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Journal of Materials Chemistry A
Page 10 of 12
ARTICLE
Journal Name
additional catalytically active surface Pd(0) species in the sample.12
This possible reduction could be relatively insignificant in for
catalysts 2 and 3 because these two produced much less amount of
H2 compared with that produced by catalyst 1. In other words, most
of the possible PdO species present on the former two catalysts
remained more likely in oxidized forms even after FA
dehydrogenation reaction. Notably also, although TEM analysis of
the spent-catalysts indicated that the average sizes of Pd NPs
increased slightly after the 3rd cycle in all cases (for 1, from 1.5 nm
to 2.3 nm; for 2, from 1.6 nm to 2.1 nm; and for 3, from 2.9 nm to
4.4 nm) (see Figure S6), the catalysts largely retained their activity,
and even became more active in some cases, for the reaction.
The slight increase in the size of Pd NPs after recycling can be
explained based on the weakened interaction between the Pd NPs
and the grafted organoamine functional groups during the
reactions. Given the fact that the adsorbed formic acid molecules
undergo deprotonation with grafted organoamine groups (via Pd-
under grant no.: 2015M1A2A2074688.
DOI: 10.1039/C7TA02040F
Notes and references
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+
HCOOH…NR2-SBA-15 Pd-HCOO- + NHR2 -SBA15; please also see
Step 1 in Scheme 2), the resulting SBA-15-supported quaternary
+
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Conclusions
In conclusion, we have successfully synthesized and characterized
the structures, compositions and catalytic properties for FA
dehydrogenation of
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a series of Pd/SBA-15-Amine materials
containing different types of amine groups and Pd NPs. Using the
results, the relationships between amine groups and the Pd NPs
forming in the materials have been investigated. The catalytic
activity of the materials have been found to directly and indirectly
relate to the terminal amine functional groups present in the
materials. Specifically, the types of amine functional groups are
found to dictate the size of the Pd NPs forming in the materials, the
electronic properties in the materials, and the pore diameters and
pore volumes in the materials. These have, in turn, dictated the
overall degree of catalytic activities of the materials toward FA
dehydrogenation. The structural and composition parameters
identified for the materials in relation to their catalytic properties
toward FA dehydrogenation reaction here may provide valuable
guidelines for the development of other efficient catalysts to
generate H2 on-board for H2-powered fuel cells.
Acknowledgements
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T.A. gratefully acknowledges the finanicial support of the
National Science Foundation (NSF) in the US under grant no.:
DMR-1508611. C.W.Y. acknowledges the financial support
from the Technology Development Program to Solve Climate
Changes of the National Research Foundation (NRF) funded by
10 | J. Name., 2012, 00, 1-3
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