Mixed Matrix Vanadium Oxide Catalytic Nanocomposite Membrane For Styrene Oxidation
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Date
2012-03
Authors
Koohestani, Behnam
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The oxidation of olefin compounds to equivalent epoxides or oxides using
metal oxides as catalyst is an important step in the manufacturing of large quantities
of fine and pharmaceutical grade chemicals. The chemical property of vanadium as
metal in its oxide state is of interest particularly in application during o le
e oxidation. Well-defined metal oxide nanostructures on the walls of carbon nanotubes
(CNTs) are attractive as catalyst in the oxidation reaction because of their high
specific surface area and formation of novel composite material with enhanced
physical and catalytic properties. In this work, a thin layer of VxOy- " -Al2O3
# # $ * ,
capability. Metal oxide nanocomposite VxOy/CNT was prepared by wet
impregnation method dispersed in sol, AlOOH. It was then coated on the surface of
support through sol-gel technique. Factors that affect the preparation of defect free
coating such as type of binder, time for the addition of binder to sol and surface
treatment of the support, were investigated. The physical and chemical properties of
the unsupported and supported membrane were characterized using different
techniques such as SEM, TEM, FTIR, TGA, AFM, XRD and nitrogen adsorptiondesorption.
Design of experiments (DOE) was applied to optimize the styrene oxidation
conversion and benzaldehyde selectivity using the prepared membrane and
nanocomposite catalyst. The optimal oxidation conditions were achieved at reaction
$ +' $ difference of 1.5 bar, molar ratio of
H2O2/styrene of 1.5:1 and loading of 30 wt. % catalyst on membrane. These
conditions resulted in maximum styrene conversion of 25.6% and benzaldehyde
selectivity of 84.9%. In the case of nanocomposite catalyst (VxOy/ -Al2O3), optimum
oxidation conditions were reaction temperature of 62.74 '-*' molar
ratio of H2O2/styrene of 2.7:1 and catalyst loading of 0.34 g for maximal styrene
conversion of 68.23% and maximum benzaldehyde selectivity of 57.32%.
Description
Keywords
Mixed matrix vanadium oxide catalytic , nanocomposite membrane