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PAPER
Synthesis of Pd/SBA-15 catalyst employing surface-
bonded vinyl as a reductant and its application in
the hydrogenation of nitroarenes†
Cite this: RSC Adv., 2017, 7, 3443
Ying Duan,ab Min Zheng,a Dongmi Li,a Dongsheng Deng,a Cuicui Wua
a
*
and Yanliang Yang
The Pd/SBA-15 catalyst was synthesised through the reduction of PdCl2 by the surface-bonded vinyl group
on vinyl-functionalized SBA-15, which was prepared via co-polymerization. XRD and XPS characterization
confirmed the successful reduction of Pd(II) to Pd(0). Pd/SBA-15 showed a narrow palladium particle-size
distribution of about 5–6 nm in the TEM image. The Pd/SBA-15 catalyst was effective for the
hydrogenation of aromatic nitro compounds with zero-order kinetics, and the TOF for the
hydrogenation of nitrobenzene was 1124 hꢀ1 at 313 K and 1 atm H2. A steric effect was observed for the
substituted nitroarenes.
Received 15th November 2016
Accepted 16th December 2016
DOI: 10.1039/c6ra26811k
homogeneously distributed Pd crystals was obtained. Li et al.
rst synthesized a Si–H functionalized phenyl-bridged periodic
mesoporous organosilica (PMO).26 Then, Pd nanoparticles were
immobilized onto the PMO by a Si–H in situ reduction method.
The resulting catalysts showed excellent catalytic activity and
selectivity for the Ullmann reaction in water.
Anilines, which are important chemical raw materials, are
widely applied for the synthesis of dyes, agrochemicals, poly-
mers, pharmaceuticals, and other ne chemicals.27,28 The
conventional procedure for the production of aromatic amines
is the reduction of the corresponding nitro derivatives. There-
fore, it is highly signicant to synthesize an appropriate catalyst
with remarkable performance for this hydrogenation
procedure.29–32
In this study, we report the preparation of SBA-15 with
surface-bonded vinyl as a catalyst. Also, vinyl was used as
a reducing agent for the synthesis of Pd/SBA-15. As illustrated in
Scheme 1, PdCl2 was reduced by the surface-bonded vinyl group
to afford Pd(0), which is part of the Wacker reaction. Once vinyl
is consumed, the palladium nanoparticles cannot grow bigger.
Introduction
Owning to their unique structures and high activity, the
synthesis of supported palladium nanoparticles is of great
signicance in heterogeneous catalysis.1–3 Numerous methods
have been developed to prepare these catalysts, which have
been widely used in hydrogenation,4–8 hydrogenolysis,9–12
decarbonylation,13,14 coupling reactions,15–18 oxidation,19 and so
on.20–23 The synthesis of supported palladium nanoparticles
usually involves a palladium salt as the palladium source to be
reduced to palladium(0) by a reducing agent, such as H2, formic
acid or glycol. Since the palladium salt and the reducing agent
do not oen symmetrically distribute on the supports, addi-
tional means should be taken to acquire a uniform distribution
of the palladium nanoparticles. For example, PVP is usually
used as
a protective agent to stabilize the palladium
nanoparticles.24
An interesting method for the preparation of supported
palladium nanoparticles is to employ
a reducing agent
uniformly bound to the surface of the supports. The palladium
salt then could only be reduced on the surface of the supports
and the resulting palladium nanoparticles will not enlarge as
there are no more reducing agents nearby. Lu's group reported
an example of the preparation of carbon spheres supported
palladium using the surface groups as reducing agents.25
A
superior product with small (d ¼ 7.66 nm, s ¼ 1.94 nm),
aHenan Key Laboratory of Function-Oriented Porous Material, College of Chemistry
and Chemical Engineering, Luoyang Normal University, Luoyang 471934, P. R.
China. E-mail: yangyl0410@126.com
bCollege of Food and Drug, Luoyang Normal University, Luoyang 471934, China
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c6ra26811k
Scheme 1 The preparation of Pd/SBA-15 using surface-bonded vinyl
as reductant.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 3443–3449 | 3443