Partial oxidation of ethanol over cobalt oxide based cordierite monolith catalyst
Clarissa Perdomo Rodrigues, Victor Teixeira da Silva, Martin Schmal
NUCAT/PEQ/COPPE, Federal University of Rio de Janeiro, C.P. 68502, 21945-970, Rio de Janeiro, Brazil
During the 1990s, there was an increasing interest in producing
cheaper synthetic fuels, and the catalytic partial oxidation became
widely studied in the industries and academic research groups [1–
7]. In most laboratory research, the partial oxidation studies were
done in ﬁxed bed microreactors. These reactors present dis-
advantages such as sintering, pressure drop and preferential path
toward the bed.
A promising alternative to eliminate the disadvantages of ﬁxed
bed reactor is the monolithic reactor . The advantage in
developing processes using monolith-based reactors is the
extremely low contact time (in the order of milliseconds). Oleﬁns
production via catalytic oxidative dehydrogenation of light
parafﬁn and hydrogen production via catalytic partial oxidation
of hydrocarbons are the most important processes for which
applications of monolithic catalysts have been evaluated .
In general, the temperature for partial oxidation is extremely
high at very low contact time that corresponds to space velocities
range from 2 to 1 Â 10
where different products are involved
and different mechanistic conclusions are drawn [10–13].
Besides, the literature [11,14] shows that at higher tempera-
tures and space velocities the surface and gas ﬁlm reactions are
favored, resulting in a mass transfer limited process inside the
individual monolith passages. An alternative to minimize the
effects of mass transfer is to use catalysts preparation methodolo-
gies that reduce the cross-sectional area in contact with reagent
ﬂow and concentrate the active sites of the catalyst on the surface
of the monolith channel. In this case, the washcoating method in
two stages showed evidences that it is the best option to minimize
the cross-sectional area of monolith channels . Another
alternative is to improve the operating conditions in order to
promote the formation of H
and inhibit the effects of mass transfer
in gas phase.
Although the catalytic partial oxidation process to produce
hydrogen has never been used commercially, it is the most
promising because it offers advantages as low operation tempera-
tures and low formation of soot or secondary products. Another
important aspect of the partial oxidation is the space velocity at
which the reactors operate, that is able to provide a negligible
pressure drop in the packed bed reactor. According to Hohn and
Schmidt  studies on the methane partial oxidation showed that
the use of high space velocity results in a decrease of conversion
and selectivity. Therefore, the oxidation of light hydrocarbons on
monolithic reactors with low contact time has been intensively
studied, showing satisfactory results with regard to conversion,
selectivity to synthesis gas, operating conditions, no formation of
carbon and reactor dimensions.
The literature is very scarce on information about the partial
oxidation of ethanol. However, some authors [10–14] have
reported that it is possible to produce hydrogen directly from
ethanol by the reaction shown in Eq. (1). The subscripts s and g in
the Eq. (1) mean respectively steam and gas phase. This reaction
can be seen as a promising procedure to produce hydrogen because
it offers advantages as rapid ignition and size of reactor. In this
case, the reactor used is more compact than the system required to
Applied Catalysis B: Environmental 96 (2010) 1–9
Received 1 September 2009
Received in revised form 20 January 2010
Accepted 26 January 2010
Available online 2 February 2010
Ethanol partial oxidation
Ethanol partial oxidation was studied on Co
/cordierite honeycomb structured catalyst.
Honeycomb structure consists of parallel channels that favor the gas phase reactions, which in some
temperature and ﬂow rate conditions could be limited by mass transfer effects in gas phase. The catalytic
activity and products selectivity were evaluated at different temperatures and O
:ethanol ratios. Also, it
evaluated the effect of space velocity (h
) and presence of H
O in the feed. Overall, the results showed
that the partial oxidation reaction occurs in a way that the ethanol is ﬁrst decomposed in gas phase and
then formed in the presence of oxygen radicals that decomposed on the catalyst surface. The CO
ratio observed in most experiments indicates that shift reaction occurs in gas phase and its equilibrium
limits the hydrogen formation. Although this catalyst has not presented any signiﬁcant deactivation,
some carbon formation was observed after 30 h on reaction.
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* Corresponding author. Tel.: +5521 2562 8352; fax: +5521 2562 8300.
E-mail address: email@example.com (M. Schmal).
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