988
Z. Karimi, A.R. Mahjoub / Catalysis Communications 12 (2011) 984–988
Fig. 4. Catalysts' reusability assessment for oxidation of BSB.
[
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using atomic absorption analysis. 0.31 mg tungsten is shown to be
present in the filtrate which confirms the hypothesis of leaching in
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[
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4
. Conclusion
[
1
Inorganic–organic hybrids are designed by inclusion of
[
[
K
6
P
2
W
18
O
62 Dawson and K14[NaP
5
W
30
O
110] Preyssler salts within
+
MCM-48, SBA-3, SBA-15 and NH
3
functionalized mesoporous silicas.
3
The newly designed heterogeneous systems are shown to combine
catalytic activity of POM with high surface area of mesoporous sup-
ports. Such kind of materials can be efficiently used as environmen-
tally benign and selective heterogeneous catalysts for oxidation of
thioethers to sulfoxides. The Preyssler complex is found to be a more
active catalyst compared to its Dawson analog. The size of pores and
functional groups present on the surface and within the pores and
channels of the silica support is shown to be a determining factor for
oxidation efficiency, stability, and reusability of the catalysts. Catalysts
[
[
[
[
[
[
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with larger pores are proven to be better catalysts for oxidation of
+
relatively large thioethers. NH
3
functional group is shown to improve
10409.
the sorption properties of the support and elevate the catalyst's
activity and stability. Reusability investigations indicate that all the
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[
[
[
newly designed systems are heterogeneous and reusable. However,
+
[
SBA-15-NH
3
]/P
5
is proved to be the superior heterogeneous catalyst
for oxidation of thioethers, which may be recovered at least for 4 runs
without any significant loss in activity. Heterogeneity of the newly
designed catalysts is also studied. The systems are shown to be heter-
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7
Acknowledgment
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Financial support of this work by Tarbiat Modares University and
Iran National Science Foundation (INSF) is gratefully acknowledged.
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