Environmental Engineering Reference
In-Depth Information
O
V
2
O
5
/TiO
2
Toluene, 363 K
O
O
O
HO
O
Scheme 8.5
Oxidation of 5-Hydroxymethylfurfural with Air over 15% V
2
O
5
/TiO
2
are useful for alcohol oxidation reaction. Hydrated ruthenium oxide is a
stoichiometric oxidant applied for alcohol oxidation reaction such as cin-
namyl alcohol oxidation reaction [123]. h e V
2
O
5
supported on TiO
2
mate-
rial is an active catalyst for the oxidation of 5-(hydroxymethyl) furfural to
2,5-furandicarboxaldehyde (Scheme 8.5) [124].
A broad range of oxides and mixed oxides were tested in the synthesis of
ethyl pyruvate from ethyl lactate [125]. In the case of SnO
2
and ZrO
2
, the
catalyst is highly selective when conversion of ethyl lactate is low, but selec-
tivity of ethyl pyruvate dropped with increased conversion of ethyl lactate.
h e MnO
2
, PdO and dif erent types of binary oxides by addition of Co
2+
,
Fe
3+
and Mn
3+
are ei cient catalysts for dif erent types of alcohol oxidation
reaction. Dif erent types of zeolite, hydrotalcite and phosphate materials
are used as potential catalysts for alcohol oxidation reaction.
Catalytic activity of the supported nanoparticles can also be promoted
by defects in the support material. Defects can trap the metal nanoparticle
and enhance charge transfer between the support and the nanoparticle.
Yo o n
et al.
[126] reported that gold octamers bound to oxygen vacancies
(F centers) on MgO (001) are the smallest clusters to catalyze the low-
temperature oxidation of CO to CO
2
, whereas clusters deposited on close-
to-perfect magnesia surfaces remain chemically inert. It has also been
shown that the surface F centers on MgO play a critical role in the activa-
tion of gold on Au/MgO catalysts [127, 128]. Defects are not the only factor
responsible for charging of the supported metal nanoparticles. Recently,
it was demonstrated that the charge accumulated on the supported gold
nanoparticle can be tuned by varying the thickness of the metal oxide layer
deposited on the metal support [129-133]. h us, the support ef ects can
play an even larger role in gold nanocatalysis than the particle size.
Solid catalysts are widely used for the gas- or vapor-phase oxidation of
simple, small-chain alcohols to the corresponding carbonyl compounds
[117-119]. For gas-phase oxidation of alcohol important requirements
are the reasonable volatility and thermal stability of reactant and products
which strongly limit the synthesis of complex molecules. Solid catalysts
active in the liquid phase under mild conditions have a much broader
application range. A major challenge in liquid-phase oxidation with solid
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