 4 for the rate constants. The symbols represent the average value of all experimentally determined rate constants a t a given temperature. Each symbol represents the average of three to eight individually determined rate constants. The slopes indicated activation energies of 48 to 49 kcal. per gram
+
-s
P11 --+
s12
11
+12
A single-site mechanism involving two reactantshydrocracking, for example-would be a system wherein one of the reactants is adsorbed on the catalyst surface. Reaction occurs when the other reactant in the gas phase “collides” with the adsorbed reactant. The single-site system could be described with the hydrogen in the gas phase as follows:
0 10
0
20
30
40
50
H2 PARTIAL PRESSURE, ATM
Figure 2. Dual-site model, hexane hydrocracking over faujasite
A +lZAl A 1 t.B + SI + P s1 -3 s + 1 However, other parts of the model were developed on the assumption of hydrogen adsorption, and adsorbed hydrogen should react as well as gas-phase hydrogen. Therefore, it was not entirely surprising t h a t the dual-site mechanism was more compatible with the data.
0
10
20
30
40
50
Hp PARTIAL PRESSURE, ATM.
Figure 3. Single-site model, hexane hydrocracking over faujasite VOL. 8 N O . 4 DECEMBER 1 9 6 9
363
Table I. Hydrocracking of n-Hexane-Cyclohexane Mixtures
RelatzLe Acticitq n-Hexane ConLersion Cylohexane Conbersion Feedstock
104/i‘R
Catalqst
100Cr n-Cr
50Lc n-C OO‘, CH
100Lc CH
5OCcn-C6 5O‘, CH
Pd-H-faujasite Pd-H-mordenite
1 100
1 30
15 20
15 100
This equation used with Equation 12 permits solving for the reaction rate constant and the hydrogen adsorption coefficient. Similarly, data a t other temperatures on both catalysts were used to calculate hydrogen adsorption coefficients and reaction rate constants. Figure 5 is an Arrhenius plot of the hydrogen adsorption coefficient for the faujasite and mordenite catalysts.
illustrates these results, showing that cyclohexane is preferentially converted as compared to n-hexane, when the two hydrocarbons are mixed. This behavior of the mordenite catalyst can be explained on the basis of a competitive adsorption phenomenon. For reactions catalyzed by a solid surface, the reaction rate is not only a function of the reactivity of the reactants but also dependent on the surface area occupied by the reacting species. I n a reaction system involving mordenite, where both compounds are present, the naphthene is probably preferentially adsorbed and converted. In this manner, the apparent rate of hydrocracking of the two types is reversed. An example of the important effect of competitive adsorption has been reported for a similar catalytic system (Beecher et al., 1967). I t was found that the hydrocracking rate of n-decane is lowered considerably by the presence of decahydronaphthalene (Decalin) on mordenite catalysts. The faujasite catalyst also might preferentially adsorb cyclohexane; however, the results of hydrocracking the mixture would not illustrate this possibility. Cyclohexane is 15 times more reactive than n-hexane, and cyclohexane conversion would be very high compared to n-hexane conversion regardless of whether cyclohexane was preferentially adsorbed or whether the adsorptivities of cyclohexane and n-hexane were about equal.
Hydrocracking of Hexane-Cyclohexane Mixture
Relative Hydrocracking Activity
A series of experiments was made to investigate hydrocracking a 50/50 volume % ’ mixture of hexane and cyclohexane with both catalysts. As shown in Figure 4, the reactivity of cyclohexane was higher than n-hexane with the faujasite catalyst for the pure compound studies. The same ratio of reactivities was found in hydrocracking the mixture with faujasite, and the results of hydrocracking the mixture were predicted successfully from the results of the pure compound studies. With the mordenite catalyst, the reactivity of the hexane was higher than the cyclohexane in pure compound studies; the reverse was the case in hydrocracking the mixture. Table I
The hydrocracking activities of the zeolites tested were extremely high. A direct comparison of the hydrocracking activity of the mordenite and faujasite with both reactants indicated that mordenite was the more active. A comparison of the ability of the zeolites to hydrocrack n-hexane and literature data (Hartwig, 1964) on some metal oxides is shown in Table 11. The zeolites are much more active than any of the metal oxide catalysts.
Figure 4. Effect of temperature on reaction rate constants
mole for hydrocracking hexane over both faujasite and mordenite, and 31 to 32 kcal. per gram mole for hydrocracking cyclohexane over both zeolites. “Apparent” activation energies from the slopes of Arrhenius plots of the simplified rate constants were 54 to 55 kcal. per gram mole for hydrocracking a-hexane and 35 to 36 kcal. per gram mole for hydrocracking cyclohexane. These apparent activation energies compared well to literature data handled in the same manner (Hartwig, 1964; Iijima et al., 1963). As illustrated in Figure 2, the data obtained in hydrocracking n-hexane a t 750°F. with the faujasite catalyst can be represented by the following linear equation
h-’ ’ = 1.10+ 0.086 P B
(16)
Products from Hydrocracking
A close examination of the products from hydrocracking n-hexane and cyclohexane over the zeolites resulted in several interesting observations. One assumption in the basic model was that all of the hydrocarbon isomers could
MORDENITE
Table II. Relative Catalyst Activity in Hydrocracking of n-Hexane
FAUJASITE 2
-1.5
8.0
8.5
9.0 9.5 10 4 / r v
10.0
Figure 5. Effect of temperature on hydrogen adsorption coefficients 364
I & E C PRODUCT RESEARCH A N D DEVELOPMENT
Catalyst 0.55 Pd on
Relative Catalyst Activity
H-Mordenite H-Faujasite
8000 80 1 0.5 0.1
A1201
Ti02 Zr02
be treated as a single compound (Figure 6). The high isomerization activity has been reported on both catalysts (Beecher, 1967; Voorhies and Bryant, 1967), and Figure 6 reinforces the previous literature. It shows the hexane isomer concentration in the total hexane paraffin mixture us. hydrocracking conversion over the faujasite catalyst. The data indicate essentially an equilibrium mixture of the hexanes over the full range of hydrocracking conversion. The dashed lines in Figure 6 indicate equilibrium values of the hexane isomers (Ridgway and Schoen, 1959). The data indicate two possibilities: that the hexane isomers all hydrocrack a t about the same rate, thus maintaining the same relative concentrations independent of the amount of hydrocracking, or that if one or more of the hexane isomers hydrocrack preferentially, the isomerization rate is rapid enough to prevent that isomer or isomers from being depleted. I n any event, the assumption of handling all the hexane isomers as one compound appears to be justified, in that the ratio of hexane isomers remains constant as hydrocracking increases. Data from hydrocracking n-hexane over the mordenite catalyst and cyclohexane over both catal.ysts support the same conclusions. Another observation concerned the hydrocracked fragments. As observed on other catalysts (Henke and Schmid, 1967; Pollitzer et al., 1967), the higher carbon atom molecules were in higher concentration in the product than would be expected if a !simple cleavage of carbon-to-carbon bonds were the only reaction path. For example, in the simple reaction path n-hexane should split into two propane molecules, one et:hane and one butane, or one methane and one pentane. I n hydrocracking both n-hexane and cyclohexane ove:r the two zeolite catalysts, the methane-to-pentane and the ethane-to-butane molar ratios ranged between 0.1 and 0.7. This indicates that at least a portion of the products must originate from secondary reactions. Typical products are shown in Table 111. As compared to sim:ple carbon-carbon scission into pri-
m v
HYDROCRACKING, ‘i
Figure 6. Hexane isomer concentration in product hexanes, hexane hydrocracking over faujasite at 750” F.
mary products, at least two alternative paths are possible. One would involve the formation of a nine-carbon-atom or larger complex followed by hydrocracking of the complex to form predominantly butanes and pentanes. For example, a three-carbon-atom fragment (carbonium ion) may join with an adsorbed six-carbon-atom molecule (olefin) and produce a nine-carbon-atom complex (carbonium ion); then the complex wouid hydrocrack. A second path would be the alkylation of fragments consisting of one to three carbon atoms to form the “excess” butanes and pentanes. The first alternative is the more likely path. I t is consistent with carbonium ion reactions. Some investigators have actually found product hydrocarbon molecules containing more carbon atoms than the feed molecules. Acknowledgment
The research staff a t the Esso Research Laboratories in Baton Rouge, La., deserves gratitude for furnishing the necessary equipment, catalysts, and invaluable consultation.
Table 111. Typical Products from Hydrocracking of n-Hexane and Cyclohexane
Feedstock n-Hexane
n-Hexane
Cvclohexane
Cvclohexane
Catalvst Temperature, ’ F. Pressure, p.s.i.g. LHSV, v.Jv.Jhr. HI/hydrocarbon feed, molar ratio Product Methane Ethane Propane Isobutane (2-msethylpropane) n-Butane Isopentane (2-methylbutane) n-Pentane 2,2-Dimethylbutane 2,3-Dimethylbutane 2-Methylpentane 3-Methylpentane n-Hexane Cyclohexane Methylcycloperitane
Pd-H-faujm ite
Pd-H-mordenite
Pd-H-faujasite
Pd-H-mordenite
750.0 750.0 1.1
600.0 750.0 4.1
700.0 750.0 4.1
650.0 750.0 2.0
8.9
12.6
9.5
9.9
Moles per 100 Moles Feed 2.6 7.7 86.0 6.5 9.4 4.8 2.8 5.0 2.2 12.4 8.5 8.8
0.9 5.4 41.1 18.5 11.6 9.4 4.2 7.2 4.6 14.4 9.6 10.6
...
...
...
...
0.7 2.5 8.5 17.5 6.7 11.5 4.5 1.4 1.3 6.9 4.8 6.4 34.5 10.2
2.9 12.7 69.9 8.7 12.9 3.6 1.4 0.6 0.9 1.5 1.o 1.3 29.1 7.4
VOL. 8 NO. 4 DECEMBER 1969
365
Nomenclature
tH
sum of all hexane isomers hydrogen concentration of hexanes (n-Cs plus i-CG’s), moles/ unit volume concentration of hydrogen, molesiunit volume concentration of naphthenes (MCP + CH), moles/ unit volume flow rate of hydrocarbon reactant, weight/unit time simplified reaction rate constant for hydrocracking hexanes simplified reaction rate constant for hydrocracking naphthenes (MCP + CH) reaction rate constant for hydrocracking hexanes reaction rate constant for hydrocracking naphthenes product of reaction rate constant times adsorption coefficient for hexanes, koKA product of reaction rate constant times adsorption coefficient for naphthenes, kl.oKc dynamic adsorption coefficient for hexanes dynamic adsorption coefficient for hydrogen dynamic adsorption coefficient for naphthenes dynamic adsorption coefficient for hydrocracked products active site molecular weight of hydrocarbon reactant exponent: 1.0 for “single-site’’ mechanism, 2.0 for “dual-site’’ mechanism partial pressure of hydrocracked products partial pressure of hexanes partial pressure of hydrogen product molecules from hydrocracking molar ratio of hydrogen fed to hydrocarbon fed
= superficial contact time based on catalyst weight
T = temperature, degrees Rankine, unless- otherwise specified
W = catalyst weight in reactor 3c
= fraction converted by hydrocracking
ps =
molar density of reactor gases at reactor conditions
Literature Cited
Beecher, R. G., Ph.D. thesis, Louisiana State University, 1967. Beecher, R. G., Voorhies, A., Jr., Eberly, P. E., Jr., Vol. 12, p. B-5, Division of Petroleum Chemistry, 154th Meeting, ACS, Chicago, Ill., September 1967. Hartwig, M., Brennstof-Chem. 45, 234 (1964). Henke, A. M., Schmid, B. K., Chem. Engr. Progr. 63, 51 (1967). Iijima, K., Shimizu, S., Furukawa, T., Yoshida, N., Bull. Japan Petrol. Inst. 5 , 1 (1963). Pollitzer, E. L., Mitsche, R. T., Addison, G. E., Hamblin, R . J., Hydrocarbon Process. 46, 175 (1967). Ridgway, J. A. Jr., Schoen, W., Vol. 4, p. A-5, Division of Petroleum Chemistry, 135th Meeting, ACS, Boston, Mass., April 1959. Voorhies, A,, Jr., Bryant, P. A., 61st National Meeting, A.I.Ch.E., Houston, Tex., February 1967. RECEIVED for review May 8, 1969 ACCEPTED September 2, 1969 61st Annual Meeting A.I.Ch.E., Los Angeles, Calif., December 1-5, 1968. Research conducted in the Petroleum Processing Laboratories, Chemical Engineering Department, Louisiana State University. Research project sponsored by Esso Research and Engineering Co.
HEXANE ISOMERIZATION OVER A ZEOLITE CATALYST R I C H A R D
BEECHER’
A N D
ALEXIS
Louisiana State University, Baton Rouge, La.
V O O R H I E S ,
JR.
70803
search for gasoline octane improvement processes has led to a considerable amount of research effort, both industrial and academic, in the area of paraffin isomerization. Through this effort, several widely different isomerization processes have been developed. One of the early processes used an acid halide type of catalyst, either supported on a solid or complexed with a hydrocarbon (Cheney and Raymond, 1946). The next major isomerization catalyst system was the dual-function catalyst which consisted of a hydrogenation-dehydrogenation component (dispersed metal) on an amorphous solid support (cracking component) (Ciapetta and Hunter, 1953). I n the 1960’s, another catalyst system was reported, which consisted of a dispersed metal on a crystalline aluminosilicate support (Rabo et al., 1961; Rabo and Schomaker, 1964).
The present work is based almost entirely on synthetic mordenite, a unique member of the crystalline aluminosilicate family. Other investigators have reported data on paraffin isomerization over a mordenite catalyst when used as a conventional dual-function type catalyst-Le., with a dispersed metal (Voorhies and Bryant, 1967). However, there has been very little mention of the use of synthetic mordenite, without any hydrogenation-metal component, as an isomerization catalyst. The present work deals with such a catalyst-i.e., without the addition of a hydrogenating metal to give it dual functionality. The hexane system was used to study the isomerizing properties of synthetic mordenite, and a kinetic model of hexane isomerization was developed from the resulting data.
Present address, Esso Research Laboratories, Baton Rouge, La. 70821
The equipment was obtained from Esso Research Laboratories, Baton Rouge, La., and housed in the Petroleum
THE
366
I & E C PRODUCT RESEARCH A N D DEVELOPMENT
Experimental
