SYNTHESIS OF IMMOBILIZED MOLYBDENUM CATALYST FOR OXIDATION PROCESSES
SYNTHESIS OF IMMOBILIZED MOLYBDENUM CATALYST FOR OXIDATION PROCESSES
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Date
1994-06
Authors
IYUKE, SUNNY ESAYEGBEMU
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Abstract
This research work reports a general concept in liquid
phase oxidative catalysis which combined the advantages of
homogeneous and heterogeneous catalysis, by the use of a resin
immobilized molybdenum catalyst.
The immobilized molybdenum catalyst is prepared by a
sorption process, whereby the molybdenum ions are anchored on
the active sites of a polymer resin (Amberlite IRA-400 in CI
form). Experimental observations suggest that the polymer
resin probably has two active sites for sorption, and this led
to the development of a model equation for two parallel firstorder
reactions with a common product for the sorption process
as:
[Mo] = 3.47 x iO -5(0.45e-0.081t + (1 - 0 .45 )e-0.026t )
For comparison of the polymer immobilised catalyst
versus the unsupported (homogeneous) catalyst, maleic acid
(pK. = 1,83, pK, = 6.50) was selected as the model substrate,
because it can be smoothly oxidized to cis-epoxysuccinic acid
(pK1, = 1.98, pK2., = 3.92), using hydrogen peroxide in concert
with ammonium molybdate. The rate of the epoxidation
reactions was monitored by analysing the concentrations of
maleic acid, hydrogen peroxide, and the volume of oxygen
evolved due to the inevitable decomposition of hydrogen
peroxide in aqueous solutions. A maximum obtainable yield of
the epoxide was 84% at the conversion of 97% and selectivity
of 87% based on H.202 consumed with the immobilized catalyst,
while the corresponding values with homogeneous catalyst was
56% at the conversion of 76% and selectivity of 74%.
A detailed exploitation of the immobilized catalyst (in
pseudo-homogeneous system) resulted in the proposition of a
mathematical expression for the rate of epoxidation (based on
H202 consumed).
Description
A Thesis Submitted to
The Postgraduate School
Ahmadu Bello University.
In Partial Fulfillment of the
Requirement for the Degree of
M.Sc. Chemical Engineering
In Department of Chemical.Engineering,
faculty of Engineering
Ahmadu Bello University,
ZARIA
JUNE, 1994
Keywords
SYNTHESIS,, IMMOBILIZED,, MOLYBDENUM,, CATALYST,, OXIDATION PROCESSES