Chemistry Reference
In-Depth Information
d
n
4
r
4
n
g
|
0
Figure 3.14 Parts (a) and (b) show the reaction mixture and the response of
Ru(OH)
x
/Fe
3
O
4
to a magnet, respectively.
.
Figure 3.15 TEM image of RuHAP-g-Fe
2
O
3
and STEM elemental mappings.
Kaneda and co-workers developed magnetic g-Fe
2
O
3
-containing ru-
thenium hydroxyapatite (Ru/HAP-g-Fe
2
O
3
), which was found to be an
effective catalyst for the oxidation of alcohols under atmospheric pressure of
molecular O
2
.
111
g-Fe
2
O
3
nanocrystallites were dispersed in the HAP matrix
and a monomeric ruthenium cation exists uniformly on the outer surface
(Figure 3.15). The oxidation state of ruthenium on HAP-g-Fe
2
O
3
was found
to be
þ
4, which is different from that in Ru/HAP (
þ
3). The activity of Ru/
HAP-g-Fe
2
O
3
was dramatically improved over Ru/HAP and the former was
found to be applicable to various alcohols, including allylic, benzylic,
aliphatic and heterocyclic alcohols. Compared with Ru/HAP (TOF 2 h
1
)
and RuCo/HAP (TOF 78 h
1
), Ru/HAP-g-Fe
2
O
3
showed a higher catalytic
performance (TOF 196 h
1
).
The activities of various heterogeneous ruthenium catalysts for the aerobic
oxidation of benzyl alcohol to benzaldehyde are summarized in Table 3.2.
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