Competitive catalytic hydrogenation in unsaturated hydrocarbon systems with sterically hindered double bonds

Article abstract of DOI:10.1135/cccc19981915

A competitive hydrogenation of unsaturated hydrocarbons (α-methylstyrene, cyclohexene, 1-methyl-cyclohex-1-ene, 1-tert-butylcyclohex-1-ene and 3-terr-butylcyclohex-1-ene) in binary and ternary systems with palladium-, platinum- and rhodium-supported catal

Full text of DOI:10.1135/cccc19981915

Competitive Catalytic Hydrogenation
1915
COMPETITIVE CATALYTIC HYDROGENATION IN UNSATURATED
HYDROCARBON SYSTEMS WITH STERICALLY HINDERED DOUBLE
BONDS
a1
b
a2
Petr KACER , Leiv LAATE and Libor CERVENY
a Department of Organic Technology, Prague Institute of Chemical Technology, 166 28 Prague 6,
Czech Republic; e-mail: 1 kacerp@vscht.cz, 2 cervenyl@vscht.cz
b Department of Industrial Chemistry, Norwegian University of Science and Technology,
Trondheim N-7034, Norway; e-mail: leivl@kjemi.unit.no
Received June 1, 1998
Accepted July 20, 1998
A competitive hydrogenation of unsaturated hydrocarbons (α-methylstyrene, cyclohexene, 1-methyl-
cyclohex-1-ene, 1-tert-butylcyclohex-1-ene and 3-tert-butylcyclohex-1-ene) in binary and ternary sys-
tems with palladium-, platinum- and rhodium-supported catalysts in a semibatch isothermal reactor at
20 °C under atmospheric pressure was studied. It was found that considerable variance in selectivity
values of competitive hydrogenation in a series of substrates with increasing substituent bulkiness is
caused by differences in adsorption and in reactivity of adsorbed molecules. In the case of ternary
systems, a change in selectivity of competitive hydrogenation of two substrates was observed, due to
the presence of a third substance, caused by a competitive adsorption of all three substrates and their
interaction on a catalytic surface.
Key words: Competitive hydrogenation; Palladium; Platinum; Rhodium; Adsorptivity; Heteroge-
neous catalysis; Unsaturated hydrocarbons.
Research on selectivity of catalytic hydrogenations still ranks among contemporary
tasks of heterogeneous catalysis1–3. The obtained data gather a valuable piece of knowl-
edge significant not only for the general theory of hydrogenation reactions but also for
the industrial application. Although there exists an immense amount of literature con-
cerning selective hydrogenations of alkene substrates, only an insignificant percentage
of the studies utilize the method of competitive hydrogenation reaction3–8. This work
involves determination of hydrogenation selectivities in systems formed by combina-
tion of substrates with substituents of a varied bulkiness (H, CH3, C(CH3)3) close to the
reaction center – double bond in a six-membered cyclic skeleton and in an alkene
model. Using the initial reaction rate values acquired in the hydrogenations of individ-
ual substances, relative adsorption coefficients of individual substrates were determined
from selectivity values of competitive hydrogenations. All these quantitative data
allowed a discussion relating to the effect of a bulky substituent in a close vicinity to a
double bond, with regard to formation of an adsorbed complex and to the surface reac-
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

1916
Kacer, Laate, Cerveny:
tion rate. The obtained results also enabled discussion about structural effects in hete-
rogeneous catalysis9–11 with regard to the effects of a varied active component of a
catalyst supported on an inert carrier.
EXPERIMENTAL
Chemicals
The substrates used were of commercial origin: α-methylstyrene (Slovnaft), cyclohexene (Koch-
Light), 1-methylcyclohex-1-ene (Aldrich), 1-tert-butylcyclohex-1-ene, 3-tert-butylcyclohex-1-ene
(Aroma) and were distilled before use. The solvent was methanol of analytical grade (Penta). Elec-
trolytic hydrogen 4.0 (Linde Technoplyn) was used.
Catalysts
The catalysts used Pt/C-Secomet AN (Doducco Kat. GmbH), Pd/C-Cherox 4100ch (Chemopetrol
Ltd.), Rh/C (DOT, ICT Prague) were characterized by the particle crystallite size, surface area and
active component surface area (Table I). The particle crystallite size was determined using on XRD
Seifert 3000P with CoKα and graphitic monochromator. The particle size was computed using an
one-point method, always from the most intense line of the monitored material. Since it exhibited
only a slightly elevated background on diffraction pattern, rhodium catalyst was X-ray-amorphous.
Platinum and palladium catalysts show a definite crystallite structure. A measurement of physical
adsorption of nitrogen was carried out using a Pulse Chemisorb 2700 system, Micromeritics; the total
surface area (SBET) was evaluated from the BET region. The surfaces of catalysts supported on acti-
vated carbon were subject to error, caused by the instrumentation used which, due to their great ex-
tents, did not enable an exact determination. The error reached approximately up to 10% of the
determined value. Specific surface of the catalyst active component was determined using the method
of selective hydrogen chemisorption and successive titration of its oxygen-adsorbed quantity with
potentiometric indication of the equivalence point.
Apparatus and Kinetic Measurements
Kinetic measurements were carried out in a semibatch stirred reactor at 25 °C under hydrogen press-
ure of 101.3 kPa in methanol. A detailed description of the equipment is given elsewhere12. All the
measurements were carried out in the kinetic region. The reaction course was monitored by measuring
TABLE I
Characteristics of hydrogenation catalysts
Catalyst
Grain size, mm
Particle size, nm
SBET, m2 g−m1et
SMET, m2 g−m1et
a
3% Pd/C
5% Pt/C
5% Rh/C
<0.02
<0.05
<0.02
20.2
15.5
<5.0
1 161
778
45.3
75.3
1 201
a Not determined.
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

Competitive Catalytic Hydrogenation
1917
the time dependence of hydrogen consumption and time changes of molar concentrations obtained by
chromatographic analysis (GLC). In hydrogenations, 2 mmol of substrate was used, 1 mmol of each
substrate in competitive hydrogenations in 15 ml of methanol. The catalyst amount ranged between
0.1–0.01 g, depending on the substrate and catalyst type used.
In binary systems, which did not consist of 1-tert-butylcyclohex-1-ene substrate, competitive hy-
drogenations were carried out using 1 mmol of each substrate. In the case that one of the substrates
was 1-tert-butylcyclohex-1-ene, it was necessary to use alkene/1-tert-butylcyclohex-1-ene molar ratio
1 : 20 because of very low concentration changes of this substance in the course of competitive hy-
drogenation. Similarly, the problem of low contents of tert-butylcyclohexane in the course of compe-
titive hydrogenation in ternary systems was solved.
Analytical Method
Samples withdrawn at appropriately selected time intervals were analyzed using a gas chromatograph
HP 5890 Series II plus (Hewlett–Packard) with flame-ionization detector (FID) and capillary column
HP-20M (length 50 m, inner diameter 0.32 mm, thickness of stationary phase 0.32 µm) at tempera-
ture programs between 333–453 K and overpressure of carrier gas (N2) 80 kPa. The substance con-
tents in the reaction mixture were determined using the internal standard method. The internal
standard was n-decane (Aldrich).
RESULTS AND DISCUSSION
For the purpose of this work, the above-mentioned alkenes can be divided into two
groups, the first being made up of substances containing in their molecule a six-carbon
cyclic skeleton containing a double bond and bearing substituents of a varying bulki-
ness (cyclohexene, 1-methylcyclohex-1-ene, 1-tert-butylcyclohex-1-ene). The second
group consists of two comparative model substances containing a disubstituted double
bond. In the case of 3-tert-butylcyclohex-1-ene, the equal six-carbon skeleton is in-
volved, which contains a bulky tert-butyl substituent in α-position to the double bond;
in the case of α-methylstyrene, the terminal double bond bears an aromatic ring conju-
gated with the investigated reaction center. All substances did not significantly vary in
their molecular weights (82.15–138.25 g mol–1), the influence of which is hence as-
sumed insignificant, relative to their adsorption terms discussed through the relative
adsorptivities.
Hydrogenation of Individual Substrates
Hydrogenations of individual alkene model substances were performed, excluding
3-tert-butylcyclohex-1-ene, which was available only in a mixture with 1-tert-butyl-
cyclohex-1-ene. The obtained time dependencies of hydrogenated substrate concentra-
tions were utilized to determine initial reaction rate values, which were read from the
linear region of the dependence c = f(t). These values were subsequently used for cal-
culation of relative adsorption coefficients. Even at high conversions (>90%), the reac-
tions were mostly of zeroth order with respect to substrate concentration. All
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

1918
Kacer, Laate, Cerveny:
hydrogenations were accomplished with total conversion of the starting substances,
having nature of a simple reaction, characterized by the scheme A → B. In the case of
substituted cyclohexenes on palladium and rhodium catalysts, no presence of positional
isomers, resulting from the double bond migration, was detected by chromatography. A
summary of the initial reaction rates for hydrogenations of individual model substances
is provided in Table II.
From Table II it is apparent that the values of initial reaction rates of selected alkene
substrates exhibit considerably dissimilar figures, whose trend, in regard to a substrate
type, is in all the selected catalysts identical and decreases in the series: α-methyl-
styrene > cyclohexene > 1-methylcyclohex-1-ene > 1-tert-butylcyclohex-1-ene. From
the values of initial reaction rates of individual alkenes, it is also possible to set up the
following sequence of the selected catalysts in the order of decreasing activity in the
double bond hydrogenation: Pd/C > Rh/C > Pt/C.
From the provided results of hydrogenation of individual substrates it follows that
the assumption of an equal mechanism of the catalytic reaction with all model sub-
stances was fulfilled. Furthermore, all the three catalysts selected for quantitative as-
sessment of the bulky-substituent effect upon the course of a heterogeneous catalytic
reaction conducted a constant-like factor manner and changes in reactivity and adsorp-
tivity incurred only due to the structure of hydrogenated substances.
TABLE II
Initial hydrogenation rates of substrates
−1
cat
Catalyst
Pd/C
Substrate
r0, mmol min–1
g
α-methylstyrene
14.4 ± 0.2
26.0 ± 2.0
3.3 ± 0.1
cyclohexene
1-methylcyclohex-1-ene
1-tert-butylcyclohex-1-ene
0.72 ± 0.02
Pt/C
α-methylstyrene
2.1 ± 0.1
19.0 ± 1.0
1.5 ± 0.1
0.13 ± 0.02
cyclohexene
1-methylcyclohex-1-ene
1-tert-butylcyclohex-1-ene
Rh/C
α-methylstyrene
7.2 ± 0.2
24.0 ± 1.0
1.9 ± 0.1
0.22 ± 0.01
cyclohexene
1-methylcyclohex-1-ene
1-tert-butylcyclohex-1-ene
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

Competitive Catalytic Hydrogenation
1919
Competitive Hydrogenations in Binary Systems
A relatively simple relation for selectivity, defined using the reactivity ratio of both
substances, can be established if the kinetics of these substances involved in a compe-
titive reaction can be expressed with an equation of the same form. If the rate-determin-
ing step is a surface reaction and the reaction is carried out far from equilibrium, in the
simplest case with an assumption of ideal behaviour, it is possible to write for the
hydrogenation of A and B substrates:
kAHKAcA
dcA
V
dt w
rA =
= −
(1)
(2)
1 + K c + K c + K c + K c
∑
A A
B B
H H
i i
kBHKBcB
dcB
V
rB =
= −
.
dt w
1 + K c + K c + K c + K c
i i
∑
B B
A A
H H
The hydrogen concentration and its adsorption constant are included in the kinetic con-
stant kAH. From Eqs (1) and (2), it is possible to derive a relation for the selectivity of
competitive hydrogenation commonly known under the name Rader–Smith equation
[18]:
log (cA/cA0) kAH
K
=
A = SAB
.
(3)
log (cB/cB0) kBHKB
In ideal case, the dependence log (cA/cA0) on log (cB/cB0) is a straight line charac-
terized by the slope SAB. The measured data very well fulfilled the linear characteristic
of this equation, which is apparent from the values of correlation coefficients (f) which
ranged in an interval (0.91–1.00). Table III shows the SAB selectivity values obtained
using this procedure. Relative adsorption coefficients KA/KB, shown also in Table III,
were computed using the acquired SAB values and initial reaction rates r0 of hydrogena-
tion of individual substrate, which were in the above Eq. (3) substituted for reaction
rate constants kAH and kBH
.
The values SAB, rA0/rB0, KA/KB acquired from competitive hydrogenations of binary
systems of model substrates fostered a discussion about the structural effect upon reac-
tivity and adsorptivity of substituted alkenes. In a series of structurally similar sub-
strates, two extreme cases of substituent effect upon the course of a heterogeneous
catalytic reaction may arise. In the first case, substrates exhibit the same reactivity in
the adsorbed state; however, they differ significantly in their adsorptivity. The second
case includes substrates with an equal adsorptivity, differing, however, in the reactivity
of molecules in the adsorbed state. It is apparent from Table III that a combination of
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Kacer, Laate, Cerveny:
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

Competitive Catalytic Hydrogenation
1921
both above-mentioned extreme cases is involved with the selected catalysts, where it
depended upon what particular substrate effect of the two predominated.
It is also apparent from Table III that selectivity values of competitive hydrogena-
tions in binary systems α-methylstyrene (substrate A)–cyclohexene with a varying
bulky substituent bonded on the double bond (substrate B) are always shifted in favor
of a substrate with di-substituted terminal double bonds, which is in conformity with
the generally known principles9,10. The only exception was the system α-methyl-
styrene–cyclohexene on rhodium catalyst, where the selectivity was shifted in the as-
sumed direction only very inexpressively, which was primarily due to a different
reactivity of these substances. Selectivity of competitive hydrogenation in these binary
systems increases with growing bulkiness of the substituent hindering the double bond
in the series H < CH3 < C(CH3)3 always by one order of magnitude. This phenomenon
is caused on the platinum catalyst by a higher adsorptivity of α-methylstyrene due to
the terminal double bond; on palladium, there is a less significant difference between
reactivity and adsorptivity effects. It is impossible to conclude similarly for the rho-
dium catalyst though, since the adsorptivity effect again prevailed in the case of cyclo-
hexene and 1-methylcyclohex-1-ene, whereas in the case of 1-tert-butylcyclohex-1-ene
the case was just opposite.
The obtained values of discussed quantities in systems of substrates containing the
same skeleton, cyclohexene ring, were interesting. In this case, even the potential in-
fluence of the rest of α-methylstyrene molecule was no longer present, location of the
double bond, and the substituent on the reaction center remaining the sole variables. In
competitive hydrogenation in cyclohexene–1-methylcyclohex-1-ene and cyclohexene–
1-tert-butylcyclohex-1-ene, there was again an order-of-magnitude in selectivity values
depending on the substituent bulkiness. In all these binary systems on all the selected
catalysts, a highly increasing negative influence upon the surface reaction rate with
increasing substituent bulkiness was evident, whereas the adsorbed complex formation
had only a trifling effect, which is evident from a minimum sensitivity of relative ad-
sorption coefficients to the substituent size. From the acquired data, it follows that
adsorptivity is affected mainly by the cyclohexene skeleton and the bulky substituents
do not play a significant role, which is very markedly displayed in the case of rhodium
catalyst. All these conclusions were confirmed by competitive hydrogenations of the
1-methylcyclohex-1-ene–1-tert-butylcyclohex-1-ene binary systems. Again, the reac-
tivity effect here predominated over the effect of adsorptivity. The palladium catalyst
was an exception: the influence of both of the mentioned factors was approximately the
same; however, the value of relative adsorptivity was relatively low. The difference in
selectivities of competitive hydrogenations of the 1-methylcyclohex-1-ene–1-tert-
butylcyclohex-1-ene binary system, related to the individual catalysts, was insignificant
in comparison with all the above discussed binary systems.
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

1922
Kacer, Laate, Cerveny:
Selectivity values in the 1-tert-butylcyclohex-1-ene–3-tert-butylcyclohex-1-ene sys-
tem were determined as well. Since the cyclohexene molecular skeleton was again in-
volved, the position of the bulky substituent was the sole variable factor. Selectivities
of competitive hydrogenations on all the selected catalysts show values one order of
magnitude different from the cyclohexene–1-tert-butylcyclohex-1-ene system and
equal, in the case of palladium and rhodium catalyst, or similar, in the case of platinum
catalyst to those for the 1-methylcyclohex-1-ene–1-tert-butylcyclohex-1-ene system.
Since the 3-tert-butylcyclohex-1-ene substrate was not available in required purity, it
was not possible to determine the values of relative reactivity and relative adsorptivity.
Nevertheless, it is possible to claim that the effect of tert-butyl group in the α-position
to the double bond of cyclohexene has approximately the same influence as the methyl
group bonded directly to the reaction center.
The feasibility of an indirect determination of competitive hydrogenation selectiv-
ity13 was confirmed in the above mentioned binary systems from values obtained for
other substrate pairs, based on the assumed validity of the following relation:
SAB SBC SCA = 1 .
(4)
As follows from the definition, Eq. (5) must hold:
S
AB = 1/SBA .
(5)
The product values appearing on the left-hand side of Eq. (4) are provided in Table IV.
A relatively great variance is partially caused by the product of the values subject to an
error of instrumentation, which was not here considered. It is necessary to realize that
the determination of selectivity values in binary systems formed by substrates
α-methylstyrene, 1-methylcyclohex-1-ene, 1-tert-butylcyclohex-1-ene on rhodium
catalyst is impossible. This is perhaps caused by specific interactions among the men-
tioned substrates on the catalytic surface, alternatively also to interactions among sub-
strates and molecules of the solvent from the bulk phase. Nevertheless, the relation (4)
can be applied, at least when used for rough selectivity assessments of values measured
independently for other alkene substrates of a similar structure type. Selectivity values
calculated in this way for binary mixture of 1-methylcyclohex-1-ene–3-tert-butylcyclo-
hex-1-ene, which could not be measured for the above given reasons, are after a calcu-
lation based on the relation (4), 1.14 for palladium catalyst, 0.93 for rhodium catalyst
and 1.32 for platinum catalyst. These values confirm the above conclusion, according
to which the effect of tert-butyl group in the α-position to the double bond of cyclo-
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

Competitive Catalytic Hydrogenation
TABLE IV
1923
Confirmation of feasibility of an indirect determination of competitive hydrogenation selectivities
Substrate A
B
C
SAB
SBC
SCA
SAB SBC SCA
Pd catalyst
Pt catalyst
Rh catalyst
α-Methylstyrene
Cyclohexene
1-Methylcyclohex-1-ene
1.68
1.68
29.0
16.8
16.8
1/29.0
1/508
1/508
1/394
0.97
1.30
1.27
0.95
α-Methylstyrene
Cyclohexene
1-tert-Butylcyclohex-1-ene
394
α-Methylstyrene
1-Methylcyclohex-1-ene
1-tert-Butylcyclohex-1-ene
22.2
22.2
Cyclohexene
1-Methylcyclohex-1-ene
1-tert-Butylcyclohex-1-ene
α-Methylstyrene
Cyclohexene
1-Methylcyclohex-1-ene
1.98
1.98
15.2
10.7
10.7
1/15.2
1/431
1/431
1/267
1.39
1.23
0.98
1.12
α-Methylstyrene
Cyclohexene
1-tert-Butylcyclohex-1-ene
267
α-Methylstyrene
1-Methylcyclohex-1-ene
1-tert-Butylcyclohex-1-ene
27.9
27.9
Cyclohexene
1-Methylcyclohex-1-ene
1-tert-Butylcyclohex-1-ene
α-Methylstyrene
Cyclohexene
1-Methylcyclohex-1-ene
1.04
1.04
25.3
1/26.5
1/257
0.99
0.99
α-Methylstyrene
244
Cyclohexene
1-tert-Butylcyclohex-1-ene
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

1924
Kacer, Laate, Cerveny:
TABLE IV
(Continued)
Substrate A
B
C
SAB
SBC
SCA
SAB SBC SCA
Rh catalyst
α-Methylstyrene
1-Methylcyclohex-1-ene
1-tert-Butylcyclohex-1-ene
26.5
10.7
25.1
1/257
2.59
1.10
Cyclohexene
25.1
1/244
1-Methylcyclohex-1-ene
1-tert-Butylcyclohex-1-ene
hexene skeleton is approximately concurrent with the effect of methyl group bonded
directly on the reaction center.
Competitive Hydrogenation in Ternary Systems
Ternary systems were formed by a substrate pair consisting of a bulky substituent on
the cyclohexene skeleton, 1-tert-butylcyclohex-1-ene or 3-tert-butylcyclohex-1-ene,
and a model alkene substrate, α-methylstyrene or cyclohexene, respectively. The re-
sults of performed experiments are presented in Table V. The selectivities were deter-
mined using straight line slopes, which were produced interpolating the experimental
data plotted in the Rader–Smith coordinates. A typical course is depicted in Fig. 1.
Addition of a third substance, capable of competitive adsorption on the catalytic sur-
0.0
c
–0.1
c
FIG. 1
–0.2
Competitive hydrogenation in ternary system 3-
tert-butylcyclohex-1-ene–1-tert-butylcyclohex-
1-ene–cyclohexene on Pd/C catalyst.
–0.3
−−−− Ternary system 1-tert-butylcyclohex-1-
ene–3-tert-butylcyclohex-1-ene–cyclohexene.
–0.4
.. ..
−
− − Binary system 1-tert-butylcyclohex-
–0.5
–0.6
1-ene–3-tert-butylcyclohex-1-ene after cyclo-
hexene vanishing from the reaction mixture.
− − − − Hypothetical reaction course in ternary
system.
–0.7
–0.030
.
.
− − − Binary system 1-tert-butylcyclohex-1-
ene–3-tert-butylcyclohex-1-ene
–0.020
–0.010
log (cA/cA0
0.000
)
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

Competitive Catalytic Hydrogenation
1925
face and not causing just a blocking of the surface, significantly affected not only hy-
drogenation rates of all the substrates, but notably altered selectivity values of the com-
petitive hydrogenations as well. As it is apparent from Table V, in all the ternary
systems on all the selected catalysts, a decrease in selectivity occurred in the 3-tert-
butylcyclohex-1-ene–1-tert-butylcyclohex-1-ene system (S(AB)C). After the fastest reac-
ting substrate, α-methylstyrene or cyclohexene vanished, a selectivity (SA′ B) increase
occurred which, within the frame of a variety of experimental data, returned to its
original value.
TABLE V
Changes in selectivity in transition from binary (3-tert-butylcyclohex-1-ene–1-tert-butylcyclohex-1-
ene) to ternary system (3-tert-butylcyclohex-1-ene–1-tert-butylcyclohex-1-ene–C)
′
SAB
SAB
Substrate C
Catalyst
S(AB)C
22.5 ± 1.8
22.5 ± 1.8
cyclohexene
Pd/C
Pd/C
19.3 ± 1.3
17.6 ± 1.2
23.3 ± 1.6
23.4 ± 1.2
α-methylstyrene
36.7 ± 1.2
36.7 ± 1.2
cyclohexene
Pt/C
Pt/C
32.6 ± 1.1
26.1 ± 1.7
35.9 ± 1.8
37.1 ± 1.1
α-methylstyrene
23.4 ± 1.4
22.5 ± 1.8
cyclohexene
Rh/C
Rh/C
19.3 ± 1.4
18.8 ± 1.6
23.3 ± 1.4
23.3 ± 1.6
α-methylstyrene
The authors acknowledge the Grant Agency of the Czech Republic for finantial support (grant No.
104/96/0445).
SYMBOLS
A
B
cA
cA0
f
substrate (substance to be hydrogenated)
substrate (substance to be hydrogenated)
concentration of substance A, mol dm–3
initial concentration of substrate A, mol dm–3
correlation coefficient
kA
rate constant of hydrogenation of substrate A
adsorption coefficient of substrate A
relative adsorption coefficient
rate of hydrogenation of substrate A, mol min–1
KA
KA/KB
rA
−1
g
cat
SAB
S(AB)C
SA′ B
selectivity of competitive hydrogenation of substrates A and B
selectivity of competitive hydrogenation of substrates A and B in presence of substance C
selectivity of competitive hydrogenation of substrates A and B after vanishing sub-
stance C from the reaction mixture
2
−1
SBET
total surface area, m g
cat
Collect. Czech. Chem. Commun. (Vol. 63) (1998)

1926
Kacer, Laate, Cerveny:
−1
SMET
t
V
w
metal surface area, mm2 etal
time, min
g
cat
volume of reaction mixture, dm3
weighed amount of catalyst, g
REFERENCES
1. Cerveny L., Ruzicka V.: Adv. Catal. 1981, 30, 335.
2. Kluson P., Cerveny L.: Appl. Catal., A 1995, 128, 13.
3. Cerveny L., Ruzicka V.: Catal. Rev.-Sci. Eng. 1982, 24, 503.
4. Kluson P., Kacer P., Cerveny L.: React. Kinet. Catal. Lett. 1996, 59, 2.
5. Dobrovolna Z., Kacer P., Cerveny L.: J. Mol. Catal. 1998, 130, 279.
6. Kacer P., Novak P., Cerveny L.: Unpublished results.
7. Jackson D. S., Shaw L. A.: Appl. Catal., A 1996, 134, 91.
8. Cabello J. A., Campelo J. M., Garcia A., Luna D., Marinas J. M.: J. Catal. 1985, 94, 1.
9. Lebedev S. V., Kobliansky G. G., Yakubchik A. O.: J. Chem. Soc. 1925, 127, 417.
10. Campbell K. N., Campbell B. K.: Chem. Rev. 1942, 31, 77.
11. van Bekkum H., Kieboom A. P. G., van der Putte K. J. G.: Rec. Trav. Chim. Pays-Bas 1969, 88, 52.
12. Cerveny L., Heral V., Marhoul A., Ruzicka V.: Chem. Listy 1974, 68, 1285.
13. Rader C. P., Smith H. A.: J. Am. Chem. Soc. 1962, 84, 1443.
Collect. Czech. Chem. Commun. (Vol. 63) (1998)