Palladium supported on detonation nanodiamond as a highly effective catalyst of the C=C and C≡C bond hydrogenation

Article abstract of DOI:10.1016/j.catcom.2010.12.001

Palladium loaded on detonation nanodiamond was used for the first time as a catalyst for the C=C and C≡ C bond hydrogenation. By the example of tolane hydrogenation, the Pd(0)/nanodiamond was found to greatly surpass in catalytic activity other Pd(0)/nanocarbon catalysts.

Full text of DOI:10.1016/j.catcom.2010.12.001

Catalysis Communications 12 (2011) 577–579
Contents lists available at ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Palladium supported on detonation nanodiamond as a highly effective catalyst of the
C=C and C≡C bond hydrogenation
b
Olga V. Turova a, Eugenia V. Starodubtseva a, Maxim G. Vinogradov a, , Viacheslav I. Sokolov ,
⁎
Natalya V. Abramova b, Alexander Ya. Vul' c, Alexander E. Alexenskiy c
a
N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov St., 119991 Moscow, Russian Federation
Ioffe Physical-Technical Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya ul., 194021 St. Petersburg, Russian Federation
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 28 June 2010
Received in revised form 22 November 2010
Accepted 1 December 2010
Available online 13 December 2010
Palladium loaded on detonation nanodiamond was used for the first time as a catalyst for the C=C and C≡C
bond hydrogenation. By the example of tolane hydrogenation, the Pd(0)/nanodiamond was found to greatly
surpass in catalytic activity other Pd(0)/nanocarbon catalysts.
© 2010 Elsevier B.V. All rights reserved.
Keywords:
Palladium catalyst
Detonation nanodiamond
C=C and acetylenic bond hydrogenation
1. Introduction
In connection with the foregoing, DND is of particular interest as a
non-traditional carrier for the preparation of metal-containing cat-
One of the trends in modern heterogeneous catalysis is the fixation
of a catalytic active centre (often metal) on a neutral carrier. The metal
atom may be surrounded by ligands, assisting in realization of catalytic
function. Due to the production of different forms of nanocarbon [1], it
became possible to combine functions of a ligand and a carrier. Pre-
viously, we have studied the catalytic action of the individual palladi-
um complexes of fullerenes C60 and C70 [2] as well as that of palladium
clusters immobilized on carbon nanotubes (CNT) [3] in the hydroge-
nation of the triple bond of diphenylacetylene (tolane) and found
that, in the latter case, the palladium catalyst is much more active. An
advantage of non-molecular forms of nanocarbon as metal carriers
(it relates, primarily, to the carbon nanotubes) is that they can form
π-olefinic bonds with the metal atoms in the absence of other ligands,
which may slow down the reaction as do, for example, tertiary
phosphines in the fullerene complexes (η2-C60)Pd(PR3)2 [2].
In the last few years, increasing attention has been given to such
form of non-molecular carbon as detonation nanodiamond (DND),
which is prepared by the explosion method from polynitro compounds
[4–10]. DND as a support for metal clusters differs from fullerenes and
nanotubes because it has no genuine double bonds capable of forming
π-complexes with the supported metals. Therefore, nanodiamond is to
be bound to metals in another way, for example, through the sp2-
hybridized carbon atoms or sp3 atoms with an uncompensated valency
being involved into the shell of the nanodiamond particles [6,7].
alysts and for the investigation of their catalytic activity in different
chemical reactions involving hydrogenation. However, information in
the literature regarding the use of nanodiamond in heterogeneous
catalysis is scarce. Thus, few catalysts supported on nanodiamond and
containing Pt [11], Pd [12], Ni [13,14], Fe [15], and Cu [16] have been
described. They were used, correspondingly, for the oxidation of CO,
the hydrodechlorination of polychloroaromatic hydrocarbons, the hy-
drogenation of toluene to methylcyclohexane or methanol to methane
as well as for the decomposition of some inorganic substances and
organic nitro compounds.
In this work, we describe the preparation of the catalyst Pd(0)/DND
and its use in the hydrogenation of multiple carbon–carbon bonds of
different types. Tolane (1), α-phenylcinnamic acid (4), and enamides 6
and 8 were selected as model substrates (Scheme 1). To the best of our
knowledge, this is the first report on the liquid-phase hydrogenation of
unsaturated organic compounds with participation of the Pd/DND
catalyst.
2. Experimental
2.1. General
Tolane (1) and α-phenylcinnamic acid (4) are commercial (Acros)
reagents used without additional purification. Enamides 6 [17] and
8 [18] were prepared according to the known procedures. Prior to use,
MeOH was dehydrated and distilled under a flow of argon. Argon was
purified by passing through columns containing a nickel–chromium
⁎
Corresponding author. Fax: +7 495 135 5328.
E-mail address: ving@ioc.ac.ru (M.G. Vinogradov).
1566-7367/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.catcom.2010.12.001

578
O.V. Turova et al. / Catalysis Communications 12 (2011) 577–579
PhCH2CH2Ph
Ph
Ph
+
Ph
Ph
2
3
1
PhCH=C(Ph)COOH
PhCH2CH(Ph)COOH
5
H2
4
PhCH(NHAc)CH3
PhC(NHAc)=CH2
7
6
PhCH2CH(NHAc)COOMe
PhCH=C(NHAc)COOMe
8
9
Scheme 1. Hydrogenation of the C=C and C≡C bonds on the Pd/DND catalyst.
catalyst, copper supported on Kieselguhr (80 °C), and molecular sieves
(4 Å). Hydrogen was purified by passing through columns with a
nickel–chromium catalyst and molecular sieves. The conversion of the
substrate and the composition of hydrogenation products were
determined by the 1H NMR method on a Bruker AM-300 instrument.
[3]. A representative elemental analysis of the prepared catalyst
showed (found %: C 88.11, H 0.79, N 2.31, and Pd 1.99) that the carbon
content in the catalyst was about 90%, whereas the remaining mass
accounted, obviously, for different O- and N-containing functional
groups bound to the cores of DND particles. The maximum size of the
supported palladium clusters determined by the transmission electron
microscopy was found to be 6 nm.
2.2. Preparation of the catalyst Pd/DND
To prepare the Pd/DND catalyst, samples of DND were obtained by
standard procedure [19] through the detonation of a trinitrotoluene/
hexogen mixture (60/40) followed by the purification with 50% nitric
acid in an autoclave at a temperature of about 200 °C under a pressure
of 100 atm. The specific surface area and the mean pore size of the
DND powder were found to be approximately 350 m2/g and 10 nm
respectively, the average size of the diamond crystallites being not
more than 4 nm. The latter, in turn, was transformed into porous but
hard aggregates in sizes about 150 nm each having a fractal struc-
ture [19]. To remove residual admixtures consisting mainly of iron
oxides (∽1%), the technical product was in additional purified by the
treatment with 40% HCl at ultrasonication [20]. The washing with HCl
was performed several times until the yellow–brown colour of the
liquid disappeared, and the test for rhodanide was negative. Finally,
the DND powder was washed with deionized water until a stable
hydrosol formed. The dried hydrosol was analyzed by the EPR method
[21]. The absence of the signal at g≅4 in the EPR spectra serves as the
criterion for the removal of iron from DND samples.
2.3. Catalytic hydrogenation
In a typical experiment, tolane (1) (168 mg, 0.94 mmol) and the
catalyst Pd(2%)/DND (1 mg, 0.19 μmol) were placed into a glass tube
for hydrogenation. Then the tube was evacuated, filled with argon and,
after the addition of a solvent (MeOH) (3 ml), was transferred to a steel
autoclave (50 ml). The latter was blown through with hydrogen and
pressured to 20 atm of H2. Hydrogenation was carried out under the
conditions given in Tables 1 and 2 with magnetic stirring (700 ppm) of
the reaction mixture. The further increase of this value up to 1200 ppm
in the test runs did not change the reaction rate. This result testifies
that, at the used conditions, the reaction fulfills the kinetic control (not
mass-transport limited). The resulting suspension was filtered, then
the solvent was removed, and the products were analyzed by the 1H
NMR method.
3. Results and discussion
The DND powder thus obtained was applied as a support for pal-
ladium (2%) using a benzene solution of the complex Pd2(dba)3 (dba —
dibenzylideneacetone) as a source of zero-valent metal. The procedure
was similar to that used for preparation of the catalyst Pd(0)/nanotubes
The results of our work are summarized in Tables 1 and 2. We
showed that palladium supported on DND has a high catalytic activity
in the hydrogenation of all selected unsaturated compounds. At the
same time, as it follows from the found turnover number (TON)
Table 1
Hydrogenation of tolane (1) catalyzed by Pd(2%)/DNDa.
Entry
1/Pd, mol/mol
Hydrogenation conditions
Conversion (%)
Reaction products (% mol)
T/°C
τ/h
2
3
1
5000
5000
5000
50
50
20
20
20
50
50
50
2
2
2
2
2
2
1
5
100
100
100
–
–
–
100
100
96
2b
3
4
c
4
–
–
–
–
–
5d
6
5000
10,000
10,000
50,000
–
100
100
72e
100
N99
32
7
8
b1
68
a
0.5–1.0 mg of Pd/DND, 20 atm (H2), and abs. MeOH (3 ml) were used.
The catalyst isolated from the reaction mixture (entry 1) was re-applied.
The DND sample without supported palladium was used, and unconverted 1 was only isolated.
No hydrogenation with Pd(5%)/C (Acros) took place under the pointed conditions [3].
The TON value (products/catalyst/reaction time) was 7200 h−1 for this experiment.
b
c
d
e

O.V. Turova et al. / Catalysis Communications 12 (2011) 577–579
579
Table 2
natural diamond surface contains regions of the partially olefinic
character [22]. This may promote the formation of Pd–C σ-bonds.
Furthermore, the oxygen atoms of functional groups such as OH or COOH
connected with a shell of the DND cores [6,7] may participate in the
formation of σ-bonds with palladium as well.
Catalytic hydrogenation on Pd(2%)/DND of the C=C bond-containing substrates 4, 6,
and 8 to give compounds 5, 7, and 9 respectivelya.
Entry
Substrate (S)
[S]/[Pd]
Conversion (%)
TON
(h−1
)
1
2
3
4
5
6
4
4
6
6
8
8
1000
5000
1000
5000
1000
5000
100
25
100
32
100
24
–
250
–
4. Conclusions
320
–
Using DND as a carrier to prepare the palladium catalyst, the hy-
drogenation of the C=C and C≡C bonds of model organic compounds
(tolane, unsaturated acid and enamides) was performed for the first
time. The activity of the Pd(0)/DND was found to greatly surpass that of
palladium loaded on other nanocarbon supports (fullerenes and carbon
nanotubes) asit wasshown by theexampleofthe tolanehydrogenation.
The highest catalytic activity of the Pd(0)/DND may be apparently
attributed to the unusual attachment of the palladium clusters to the
nanodiamond surface modified in the course of the DND synthesis by
the explosion method.
240
a
1 mg of Pd(2%)/DND, 20 atm(H2), abs. MeOH (3 ml), and 50 °C, 5 h.
values, the reactivity of acetylenic substrate 1 in the Pd/DND catalyzed
hydrogenation proved to be more than one order higher compared
with TON magnitudes for ethylenic substrates 4, 6 and 8 (respectively,
7200 and 250–300 h−1) under the same reaction conditions (Table 1,
entry 8; Table 2, entries 2, 4, and 6). With all these going on, as the
results of control experiments showed, the TON values for the Pd/DND
catalyst proved to be independent of the S/Pd variations. An important
point is also that the catalyst isolated from the reaction mixture (Table 1,
entry 1) maintains the high activity being used repeatedly in the same
reaction (entry 2).
It is of interest to compare the catalytic activity of palladium
supported on different carbon materials, the hydrogenation of tolane
being the best appropriate thereto. Thus, the TON values in this reaction
carried out in MeOH were as follows: 6 for the catalyst (η2-C70)Pd
(PPh3)2 at 50 °C [2] and 2500 for Pd(0) supported on carbon nanotubes
at 60 °C [3]. These values are much below than those for the catalyst Pd
(0)/DND (Table 1, entry 8). At the same time, comparison of the TON
values for different Pd/nanocarboncatalysts allows only an approximate
evaluation of their activity. Thus, the activity of Pd/DND such evaluated
may be, in fact, much higher than that of Pd/CNT, taking into account
that the latter used in the same reaction had the greater specific surface
area of the carrier (600–700 m2/g) [3] than Pd/DND (~350 m2/g).
Parallel with the TON values, such factor as selectivity of the tolane
hydrogenation can be also considered to evaluate the palladium catalyst
activity. As evident from Table 1, the reaction catalyzed by Pd/DND at
20 °C for 2 h gives only 4% of stilbene and 96% of diphenylethane (entry
3), whereasolefin 2 is thepredominantproduct (75%) in the caseif a less
active Pd/CNT catalyst was used at the same conditions [3].
References
[1] A.Ya. Vul', V.I. Sokolov, Nanotechnol. Russ.
4 (2009) 3978 (Translated from
Rossiiskie Nanotekhnologii 2 (2007) 17–30).
[2] E.V. Starodubtseva, V.I. Sokolov, V.V. Bashilov, Y.N. Novikov, E.V. Martynova, M.G.
Vinogradov, O.V. Turova, Mendeleev Commun. 18 (2008) 209–210.
[3] E.V. Starodubtseva, M.G. Vinogradov, O.V. Turova, N.A. Bumagin, E.G. Rakov, V.I.
Sokolov, Catal. Commun. 10 (2009) 1441–1442.
[4] A.Ya. Vul', A.E. Aleksenskiy, A.T. Dideykin, Detonation nanodiamonds: technology,
properties and applications, in: V.N. Kharkin, Ch. Bai, S.-C. Kim (Eds.),
Nanosciences and Nanotechnologies, Encyclopedia of Life Support Systems
(EOLSS), Developed under the Auspices of the UNESCO, EOLSS Publishers, Oxford,
UK, ISBN: 978-92-3-403999-4, 2009. http://www.eolss.net, (UNESCO).
[5] A. Aleksenskiy, M. Baidakova, V. Osipov, A. Vul', The fundamental properties and
characteristics of nanodiamonds, in: Dean Ho (Ed.), 1 edition, Nanodiamonds:
Applications in Biology and Nanoscale Medicine, Springer, New York, ISBN:
1441905308, 2009, pp. 55–788, 978-1-4419-0530-7.
[6] S. Osswald, G. Yushin, V. Mochalin, S.O. Kucheyev, Y. Gogotsy, J. Am. Chem. Soc.
128 (2006) 11635–11642.
[7] Q. Zou, Y.G. Li, L.H. Zou, M.Z. Wang, Mater. Charact. 60 (2009) 1257–1262.
[8] A.M. Panich1, A.I. Shames, H.-M. Vieth, E. Osawa, M. Takahashi, A.Ya. Vul', Eur.
Phys. J. B 52 (2006) 397–402.
[9] M. Dubois, K. Guérin, E. Petit, N. Batisse, A. Hamwi, N. Komatsu, J. Giraudet, P.
Pirotte, F. Masin, J. Phys. Chem. 113 (2009) 10371–10378.
[10] X.W. Fang, J.D. Mao, T.M. Levin, K. Schmidt-Rohr, J. Am. Chem. Soc. 131 (2009)
1426–1435.
[11] N.N. Vershinin, V.A. Bakaev, O.N. Efimov, I.I. Korobov, A.L. Gusev, A.E. Alexenskii,
M.V. Baidakova, A.Ya. Vul', Alternativnaya Energetika
123–1278 (Russia).
i Ekologiya 9 (2009)
A great difference in the activity of the palladium catalysts on the basis
of fullerenes, nanotubes and DND may be explained by structural features
of these carbon materials. Investigation of the DND structure by modern
physicochemical methods [4–10] including solid-state NMR [8–10]
showed that the purification of technical DND by conventional oxidation
methods is unsuitable for the entire removal of impurities of fullerene- or
graphite-like conglomerates, which form a thin shell on the surface of
DND cores. However, this fact would play a positive role if DND is used as
a support for the preparation of the metal-containing catalysts. As would
be expected, the sp2-carbon centres of such surface fragments enable
more strong coordination of metal clusters, including palladium clusters,
compared to the non-modified surface containing only sp3-carbon
centres. At the same time, the formation of σ-bonds between palladium
and the surface sp3-carbon atoms cannot be ruled out. As it was shown
under ultrahigh vacuum (UHV) conditions (10−10 Torr), even the
[12] (a) S.A. Kachevskii, E.V. Golubina, E.S. Lokteva, V.V. Lunin, Russian J. Phys. Chem.
81 (2007) 866–8738 (Translated from Zhurnal Fizicheskoi Khimii 81 (2007)
998–1005);
(b) E.V. Golubina, S.A. Kachevsky, E.S. Lokteva, V.V. Lunin, P. Canton, P. Tundo,
Mendeleev Commun. 19 (2009) 133–135.
[13] I. Kolev, S. Stavrev, Ch. Minchev, Appl. Surf. Sci. 253 (2007) 7115–7123.
[14] V. Mavrodinova, M. Popova, D. Mitev, S. Stavrev, S. Vassilev, Ch. Minchev, Catal.
Commun. 8 (2007) 1502–1506.
[15] T. Tsoncheva, M. Dimitrov, L. Ivanova, D. Paneva, D. Mitev, B. Tsintsarski, I. Mitov,
S. Stavrev, Ch. Minchev, J. Colloid Interface Sci. 300 (2006) 183–189.
[16] X.Q. Shi, H. Hong, L.D. Lu, X.J. Yang, H. Wang, Mater. Lett. 62 (2008) 1238–1241.
[17] M.J. Burk, G. Casy, N.B. Johnson, J. Org. Chem. 63 (1998) 6084–6085.
[18] B.D. Vineyard, W.S. Knowles, M.J. Sabacky, G.L. Bachman, D.J. Weinkauff, J. Am.
Chem. Soc. 99 (1977) 5946–5952.
[19] M. Baidakova, A. Vul', J. Phys. D Appl. Phys. 40 (2007) 6300.
[20] A.E. Alexenskii, A.Ya. Vul', M.A. Yagovkina, Russian Pat. 2322389 (20.04.2008).
[21] A.E. Alexenskii M. Baidakova, A.I. Veigner, A.Ya. Vul', S.P. Vul', M.A. Yagovkina,
Russian Pat. No 2388688 (10.05.2010).
[22] J.M. Buriak, Angew. Chem. Int. Ed. 40 (2001) 532–534.