Kinetics of oxidation of lower olefins with Fe(III) aqua ions in the presence of the Pd/ZrO2/SO4 precatalyst in a chloride-free system

Article abstract of DOI:10.1134/S107036320606003X

The kinetics of oxidation of ethene, propene, and 1-butene with Fe(III) aqua ions to the corresponding carbonyl compounds in the presence of the 1% Pd/ZrO₂/SO₄ precatalyst in aqueous perchloric acid at 40-80°C was studied. The oxidation rate increases in the order C ₂H₄ < C₄H₈ < C ₃H₆ and with increasing catalyst weight and in the acid and Fe(III) concentrations; it is independent of the olefin pressure. The ethene oxidation rate is described by the Michaelis-Menten equation. In the case of 1-butene, the reaction is accompanied by migration of the double bond with the formation of 2-butene. Pleiades Publishing, Inc., 2006.

Full text of DOI:10.1134/S107036320606003X

ISSN 1070-3632, Russian Journal of General Chemistry, 2006, Vol. 76, No. 6, pp. 857 861.
Pleiades Publishing, Inc., 2006.
Original Russian Text V.V. Potekhin, V.A. Matsura, 2006, published in Zhurnal Obshchei Khimii, 2006, Vol. 76, No. 6, pp. 895 900.
Kinetics of Oxidation of Lower Olefins with Fe(III) Aqua Ions
in the Presence of the Pd/ZrO /SO Precatalyst
2
4
in a Chloride-Free System
V. V. Potekhin and V. A. Matsura
St. Petersburg State Institute of Technology (Technical University),
Moskovskii pr. 26, St. Petersburg, 198013 Russia
e-mail: potechin@mail.admiral.ru
Received May 31, 2005
Abstract The kinetics of oxidation of ethene, propene, and 1-butene with Fe(III) aqua ions to the cor-
responding carbonyl compounds in the presence of the 1% Pd/ZrO /SO precatalyst in aqueous perchloric acid
2
4
at 40 80 C was studied. The oxidation rate increases in the order C H < C H < C H and with increasing
2
4
4
8
3 6
catalyst weight and in the acid and Fe(III) concentrations; it is independent of the olefin pressure. The
ethene oxidation rate is described by the Michaelis Menten equation. In the case of 1-butene, the reaction is
accompanied by migration of the double bond with the formation of 2-butene.
DOI: 10.1134/S107036320606003X
Liquid-phase oxidation of unsaturated hydrocar-
bons to the corresponding carbonyl compounds in the
presence of a Pd-containing catalyst is of basic and
applied importance, and studies of these reactions
remain urgent [1 8].
Figure 1 shows that the maximal rate of olefin
oxidation with Fe(III) aqua ions in the presence of
Pd/ZrO /SO increases in the order C H < C H <
2
4
2
4
4
10
C H , and the rate ratio at 65 C is 1 : 1.4 : 3. The
3
6
higher rate of the oxidation of propene, compared to
that of ethene, is consistent with the increase in the
nucleophilic properties from ethene to propene. This
fact suggests that reaction (1) involves palladium
species in a higher oxidation state. In this case, the
rate of 1-butene oxidation should be still higher. How-
ever, this is not the case. With 1-butene, the oxidation
is accompanied by migration of the double bond with
the formation of 2-butene. In particular, at 55 C in
In [9, 10] we proved formation of palladium nano-
particles with a mean size of 5 nm and suggested that
these particles play a key role in the oxidation of
olefins with Fe(III) in an aqueous chloride-free system
in the presence of both homogeneous [Pd(II) tetraaqua
complex] and heterogeneous (Pd/ZrO /SO ) catalysts.
2
4
In this study we examined the kinetics of catalytic ox-
idation of ethene, propene, and 1-butene with Fe(III)
Volef, ml
aqua complex under the action of the Pd/ZrO /SO4
2
2
.4
precatalyst [reaction (1)]:
1
2
.0
2
H C=CHR + 2Fe(III) + H O
2
2
Pd/ZrO /SO
2
4
1.6
CH C(O)R + 2Fe(II).
(1)
3
3
1
.2
.8
The kinetic curves of the oxidation of ethene, prop-
ene, and 1-butene are shown in Fig. 1. In all the cases,
the reaction has an induction period in which the cata-
lytically active palladium nanoparticles, detected and
described in [10], are formed. The duration of the
induction period depends on the initial concentrations
of the components and the temperature. When study-
ing the effect of the system components on the reac-
tion kinetics, we took as a criterion the maximal reac-
tion rate attained immediately after the completion of
the induction period.
0
0
.4
0
1
0 20 30 40 50 60 70 80 90
Time, min
Fig. 1. Kinetic curves of the oxidation of olefins with
Fe(III) aqua ions in the presence of Pd/ZrO /SO
(40 mg). [Fe
and (3) C H .
2
4
3
+
] 0.03 M, 65 C. (1) C H , (2) C H ,
aq
0 2 4 3 6
4
8
857

858
POTEKHIN, MATSURA
7
0 min, 30% of 1-butene is converted to 2-butene
(10% into cis-2-butene and 20% into trans-2-butene),
1
2
and only 3% of 1-butene is oxidized with the forma-
tion of methyl ethyl ketone.
1
0
8
6
We found that 1-butene does not isomerize into
2-butene on sulfated zirconium oxide in aqueous per-
chloric acid solution in the presence of Fe(III). The
migration of the double bond occurs only in the pres-
ence of Pd/ZrO /SO and Fe(III). It is believed that
2
4
4
2
the migration of the double bond in the olefin is cata-
lyzed by palladium in an intermediate oxidation state
[5, 11]. The positional isomerization we observed sug-
0
gests the occurrence of reactions in which Pd(0) from
Pd/ZrO /SO transforms into an intermediate oxida-
tion state catalyzing the isomerization. Partial isomeri-
zation of 1-butene into 2-butene apparently explains
slower oxidation of butene compared to propene. It is
known that 2-butene is oxidized less readily than
1-butene [4, 5].
0
.02 0.04 0.06 0.08 0.10 0.12
Precatalyst weight, g
2
4
Fig. 2. Initial rate of ethene oxidation by reaction (1) as
a function of the precatalyst weight. [Fe
3
+
] 0.03 and
0
aq
[
HClO ] 0.4 M; P(C H ) 0.1 MPa; 65 C.
4 2 4
In this study the majority of kinetic experiments
were performed with ethene.
8
As seen from Figs. 2 4, the dependences of the
ethene oxidation rate on the amounts of the precata-
lyst, Fe(III), and perchloric acid have a complex shape
and are described by curves with saturation, which are
linearized in the Lineweaver Burk coordinates as
applied to the Michaelis Menten rate equation.
6
4
2
0
Unexpectedly, the oxidation appeared to be zero-
order with respect to the ethene partial pressure. Ap-
parently, the ethene oxidation step proper is preceded
by a slow step of a certain catalytic redox reaction.
0
.01 0.02 0.03 0.04 0.05 0.06
3
+
[
Fe ] , M
aq 0
With a decrease in the initial partial pressure of
ethene, the reaction deceleration with time becomes
more pronounced (Fig. 5).
Fig. 3. Initial rate of ethene oxidation as a function of
the initial Fe(III) concentration. Precatalyst weight
4
0 mg; [HClO ] 0.4 M; P(C H ) 0.1 MPa; 65 C.
4 2 4
Thus, the rate equation of reaction (1) for ethylene
has the form
8
7
6
5
3+
[
Fe ]
aq 0
Pd
[HClO4]
0
w = k
[C H ] ,
2 4
3+
K + [Pd] K + [Fe ] K + [HClO ]
aq 0
4
where k 3.5 10 5 mol l s ; K 3.8 10 , K 0.03,
and K 0.1 mol l 1 at 65 C; [Pd] denotes the total
amount of Pd (moles) in the precatalyst Pd/ZrO /SO
1
1
4
4
3
2
1
0
2
4
taken for the reaction in the unit volume of the solu-
tion.
The temperature dependence of the rate constant k
is complex. The Arrhenius plot of the ethene oxida-
tion rate has a bend. In the range 40 55 C, the activa-
tion energy is 69 7 kJ mol , and at 55 75 C, 141
14 kJ mol . The bend suggest a change in the struc-
0
.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
HClO ], M
[
4
1
Fig. 4. Initial rate of ethene oxidation as a function of
the perchloric acid concentration. Precatalyst weight
0 mg; [Fe
1
3
+
4
]0 0.03 M; P(C H ) 0.1 MPa; 65 C.
ture and energy state of active palladium centers at the
aq
2 4
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 6 2006

KINETICS OF OXIDATION OF LOWER OLEFINS WITH Fe(III) AQUA IONS
859
corresponding temperature [12]. At higher tempera-
tures (55 75 C), the number of active centers in-
creases, and their potential energy decreases. As a re-
sult, the activation energy of the catalytic reaction
increases in accordance with the theory of active
centers.
particles interact with such centers, forming an adduct
+
[Pd H]
[16] in which Pd particles acquire a
x + (1 )x+
fractional positive charge, [Pdn Hx
] .
aq
H
O
Zr
^^^^^^^^^^^^^^^^^
[ +
Pd H(1
)+
] .
aq
Pd
The apparent activation energy of the oxidation of
^
propene and 1-butene at 55 75 C is 83 8 and 99
1
9
kJ mol , respectively.
We found previously that palladium particles in the
intermediate oxidation state can be oxidized with
Fe(III) aqua ions [17, 18]. It is known that the particle
size of Pd determines its redox properties [19]. Appar-
ently, in the adduct the palladium nanoparticles exhib-
it sufficient reducing power to be oxidized with Fe(III)
aqua ions with the formation of oxidized palladium
species. Data on the partial oxidation of metallic Pd
atoms in a Pd cluster with Fe(III) aqua ions with the
formation of Pd species in an intermediate oxidation
state are reported in [20]. The reaction of the Pd
adduct with Fe(III) aqua ions yields Pd species in an
intermediate oxidation state, +1:
The lack of the influence of the ethene pressure on
the oxidation rate does not allow reaction (1) to be
considered as a purely heterogeneous reaction involv-
ing adsorption of an unsaturated hydrocarbon on the
catalyst surface followed by its oxidation. The rate
equation of the ethene oxidation suggests that the car-
bonyl compound is formed from the olefin after the
limiting step and that the limiting step is apparently
the transfer of palladium particles from the surface of
the solid catalyst to solution with the formation of
palladium nanoparticles, followed by their oxidation
with Fe(III) aqua ions.
x + (1
)x+]aq + Fe3+
[Pdn 1Pd+]aq + Fe + H , (2)
2+
+
[
Pd
H
The possible transfer of platinum group metals
from the finely dispersed state in a metallic catalyst
to solution under the action of protons is discussed in
n
x
aq
aq
2+
2+
[
Pdn 1Pd+]aq + Fe3+
aq
[Pdn 2Pd ] + Fe . (3)
2
aq
aq
[
13 15]. Apparently, hydroxonium ions in the reac-
In the subsequent process, the olefin is rapidly
tion solution promote the transfer of palladium nano-
particles from the precatalyst surface to solution, as
suggested by an increase in the olefin oxidation rate
with an increase in the acid concentration.
2
+
oxidized on the active center of the [Pdn Pd ]
2
2
aq
particles to the corresponding carbonyl compound via
formation of a palladium vinyl compound or of a
allyl complex (in the case of propene and 1-butene).
-
In an aqueous medium, Brønsted acid centers are
formed on the support surface. Metallic palladium
After reaction (4), the catalytic cycle is repeated.
CH =CH2
2
[Pd Pd]n 2 Pd+ Pd+
[
Pd Pd]n 2 Pd+ Pd+ + CH =CH2
2
CH =CH2 2
2
+
H
H O
2
+
[
Pd Pd Pd Pd ] + CH C(O)H + 2H
[
Pd Pd]n 2 Pd Pd
n
3
(4)
2
+
[
Pd Pd]n 2 Pd+ Pd+
+
[Pd Pd]n 2 Pd Pd
[
Pd Pd]n 2 Pd+ Pd+
+
2
+
H
Pd Pd]n 2 Pd Pd
[
+
[
Pd Pd Pd Pd ] + CH C(O)CH CH + 2H
n 3 2 3
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 6 2006

860
POTEKHIN, MATSURA
2
.8
3
2
.0
.5
1
1
2
2
.4
2
2
1
.0
.6
3
2
.0
4
1
1
0
.5
.0
1
0
0
.2
.8
3
.5
0
.4
0
10
20
30
40
50
10
20 30 40 50 60 70
Time, min
Time, min
Fig. 5. Influence of the ethene partial pressure on its
Fig. 6. Influence of the Fe(II) concentration on the ethene
3
+
oxidation. Precatalyst weight 10 mg; [Fe
]0 0.03 and
oxidation in the system 1% Pd/ZrO /SO Fe(III) . Pre-
aq
2
4
aq
3
+
[
HClO ] 0.4 M; 65 C. P(C H ), MPa: (1) 0.1, (2) 0.05,
catalyst weight 40 mg; [Fe
] 0.03, [HClO ] 0.4 M;
4
2
4
aq
0 4
2
+
(
3) 0.025, and (4) 0.015.
73 C. [Fe
] , M: (1) 0, (2) 0.03, and (3) 0.06.
aq
0
The oxidation of palladium nanoparticles with
in the reaction of olefins with Pd(II) tetraaqua com-
plex. Therefore, the formation of -allyl complexes
on active palladium centers in the case of propene and
1-butene can also be responsible for a decrease in the
oxidation rate. As seen from Fig. 1, the reaction decel-
eration observed in the kinetic curves of the oxidation
of propene and 1-butene is more abrupt compared to
the oxidation of ethene.
Fe(III) aqua ions [reaction (2)] is influenced by the
Fe(II) concentration. Addition of Fe(II) aqua ions to
the initial reaction system makes the induction period
longer (Fig. 6) and decelerates the overall reaction of
the olefin oxidation. The maximal oxidation rate is
inversely proportional to the initial Fe(II) concentra-
toin.
We estimated kinetically the steady-state concen-
tration of palladium in solution in oxidation of ethene
with Fe(III) in the presence of Pd/ZrO /SO . To this
Apparently, the effect of Fe(II) is caused by the
equilibrium character of the reaction between the Pd
nanoparticles and Fe(III) aqua ions. The equilibrium
character of reaction (2) is also confirmed by the in-
fluence of the initial Fe(III) concentration on the
ethene oxidation rate. As the concentration ratio of the
arising Fe(II) and remaining Fe(III) reaches a definite
value, the reaction always decelerates. In particular,
in the oxidation of ethene at 65 C, the Fe(II)/Fe(III)
ratio is close to 1 : 2 and is independent of the initial
Fe(III) concentration.
2
4
end, we chose as the reference reaction the oxidation
+
2
of ethene with vanadate ion (VO ) under similar con-
ditions. Preliminary experiments showed that vanadate
ion quantitatively oxidized Pd(0) to Pd(II) on contact
with Pd/ZrO /SO . Therefore, the oxidation of ethene
2
4
with vanadate ion in the presence of Pd/ZrO /SO
2
4
can be considered as a catalytic reaction with respect
to Pd(II). For example, at the initial weight of the
Pd/ZrO /SO catalyst of 1 mg, which corresponds to
2
4
The Fe(II) aqua ions arising in the course of the
olefin oxidation compete with the unsaturated hydro-
carbon for the active Pd center, the competition be-
coming particularly pronounced at low olefin pres-
sures (Fig. 5). Therefore, the Fe(III) conversion usu-
ally does not reach 100%. With an increase in the
temperature, the Fe(III) conversion increases. For
example, in the ethene oxidation, the Fe(III) conver-
sion was 47% at 50 C and 90% at 75 C.
5
the 10 M concentration of Pd(II) in the solution after
the oxidation with vanadate ion (0.06 M), the rate of
6
1
1
ethene oxidation at 65 C is 7.4 10 mol l s .
With Fe(III), at its similar initial concentration
(
0.06 M), the same rate of ethene oxidation is attained
with 40 mg of the Pd/ZrO /SO catalyst. This fact
2
4
suggests that, in the course of ethene oxidation with
Fe(III) aqua ions in the presence of Pd/ZrO /SO ,
2
4
2.5% of Pd transforms into the active species.
According to [21, 22], in the presence of Fe(III)
aqua ions the formation of palladium -allyl com-
plexes prevails over the oxidative transformation of
olefins into the corresponding carbonyl compounds
Thus, the transfer of palladium nanoparticles into
solution from the surface of the supported Pd metal
catalyst Pd/ZrO /SO , promoted by protons of the
2
4
medium and acid base properties of the support,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 6 2006

KINETICS OF OXIDATION OF LOWER OLEFINS WITH Fe(III) AQUA IONS
861
creates conditions for the catalytic oxidation of
olefins with Fe(III) aqua ions, similarly to the Wacker
process but in the absence of chloride ions.
2. Mijs, W.J., Organic Syntheses by Oxidation with
Metal Compounds, New York: Academic, 1986.
3. Heck, R.F., Palladium Reagent in Organic Syntheses,
New York: Academic, 1985.
EXPERIMENTAL
4. Maitlis, P.V., The Organic Chemistry of Palladium,
New York: Academic, 1971, vol. 2.
The procedure for preparing the Pd/ZrO /SO4
precatalyst was described in [10]. The Pd content in
the sample was 1 wt %. Ethene, propene, and 1-butene
5. Tsuji, J., Palladium Reagents and Catalysts, England:
Wiley, 1995.
6. Moiseev, I.I. and Vargaftik, M.N., Catalysis with
Palladium Clusters, Adams, R.A. and Cotton, F.A.,
Eds., New York: Wiley, 1998, ch. 12.
2
(
Aldrich) were 99% pure. Iron(III) was added to the
reaction solution in the form of Fe (SO ) 9H O (an
2
4 3
2
aliquot of a solution in perchloric acid). The Pd(II)
concentration was determined spectrophotometrically
from the intensity of the green color of the complex
7. Lambert, E., Derouane, G., and Kozhevnikov, I.V.,
J. Catal., 2002, vol. 211, no. 8, p. 445.
8. Zhizhina, E.G., Simonova, M.V., Odyakov, V.F., and
Matveev, K.I., React. Kinet. Catal. Lett., 2003,
vol. 80, no. 2, p. 171.
obtained on adding an excess of a SnCl solution to
2
a sample of the reaction solution [23]. The Fe(III)
concentration was also determined spectrophotometri-
cally (with sulfosalicylic acid [24]).
9. Potekhin, V.V. and Matsura, V.A., Zh. Obshch. Khim.,
2005, vol. 75, no. 9, p. 1508.
1
1
1
0. Potekhin, V.V. and Matsura, V.A., Izv. Ross. Akad.
Nauk, Ser. Khim., 2006, no. 6, p. 1231.
1. Temkin, O.N. and Bruk, L.G., Usp. Khim., 1983,
vol. 52, no. 2, p. 206.
2. Panchenkov, G.M. and Lebedev, V.P., Khimicheskaya
kinetika i kataliz (Chemical Kinetics and Catalysis),
Moscow: Khimiya, 1985.
3. Shi, H., Bi, H., Yao, B., and Zhang, L., Appl. Surf.
Sci., 2000, vol. 161, no. 3, p. 276.
4. Dissanayake, D. and Lunsford, J., J. Catal., 2002,
vol. 206, no. 2, p. 173.
The partial pressure of ethene was varied by its
dilution with Ar. In all the cases, the total gas pressure
was 0.1 MPa.
The kinetic experiment was performed as follows.
A weighed portion of Pd/ZrO /SO was added to a
2
4
solution of Fe(III) in HClO of the required concen-
4
1
1
1
tration. The volume of the reaction solution was 10 ml
in all the experiments. The reaction was performed on
a volumetric unit in a temperature-controlled duck-
shaped vessel at temperatures from 40 to 80 C with
shaking; the reaction progress was monitored by
measuring the olefin uptake. In preliminary experi-
ments we determined the shaking frequency above
which the reaction rate remained constant, i.e., the
reaction was kinetically controlled. For comparison,
we also performed test reactions with magnetic stir-
ring at 1200 rpm and obtained similar reaction rates.
The oxidation products were extracted from aqueous
solutions with chlorobenzene and analyzed by gas
chromatography mass spectrometry (HP-5890GCD
instrument equipped with a 30-m HP-5 column).
5. Ivanov, A.V. and Kustov, L.M., Izv. Ross. Akad. Nauk,
Ser. Khim., 1998, no. 1, p. 57.
16. Stakheev, A. and Kustov, L., Appl. Catal. A: General,
1999, vol. 188, no. 1, p. 3.
17. Potekhin, V.V., Solov’eva, S.N., and Potekhin, V.M.,
Izv. Ross. Akad. Nauk, Ser. Khim., 2003, no. 12,
p. 2525.
18. Potekhin, V.V., Matsura, V.A., Solov’eva, S.N., and
Potekhin, V.M., Kinet. Katal., 2004, vol. 45, no. 3,
p. 407.
1
9. Jana, N., Wang, Z., and Pal, T., Langmuir, 2000,
vol. 16, no. 10, p. 2457.
20. Ebitani, K., Choi, K.-M., Mizugaki, T., and Faneda, K.,
The products of the positional isomerization of
-butene were analyzed by H NMR spectroscopy
Bruker DPX-300 spectrometer) upon saturation of the
1
1
(
Langmuir, 2002, vol. 18, no. 8, p. 1849.
2
2
1. Potekhin, V.V., Ryadinskaya, N.Yu., and Pote-
khin, V.M., Zh. Obshch. Khim., 2001, vol. 71, no. 8,
p. 1242.
2. Ryadinskaya, N.Yu., Potekhin, V.V., Skvortsov, N.K.,
and Potekhin, V.M., Zh. Obshch. Khim., 2002, vol. 72,
no. 6, p. 1004.
solvent (CDCl ) with the gaseous catalyzate after the
3
reaction completion, and also by gas chromatography
mass spectrometry (Agilent 6890/5973 Network
000 250 5 device, determination of the compo-
1
sition of the gas phase in the reactor).
REFERENCES
23. Ginzburg, S.I., Analiticheskaya khimiya platinovykh
metallov (Analytical Chemistry of Platinum Metals),
Moscow: Nauka, 1972.
24. Marczenko, Z., Kolorymetryczne oznaczanie pier-
wiastkow, Warsaw: Naukowa-Techniczne, 1968.
1
. Moiseev, I.I., -Kompleksy v zhidkofaznom okislenii
olefinov ( Complexes in Liquid-Phase Oxidation of
Olefins), Moscow: Nauka, 1970.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 76 No. 6 2006