E.M. Sulman et al. / Journal of Catalysis 262 (2009) 150–158
157
Table 6
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Catalyst
Pd content, wt%
Selectivity, %
Activity,
−1
mol LN mol Pd−1 s
Run 2a
Run 5
Run 2
Run 5
Run 2
Run 5
PS-b-P4VP–Pd/Al2O3
PS-b-P4VP–PdAu/Al2O3
PS-b-P4VP–PdPt/Al2O3
PS-b-P4VP–PdZn/Al2O3
0.02
0.02
0.03
0.04
0.02
0.02
0.03
0.04
98.5
99.0
98.0
98.5
99.0
98.0
98.0
99.0
57.9
27.0
23.1
58.7
27.2
23.5
128.3
131.4
a
Run 1 is shown in Table 5.
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4. Conclusions
In this paper we demonstrated that deposition of NP containing
micellar catalysts on alumina causes no changes in the NP mor-
phology, but leads to different catalytic behavior depending on the
NP structure. In the absence of the acceptor metal-modifier (for
Pd and PdZn NPs), the key modifying factor is the increase of the
polarity of the system upon heterogenization. This leads to the in-
crease of the amount of catalytic sites and to the increase of the
catalytic activity. When a metal-modifier is the acceptor (for PdAu
and PdPt NPs), this leads to the electron deficiency of the surface
Pd atoms and most likely their stronger adsorption on alumina,
thus impeding access to some catalytic centers. This also results in
the emergence of an induction period, the length of which is con-
sistent with the acceptor ability of a modifying metal. Comparison
of the catalysts studied in this work with the commercial Pd/Al2O3
shows that the activity of the heterogenized micellar catalysts con-
taining mono- and bimetallic nanoparticles is much higher than
that of the commercial catalyst owing to lower activation energy
and/or higher amount of catalytic sites.
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This work has been supported, in part, by the NATO Science for
Peace Program (grant SfP-981438) and, in part, by Russian Founda-
tion for Basic Research (grant 04-03-32928-a). We also thank Prof.
Dr. M. Antonietti for the PS-b-P4VP sample and Dr. J. Hartmann for
the TEM images of micellar samples.
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