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Chemistry Letters 2000
Selective Oxidation of Ethanol and 1-Propanol over V–Mg–O/TiO Catalyst
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Tharathon Mongkhonsi,* Purida Pimanmas, and Piyasan Praserthdam
Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
(Rceived May 11, 2000; CL-000463)
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Ethanol and 1-propanol can be selectively oxidized to
sium pyrovanadate species (Mg V O ).
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ethanal and propanal, respectively, by V–Mg–O catalyst sup-
The catalytic performance test was performed in a quartz
fixed-bed reactor (6 mm i.d.) packed with 0.3 gram of catalyst
(100–150 mesh). Alcohols (ethanol and 1-propanol) were fed
via a saturator. Pure dry air was used as oxygen source and
nitrogen was used as balancing gas. The feed contained 8 vol%
ported on TiO (anatase). Aldehyde yields up to 73% and 66%
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for ethanal and propanal, respectively, were achieved in the
temperature range 573–623 K. The catalyst was rather inactive
for the further oxidation of aldehyde products to carboxylic
acids.
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alcohol and 5 vol% oxygen, total flow rate 100 mL min . The
reaction was studied in the temperature range 473–773 K.
Combustion products (CO, CO , and H O) were analyzed using
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In the last decade, much attention has been devoted to pro-
duce olefins and oxygenates by direct oxidation of light paraf-
fins. There are three main motivations behind these researches.
The first one in paraffins is less toxic than aromatics. The sec-
ond one is paraffins are cheaper than olefins. And the last one
is the oxidation reaction is thermodynamically more favorable
at lower reaction temperature than dehydrogenation reaction
which requires high temperature. Only few, however, could
achieve industrial application. An example is the replacement
of benzene by butane in maleic anhydride production. The
future of the oxidative dehydrogenation of paraffins to olefins is
still in doubt since a suitable catalyst has yet to be found. The
main problem is the fact that paraffin is rather inactive than its
respective olefin. A catalyst capable to oxidize paraffin is usu-
a gas chromatograph Shimadzu GC 8A equipped with a TCD
and a MS-5A Porapak-Q column. Hydrocarbons were analyzed
using a gas chromatograph Shimadzu GC 14A equipped with a
FID and a VZ-10 column. Oxygenate compounds were ana-
lyzed using a gas chromatograph Shimadzu GC 14B equipped
with a FID and a capillary column. Total carbon balance in
product stream was with in the range 100 ± 5% The selectivity
towards products was calculated from the following expression:
The result obtained from ethanol oxidation is shown in
Figure 1. Between 473–623 K, ethanol conversion rapidly
increased up to a maximum about 86% while selectivity to
ethanal was still higher than 80%. The other observed products
were mainly CO , with traces of CH , C H , and C H . No CO
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ally very reactive for the olefin product formed.
Using an alcohol as reactant is another alternative. C –C
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alcohols can be produced by fermentation of agricultural prod-
ucts. Although the alcohol obtained from fermentation process
has low concentration, the possibility to convert this low con-
centration feed to a more expansive product exists. In this
study the gas phase oxidation process is selected since this
process operates at low reactant concentration to avoid explo-
sive mixture.
appeared in the product stream. The maximum ethanal yield,
73%, occurred at 623 K. Beyond 623 K, both ethanol conver-
sion and ethanal selectivity slightly decreased.
V–Mg–O catalyst system has found some limited success
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in the oxidative dehydrogenation reaction. To the best of our
knowledge, there is no published information about supported
V–Mg–O catalyst. V O has been known to have strong inter-
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action with MgO and TiO (anatase). Therefore, in our research
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we experimentally supported V–Mg–O on TiO (anatase) and
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applied this new catalyst system to the gas phase oxidation of
alcohols.
The catalyst studied 9V2MgTi (8.7 wt% V O , 2 wt% Mg,
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surface area, BET method, 9.27 m g ) was prepared by wet
impregnation method. TiO was added to an aqueous solution
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of NH VO and dried at 353 K until achieving a thick paste.
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The obtained paste was calcined in air at 823 K for 6 h to con-
vert the paste into V O /TiO . Then, Mg was introduced into
1-Propanol conversion and product selectivities are shown
in Figure 2. The conversion of 1-propanol increased rapidly
between 473–573 K, reaching a maximum conversion about
85%. Beyond 573 K, the conversion was quite constant. The
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V O /TiO by impregnation from Mg(NO ) solution. The sus-
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pension was dried and calcined again at the conditions men-
tioned above. The XRD pattern of the obtained 9V2MgTi cata-
main products observed were propanal and CO . Methanal,
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lyst showed only the peaks of TiO (anatase). Surface analysis
CH , C H , and C H also appeared in the product stream. No
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by FT-IR spectroscopy showed three IR absorption bands
around 976, 920 and 878 cm which can be assigned to magne-
CO could be detected in the product stream. The maximum
propanal yield (about 66%) was achieved at 573 K.
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Copyright © 2000 The Chemical Society of Japan
Mongkhonsi, Tharathon
