Highly selective catalysts for liquid-phase hydrogenation of substituted alkynes based on Pd—Cu bimetallic nanoparticles

Article abstract of DOI:10.1007/s11172-016-1316-0

Catalytic properties of Pd—Cu bimetallic catalysts supported on SiO₂ and Al₂O₃ were studied in a model reaction of selective hydrogenation of diphenylacetylene. Application of PdCu₂(AcO)₆ heterobimetallic acetate complex as a precursor made it possible to obtain homogeneous Pd—Cu bimetallic nanoparticles. This result was supported by the data of IR spectroscopy of adsorbed CO. The Pd-Cu catalysts showed considerably higher selectivity than monometallic samples. Moreover, the introduction of copper decreases the hydrogenation rate of diphenylethylene (DPE) to diphenylethane. As a result, the maximum yield of the target product, DPE, increased from 78 to 93% in the presence of Pd—Cu catalysts.

Full text of DOI:10.1007/s11172-016-1316-0

Russian Chemical Bulletin, International Edition, Vol. 65, No. 2, pp. 425—431, February, 2016
425
Highly selective catalysts for liquidꢀphase hydrogenation
of substituted alkynes based on Pd—Cu bimetallic nanoparticles
I. S. Mashkovsky,a P. V. Markov,a G. O. Bragina,a O. P. Tkachenko,a I. A. Yakushev,b
N. Yu. Kozitsyna,b M. N. Vargaftik,b and A. Yu. Stakheeva
аN. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Eꢀmail: st@ioc.ac.ru
bN. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
31 Leninsky prosp., 119991 Moscow, Russian Federation.
Catalytic properties of Pd—Cu bimetallic catalysts supported on SiO2 and Al2O3 were
studied in a model reaction of selective hydrogenation of diphenylacetylene. Application of
PdCu2(AcO)6 heterobimetallic acetate complex as a precursor made it possible to obtain hoꢀ
mogeneous Pd—Cu bimetallic nanoparticles. This result was supported by the data of IR specꢀ
troscopy of adsorbed CO. The PdꢀCu catalysts showed considerably higher selectivity than
monometallic samples. Moreover, the introduction of copper decreases the hydrogenation rate
of diphenylethylene (DPE) to diphenylethane. As a result, the maximum yield of the target
product, DPE, increased from 78 to 93% in the presence of Pd—Cu catalysts.
Key words: bimetallic catalysts, Pd, Cu, hydrogenation, alkynes, diphenylacetylene.
The selective catalytic hydrogenation of alkynes is one
of the most important reactions since it serves to produce
cisꢀ and transꢀalkenes which could be used as building
blocks on different stages of fine organic synthesis.1—3
Pdꢀsupported catalysts characterized by a high hydrogeꢀ
nation activity are commonly used in selective hydrogenaꢀ
tion reactions. However, a high rate of the hydrogenation
of target alkene to alkane decreases the selectivity of the
process.4
At present, a commercial Lindlar catalyst (Pd(5%)—
PbO/CaCO3) is widely applied for the cisꢀalkene syntheꢀ
sis from alkynes. Despite its high selectivity, an essential
disadvantage is the presence of toxic lead compounds in
its structure which are required for a partial deactivation
of the catalyst to avoid overhydrogenation and alkane forꢀ
mation. Moreover, the catalyst can not be used for hydroꢀ
genation of a number of substrates (therminal alkynes as
an example)2 and it is not always stable under the reaction
conditions.5
An efficient approach for development of a selective
catalyst for С≡С bond hydrogenation involves using bimeꢀ
tallic Pd—M compositions, where М = Ag, Zn, Cu, etc.6
According to the literature, modification of Pd catalysts
with silver7,8, zinc9,10, gold11,12 or copper 13,14 provides an
improved selectivity in alkene formation. A special interꢀ
est evoke bimetallic Pd—Cu complexes, because modifiꢀ
cation with copper increases the selectivity both in gas
phase and liquid phase reactions.13—15
However, to prepare a highly selective catalyst, homoꢀ
geneous bimetallic particles which do not contain Pd0
need to be formed on the support surface. Such particle
formation is not always achieved when traditional catalyst
preparation methods are used. At the same time applicaꢀ
tion of heterobimetallic acetate complexes of palladium
with a second metal as precursor is one of the most effecꢀ
tive technique to prepare highly homogeneous bimetallic
catalyst.9,16,17 In such complexes atoms of the both metꢀ
als are strongly bounded by acetate bridges that allow them
to keep the intimate contact on every step of the preparaꢀ
tion and activation of the catalyst providing bimetallic
nanoparticle formation in the final catalyst.16,17. In the
present work, an approach referred to above was applied
for preparing Pd—Cu catalyst for the liquid phase selecꢀ
tive hydrogenation of substituted alkynes. In order to deꢀ
termine the influence of the support on catalytic properꢀ
ties and structure, silica (SiO2) and alumina (Al2O3) were
used to prepare both monoꢀ and bimetallic samples. Cataꢀ
lytic characteristics of these systems were investigated in a
model reaction of diphenylacetylene (DPA) hydrogenation.
The selective hydrogenation of the substituted alkynes
operates in two steps (Scheme 1). At the first step, alkyne
hydrogenates mainly to alkene, while at the second step
the formed alkene hydrogenates to alkane which is undeꢀ
sirable process. Therefore it is necessary to minimize
the rate of the second reaction step. So the hydrogenaꢀ
tion rate ratio at the first and the second steps is an imporꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 0425—0431, February, 2016.
1066ꢀ5285/16/6502ꢀ0425 © 2016 Springer Science+Business Media, Inc.

426
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 2, February, 2016
Mashkovsky et al.
Scheme 1
transꢀDPE
rDPA
DPET
DPA
rDPA
cisꢀDPE
Cat is catalyst, DPE is diphenylethylene, DPET is diphenylethane.
tant characteristic1 which was carefully controlled in this
study.
The rates of the first and second reaction steps (rDPA and
rDPE respectively) were determined from the slope of the curve
obtained by plotting hydrogen uptake versus reaction time in the
H2/DPA range from 0.2 to 0.60 for the first step and from 1.1 to
1.5 for the second step and normalized to 1 mg of the catalyst
Experimental
(mmol H2 min–1 (mgcat –1).
)
Catalyst preparation. The catalysts Pd(1%)—Cu(1.2%)/
Al2O3 and Pd(1%)—Cu(1.2%)/SiO2 were prepared by the incipꢀ
ient wetness impregnation. The supports (γꢀAl2O3, Sasol,
150 m2 g–1; SiO2, Merck, 675 m2 g–1) were impregnated with a
PdCu2(AcO)6 solution17 in diluted acetic acid (pH 2.8). The
catalysts were dried in air, calcined (air, 550 °С, 2 h) and reꢀ
duced (H2(5%)/Ar, 550 °C, 1 h). For the FTIR characterization
the samples were prepared with a higher content of the active
components (Pd(3%)—Cu(3.6%)).
The monometallic catalysts containing 0.5% Pd and 3% Cu
were prepared by the incipient wetness impregnation of the supꢀ
port with an aqueous solution of [Pd(NH3)4](NO3)2 and
Cu(NO3)2 respectively. The samples were dried at ~20 °C and
then calcined and reduced under the same conditions as the
bimetallic catalysts. For the accurate comparison of the data at
close hydrogenation rates, an amount of the active component
in monometallic Pd catalysts was diminished to 0.5 wt.% as it is
significantly more active in the studied reaction compared to the
bimetallic sample.
Hydrogenation of diphenylacetylene (DPA). The liquid phase
hydrogenation of DPA was carried out in the autoclaveꢀtype
reactor equipped with a magnetic stirrer, an electron pressure
sensor and gas dosing and liquid phese sampling systems. Comꢀ
mercial nꢀhexane was used as a solvent. The experiments were
carried out at 25 °C and initial hydrogen pressure of 10 bar. The
kinetic regime was monitored according to the earlier described
procedure.15
The gas chromatographyꢀmass spectrometer Maestroꢀ2 (Inꢀ
terlab, Russia) was used for the analysis of the reaction mixture.
The separation was performed on HP5ꢀMS column (phenyldiꢀ
methylsiloxane (5%)) of 30 m in length, with the inner diameter
of 0.25 mm and thickness 0.25 μm. The gas carrier was helium
and an electron beam was used as a method of ionization, 70 eV.
The spectra were processed using the MSD ChemStation softꢀ
ware and NIST14 spectra library.
The catalytic activity was evaluated by the turnover frequenꢀ
cies (TOF). In the case of the bimetallic systems it is hardly
possible to determine the number of Pd surface atoms from the
electron microscopy data as the surface could be occupied by the
copper atoms. For this reason the value of TOF was calculated at
the first (TOFDPA) and second (TOFDPE) hydrogenation steps as
the ratio of the number of converted substrate (DPA or DPE) moꢀ
lecules to the total number of Pd atoms in the catalyst per second.
The selectivity to diphenylethylene (SDPE) was determined
using the data of GC/MS analysis of the reaction mixture:
SDPE = nDPE/(nDPE+ nDPET).
The efficiency of the kinetic process monitoring was estiꢀ
mated by comparing the ratio of the hydrogenation rates of dipheꢀ
nylacetylene (rDPA) and diphenylethylene (rDPE).13
Catalyst characterization. Electron microscopy. The microꢀ
structure of the catalysts was studied by field emission scanning
electron microscopy (FEꢀSEM) on a Hitachi SU8000 microꢀ
scope. Images were acquired in the secondary electron imaging
mode at an accelerating voltage of 2 kV and at a working disꢀ
tance of 4—5 mm. The optimization of the measurements was
employed according to the earlier described procedure.18 Before
the measurements, the samples were placed on the surface of a
round aluminum holder of 25 mm in diameter, fixed with adheꢀ
sive tape strips and coated with the conducting metal film (Au/
Pd, 60/40) using the the magnetron sputtering method as deꢀ
scribed elsewhere.19 The morphology of the samples was studied
considering the surface effects of the supported metal film.
IR Spectroscopy of Adsorbed CO. The diffuse reflectance IR
spectra of carbon monoxide were recorded on a Protege 460
spectrometer (Nicolet, United States) in the 400—6000 cm–1
range at a resolution of 4 cm–1. Carbon monoxide was used as
a probe molecule. The sample was placed in a glass vial equipped
with an appendix having a calcium ftoride window. Before reꢀ

Alkynes hydrogenation of substituted alkynes
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 2, February, 2016
427
cording the spectra, the samples were alternately evacuated and
treated with Н2 (30 Torr) at 450 °C for 2 h to remove adsorbed
gases and water from the surface, as well as for postreduction
(heat rate ~3.5 °C min–1). CO adsorbtion was performed at
~20 °C and pressure 20 Torr. CO desorption was carried out
under the vacuum with temperature gradually increased from 25
to 100 °С (heating rate ~8 °C min–1) for 1 h until a desired
temperature was achieved. The spectra of adsorbed CO were
presented as the difference between the spectra recorded before
and after adsorption of probe molecule.
catalyst, which contains the nanoparticles with the mean
size of ~5.1 nm.
Catalyst performance. The kinetic plots of the hydroꢀ
gen uptake vs. the reaction time in DPA hydrogenation
are shown in Fig. 2. The observed results are in a good
agreement with the literature data.20—22 The form of the
curves corresponds to the traditional mechanism of conꢀ
sequent hydrogenation, which is especially evident in a
noticeable bend in the range of hydrogen uptakes correꢀ
sponding to the molar ratio Н2 : DPA = 1. The initial
segment of the kinetic curve (Н2/DPA < 1) corresponds to
the first hydrogenation step (conversion DPA → DPE).
With an increase in the Н2/DPA ratio (>1) hydrogen upꢀ
take becomes slower indicating the transition from the
first to the second reaction step (conversion DPE →
DPET). The calculated kinetic characteristics of the cataꢀ
lysts are presented in Table 1.
Results and Discussion
Electron microscopy. Pd nanoparticles with the mean
size of ~2.9 nm are readily seen in the image of the monoꢀ
metallic Pd/Al2O3 catalyst (Fig. 1, a). When supported on
SiO2 bigger Pd particles are formed with an increased mean
particle size close to 3.5 nm (Fig. 1, b).
Over the monometallic sample Pd/Al2O3 the reacꢀ
Application of PdCu2(AcO)6 complex as a metal preꢀ
cursor (Fig. 1, c, d) increases the metal particle size comꢀ
pared to that in the monometallic catalyst. So, the mean
particle size increases to ~4.1 nm in the Pd—Cu/Al2O3
sample. A similar effect is observed for the Pd—Cu/SiO2
tion at the first step proceeds with a high rate (rDPA
= 27.4•10–3 mmol Н2 min–1 (mgcat –1) which decreases
to ~7.0•10–3 mmol Н2 min–1 (mgcat
=
)
–1
)
at the transiꢀ
tion to the second step of hydrogenation. Thus, the rate
a
b
50 nm
50 nm
c
d
50 nm
50 nm
Fig. 1. STEM images for the Pd(0.5%)/Al2O3 (a), Pd(0.5%)/SiO2 (b), Pd(1%)—Cu(1.2%)/Al2O3 (c) and Pd(1%)—Cu(1.2%)/SiO2 (d)
catalysts.

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Russ.Chem.Bull., Int.Ed., Vol. 65, No. 2, February, 2016
Mashkovsky et al.
AH /mol Н2 (mol DPA)–1
A decrease in the reaction rate is more pronounced for
the Cu containing catalyst supported on SiO2 than for the
2
2.0
catalyst supported on Al2O3 (see Fig. 2). The rate values
1
–1
are 1.89•10–3 and 0.07•10–3 mmol Н2 min–1 (mgcat
)
for the first and the second reaction step correspondingly.
As a result, a higher rDPA/rDPE ratio (~26) is observed in
comparison with the monometallic Pd/SiO2 catalyst. The
drastic decrease in the reaction rate over Pd—Cu/SiO2
can be affected by the support nature. Another reason is
that bigger bimetallic particles are formed in the Pd—Cu/
SiO2 catalyst than in the Pd—Cu/Al2O3 catalyst.
1.6
2
1.2
0.8
0.4
3
4
A detailed analysis of the reaction products obtained
over the monoꢀ and bimetallic catalysts supported on
Al2O3 shows that copper introduction remarkably increases
the selectivity in formation of the target product of semiꢀ
hydrogenation (Fig. 3). A volcanoꢀtype dependence of
DPE concentration on the reaction time confirms the conꢀ
sequent mechanism of DPA hydrogenation to DPE folꢀ
lowed by DPE conversion to DPET. Over the monomeꢀ
tallic catalysts a noticeable amount of DPET (10—15%)
is formed at the first reaction step when the concentration
of the initial DPA in the reaction mixture is high enough.
After the complete conversion of DPA, DPET concentraꢀ
tion reaches 25—30% (see Fig. 3, a, c). Over the bimetalꢀ
lic Pd—Cu catalysts (see Fig. 3, b, d) the traces of DPET
appear only in the range of high DPA conversion and do
not exceed 5—8% at the complete DPA hydrogenation.
As the DPET formation rate and, consequently, a fraction
of the complete hydrogenation products decrease, the
maximum yield of DPE increases from 78 to 93% for Pd—
Cu/Al2O3 and from 78 to 85% for Pd—Cu/SiO2.
The dependence of selectivity in DPE formation on
DPA conversion for the monoꢀ and bimetallic catalyst is
shown in Figure 4. It can be seen that by modifying the
catalyst with copper it is possible to considerably increase
the selectivity of the both Al2O3ꢀ and SiO2ꢀsupported catꢀ
alysts. This provides the evidence that the observed effect
is nearly independent of the nature of the support. Neverꢀ
theless, from the practical point of view, an enhanced
selectivity with respect to DPE from 85 to 95% in the
region of high DPA conversion can be considered as the
most important result.
50
100
150
200 τ/min
Fig. 2. The kinetic curves of hydrogen uptake in the liquidꢀphase
hydrogenation of DPA over the monoꢀ and bimetallic catalysts:
Pd(0.5%)/Al2O3 (1), Pd(1%)—Cu(1.2%)/Al2O3 (2), Pd(0.5%)/
SiO2 (3), Pd(1%)—Cu(1.2%)/SiO2 (4): P(H2) = 10 bar, T = 25 °С,
[DPA] = 0.159 mol L–1, mcat = 2.5 mg, solvent is nꢀhexane.
ratio rDPA/rDPE, which characterizes the kinetic selectivity
is ~3.9.
The rate of the hydrogenation of DPA over Pd/SiO2
is noticeably lower (3.09•10–3 mmol Н2 min–1 (mgcat
and on going to the second step it decreases to
0.2•10–3 mmol Н2 min–1 (mgcat –1, that leads to a rate
ratio value of ~15.2. A higher value rDPA/rDPE over
Pd/SiO2 can be partly explained by formation of the large
Pd nanoparticles in this sample. In our earlier studies12,23
it was shown that an increase in Pd nanoparticle size from
2 to 8 nm remarkably increases the ratio rDPA/rDPE in the
liquid phase hydrogenation of alkynes.
–1
)
)
After the catalyst Pd/Al2O3 was modified with copper,
the rate of the first step of hydrogenation over Pd—Cu
catalyst became somewhat lower than that observed over
the monometallic sample. At the second step, reaction
rate over Pd—Cu/Al2O3 noticeably decreases (from
16.46•10–3 to 0.29•10–3 mmol Н2 min–1 (mgcat –1).
)
Changing the shape of the kinetic curves can be clearly
seen (see Fig. 2) with a visible bend in the range of hydroꢀ
gen uptake Н2 equal to ~1. In addition, the rate ratio
increases 14 times (to ~57).
IRꢀspectroscopy of the adsorbed CO. The state of the
metals in the catalysts was estimated using IR spectra of
adsorbed CO (Fig. 5). In the spectra of Pd(0.5%)/Al2O3
Table 1. The kinetic characteristics of the monoꢀ and bimetallic catalysts in the selective liquidꢀphase DPA
hydrogenation
Сatalyst
rDPA•103
rDPE•103
TOFDPA
TOFDPE
rDPA/rDPE
–1
mmol Н2 min–1 (mgcat
)
s–1
Pd(0.5%)/Al2O3
Pd(1%)—Cu(1.2%)/Al2O3
Pd(0.5%)/SiO2
27.38
16.46
3.09
6.98
0.29
0.2
9.71
2.92
1.09
0.33
2.47
0.05
0.07
0.01
3.9
56.6
15.2
26.2
Pd(1%)—Cu(1.2%)/SiO2
1.89
0.07

Alkynes hydrogenation of substituted alkynes
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 2, February, 2016
429
α
α
1.0
a
c
1
2
3
1.0
0.8
0.6
0.4
0.2
1
2
3
0.8
0.6
0.4
0.2
100
200
300 τ/min
5
10
15
20 τ/min
α
α
1.0
0.8
0.6
0.4
0.2
b
d
1.0
0.8
0.6
0.4
0.2
1
2
3
1
2
3
100
200
300 τ/min
5
10
15
20 τ/min
Fig. 3. The reaction mixture composition as a function of the DPA hydrogenation time for the monoꢀ and bimetallic catalysts Pd/
Al2O3 (a), Pd—Cu/Al2O3 (b), Pd/SiO2 (c) and Pd—Cu/SiO2 (d): DPA (1), DPE (2), DPET (3); α is mole fraction.
mesured after CO adsorption, the typical bands at 2096
and 1978 cm–1 are observed corresponding to the linear
forms of CO molecules adsorbed on metallic palladium.24—29
The band at 2203 cm–1 corresponds to CO molecules adꢀ
sorbed on the lowꢀcoordinated cations of the support
(Al3+).24,25 After desorption at ~20 °C the bands due to a
bridged form of CO adsorbed on metallic palladium and a
linear form of CO adsorbed on alumina cations disappear.
Moreover, the band of the liner form of CO adsorption
shifts towards lower frequencies resulting from the abꢀ
sence of the dipoleꢀdipole interaction of the nearby adꢀ
sorbed CO molecules («red» shift). The position of the
Pd0—CO singlenton in IR spectra corresponds to 2068
cm–1. An increase in desorption temperature to 100 °С
leads to a complete disappearance of this band.
SDPE
1.0
0.9
0.8
1
2
The spectrum of CO adsorbed on Cu(3%)/Al2O3, inꢀ
cludes a strong asymmetric band with a maximum at
2143 cm–1 corresponding to stretching vibrations of CO
molecule adsorbed on Cu+ cations in linear form.24—31
The asymmetry of this band can be attributed to the presꢀ
ence of different copper sites, such as Cu+ and unreduced
Cu2+, characterized by a small discrepancy in the energy.
Desorption at ~20 °C decreases the intensity while further
desorption at 100 °C removes this band. Only a weak band
at 2126 cm–1 persist. The presence of this band appears to
affect the symmetry of the main band observed after adꢀ
0.7
3
4
0.2
0.4
0.6
0.8
1.0 XDPA
Fig. 4. The dependence of selectivity to DPE formation (SDPE
)
on DPA conversion (XDPA) for the monoꢀ and bimetallic cataꢀ
lysts in the selective DPA hydrogenation: Pd(0.5%)/Al2O3 (1),
Pd(1%)—Cu(1.2%)/Al2O3 (2), Pd(0.5%)/SiO2 (3), Pd(1%)—
Cu(1.2%)/SiO2 (4): P(H2) = 10 bar, T = 25 °C, [DPA] =
= 0.159 mol L–1, mcat = 2.5 mg, solvent is nꢀhexane.

430
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 2, February, 2016
Mashkovsky et al.
A
Pd0—CO
2096
acterize the linear and bridged forms of CO adsorption on
Pd0 correspondingly, remain unchanged after evacuation
at ~20 °C. An increase in the desorption temperature to
100 °С has a slight effect on the position and intensity of
the band at 2065 cm–1. That can be a proof of the formaꢀ
tion of Pd—Cu alloy particles in the bimetallic catalyst.
After the evacuation at 100 °С the intensity of the band at
1980 cm–1 increases considerably with a maximum shiftꢀ
ed to 1965 cm–1. An additional argument in favour of the
formation of bimetallic alloy in the Pd(3%)—Cu(3.6%)
sample can be the change in the ratio between the linear
and bridged CO—Pd0 forms when compared with the
monometallic sample.
a
1
1978
Al3+—CO
2068
2203
2
3
2300
2200
2100
2000
1900
1800 ν/cm–1
Cu+—CO
2143
Thus, we showed that by modifying the catalyst with
copper it is possible to noticeably decrease the reaction
A
b
rate of the second step and increases the ratio rDPA/rDPE
.
1
Some decrease in the activity of the bimetallic catalyst
dramatically increases the selectivity of the target product
of semihydrogenation (DPE) from 85 to 95% at high conꢀ
version of DPA (90—95%). Such behaviour can be exꢀ
plained by the formation of bimetallic Pd—Cu nanopartiꢀ
cles resulted from the reduction of heterobimetallic
PdCu2(AcO)6 complex. Since Pd—Cu alloy is formed, an
amount of Pd active atoms decreases as well as the heat of
semihydrogenated alkene adsorption facilitating its desꢀ
orption and reducing the probability of the ensuing hydroꢀ
genation to alkane. As a result, a decrease in the rate of the
second step of the process and respectively an increase in
the selectivity, are observed.9 The formation of bimetallic
particles was proved by both the FTIRꢀCO and electron
microscopy.
2142
2
3
2126
2300
2200
2100
2000
1900
1800 ν/cm–1
A
Cu+—CO
2140
c
1
Pd0—CO
2065
The authors are grateful to the Department of the
Structure Study of ZIOC RAS (Moscow) for the characꢀ
terization of the samples by electron microscopy and the
International Analytical Centre of ZIOC RAS for the givꢀ
en opportunity to analyse reaction products by CG/MS
technique.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 13ꢀ03ꢀ
121761_ofi_m).
2062
1980
1963
Al3+—CO
2205
2
3
2300 2200
2100
2000
1900 1800 ν/cm–1
Fig. 5. FTIRꢀspectra of СO adsorbed at ~20 °C on the Pd(0.5%)/
Al2O3 (а), Cu(3%)/Al2O3 (b) and Pd(3%)—Cu(3.6%)/Al2O3 (c)
catalysts: adsorption (1), desorption at 25 (2) and at 100 °C (3).
References
sorption of CO because CO molecules are more tightly
bound by Cu+ sites. No bands characterizing CO adsorpꢀ
tion on Cu0ꢀcenters are observed, which gives evidence to
a low stability of the CO—Cu0 complexes.24,25
The IR spectrum of CO adsorbed on Pd(3%)—
Cu(3.6%) includes four adsorption bands. The weak band
at 2205 cm–1, attributable to the carbonyl Al3+—СО comꢀ
plex, completely disappears after removal of the gas phase.
The symmetric band at 2140 cm–1 relates to the stretching
vibrations of CO molecules adsorbed on Cu+ cations. The
following evacuation almost removes this band. The inꢀ
tensities of the bands at 2065 and 1980 cm–1, which charꢀ
1. H. U. Blaser, A. Schnyder, H. Steiner, F. Rossler,
P. Baumeister, in Handbook of Heterogeneous Catalysis,
Eds G. Ertl, H. Knözinger, F. Schüth, J. Weitkamp, Wileyꢀ
VCH Verlag GmbH&Co. KGaA, Weinheim, Germany,
2008, vol. 8, p. 3298.
2. V. P. Ananikov, L. L. Khemchyan, Yu. V. Ivanova, V. I.
Bukhtiyarov, A. M. Sorokin, I. P. Prosvirin, S. Z. Vatsadze,
A. V. Medved´ko, V. N. Nuriev, A. D. Dilman, V. V. Levin,
I. V. Koptyug, K. V. Kovtunov, V. V. Zhivonitko, V. A.
Likholobov, A. V. Romanenko, P. A. Simonov, V. G. Nenajꢀ
denko, O. I. Shmatova, V. M. Muzalevskiy, M. S. Nechaev,
A. F. Asachenko, O. S. Morozov, P. B. Dzhevakov, S. N.

Alkynes hydrogenation of substituted alkynes
Russ.Chem.Bull., Int.Ed., Vol. 65, No. 2, February, 2016
431
Osipov, D. V. Vorobyeva, M. A. Topchiy, M. A. Zotova,
S. A. Ponomarenko, O. V. Borshchev, Yu. N. Luponosov, A. A.
Rempel, A. A. Valeeva, A. Yu. Stakheev, O. V. Turova, I. S.
Mashkovsky, S. V. Sysolyatin, V. V. Malykhin, G. A. Bukhtiꢀ
yarova, A. O. Terent´ev, I. B. Krylov, Russ. Chem. Rev.,
2014, 83, 885.
3. V. P. Ananikov, E. A. Khokhlova, M. P. Egorov, A. M.
Sakharov, S. G. Zlotin, A. V. Kucherov, L. M. Kustov, M. L.
Gening, N. E. Nifantiev, Mendeleev Commun., 2015, 25, 75.
4. A. Borodzinski, G. C. Bond, Catal. Rev., 2006, 48, 91.
5. K. R. Campos, D. Cai, M. Journet, J. J. Kowal, R. D. Larsꢀ
en, P. J. Reider, J. Org. Chem., 2001, 66, 3634.
S. E. Nefedov, Zh. V. Dobrokhotova, V. I. Zhilov, M. N.
Vargaftik, I. I. Moiseev, Catal. Lett., 2006, 112, 155.
17. N. Yu. Kozitsyna, S. E. Nefedov, F. M. Dolgushin, N. V.
Cherkashina, M. N. Vargaftik, I. I. Moiseev, Inorg. Chim.
Acta, 2006, 359, 2072.
18. V. V. Kachala, L. L. Khemchyan, A. S. Kashin, N. V. Orlov,
A. A. Grachev, S. S. Zalesskiy, V. P. Ananikov, Russ. Chem.
Rev., 2013, 82, 648.
19. A. S. Kashin, V. P. Ananikov, Russ. Chem. Bull. (Int. Ed.),
2011, 60, 2602 [Izv. Akad. Nauk, Ser. Khim., 2011, 2551].
20. N. MarinꢀAstorga, G. AlvezꢀManoli, P. Reyes, J. Mol.
Catal. A Chem., 2005, 226, 81.
6. G. C. Bond, in MetalꢀCatalysed Reactions of Hydrocarbons,
Springer Science + Business Media, Inc., New York, 2005,
p. 395.
21. B. M. Choudary, M. Lakshmi Kantam, N. Mahender Redꢀ
dy, K. Koteswara Rao, Y. Haritha, V. Bhaskar, F. Figueras,
A. Tuel, Appl. Catal. A, 1999, 181, 139.
7. N. A. Khan, S. Shaikhutdinov, H.ꢀJ. Freund, Catal. Lett.,
2006, 108, 159.
22. X.ꢀY. Quek, Y. Guan, E. J. M. Hensen, Catal. Today, 2012,
183, 72.
8. A. A. Lamberov, S. R. Egorova, I. R. Il´yasov, Kh. Kh.
Gil´manov, S. V. Trifonov, V. M. Shatilov, Sh. Ziyatdinov,
Kinet. Catal. (Int. Ed.), 2007, 48, 136 [Kinetika i Kataliz,
2007, 48, 143].
23. A. Yu. Stakheev, P. V. Markov, A. S. Taranenko, G. O.
Bragina, G. N. Baeva, O. P. Tkachenko, I. S. Mashkovsky,
A. S. Kashin, Kinet. Catal. (Ind. Ed.), 2015, 56, 733 [Kinetika
i Katal., 2015, 56, 721].
9. I. S. Mashkovskii, O. P. Tkachenko, G. N. Baeva, A. Yu.
Stakheev, Kinet. Catal. (Int. Ed.), 2009, 50, 768 [Kinetika i
Kataliz, 2009, 50, 798].
10. I. S. Mashkovsky, G. N. Baeva, A. Yu. Stakheev, M. N.
Vargaftik, N. Yu. Kozitsyna, I. I. Moiseev, Mendeleev Comꢀ
mun., 2014, 24, 355.
11. T. V. Choudhary, C. Sivadinarayana, A. K. Datye, D. Kuꢀ
mar, D. W. Goodman, Catal. Lett., 2003, 86, 1.
12. A. Yu. Stakheev, B. L. Moroz, I. S. Mashkovsky, P. V. Markꢀ
ov, O. V. Turova, O. P. Tkachenko, P. A. Pyryaev, V. I.
Bukhtiyarov, Russ. Chem. Bull. (Int. Ed.), 2015, 64, 53 [Izv.
Akad. Nauk, Ser. Khim., 2015, 53].
24. A. Davidov, in Molecular Spectroscopy of Oxide Catalyst Surꢀ
faces, Wiley, New York, 2003, 691 pp.
25. K. I. Hadjiivanov, G. N. Vayssilov, Adv. Catal., 2002, 47, 307.
26. S. Sitthisa, T. Pham, T. Prasomsri, T. Sooknoi, R. G. Malꢀ
linson, D. E. Resasco, J. Catal., 2011, 280, 17.
27. B. T. Meshesha, N. Barrabes, J. Llorca, A. Dafinov, F. Meꢀ
dina, K. Föttinger, Appl. Catal. A: General, 2013, 453, 130.
28. P. Benito, M. Gregori, S. Andreoli, G. Fornasari, F. Ospitaꢀ
li, S. Millefanti, M. S. Avila, T. F. Garett, S. Albonetti,
Catal. Today, 2015, 246, 108.
29. M. FernandezꢀGarcia, A. MartinezꢀArias, A. IglesiasꢀJuez,
A. B. Hungria, J. A. Anderson, J. C. Conesa, J. Soria, Appl.
Catal. B: Environmental, 2001, 31, 39.
13. M. P. R. Spee, J. Boersma, M. D. Meijer, M. Q. Slagt,
G. van Koten, J. W. Geus, J.Org. Chem., 2001, 66, 1647.
14. L. Guczi, Z. Schay, Gy. Stefler, L. F. Liotta, G. Deganello,
A. M. Venezia, J. Catal., 1999, 182, 456.
30. A. B. Hungria, A. IglesiasꢀJuez, A. MartinezꢀArias,
M. FernandezꢀGarcia, J. A. Anderson, J. C. Conesa, J. Soꢀ
ria, J. Catal., 2002, 206, 281.
15. P. V. Markov, G. O. Bragina, G. N. Baeva, O. P. Tkachenꢀ
ko, I. S. Mashkovsky, I. A. Yakushev, N. Yu. Kozitsyna,
M. N. Vargaftik, A. Yu. Stakheev, Kinet. Catal. (Int. Ed.),
2015, 56, 591 [Kinetika i Kataliz, 2015, 56, 599].
16. O. P. Tkachenko, A. Yu. Stakheev, L. M. Kustov, I. S. Mashꢀ
kovsky, M. van den Berg, W. Grünert, N. Yu. Kozitsyna,
31. V. Yu. Borovkov, D. R. Luebke, V. I. Kovalchuk, J. L. d´Itri,
J. Phys. Chem. B, 2003, 107, 5568.
Received November 16, 2015;
in revised form November 25, 2015