110
G. Mitran et al. / Journal of Molecular Catalysis A: Chemical 370 (2013) 104–110
ilar vanadia content, i.e. 10 wt%, for which the conversion decreased
by 15% after three reaction cycles [24], the 10Mo1V9Al catalyst
had a much better stability. This suggests indeed that molybdena
and vanadia interact on the catalyst surface increasing the catalyst
stability [26]. Additionally, based on the DR–UV–Vis results, the
polymerized VO6 species present on the catalyst surface seem, in
particular, to be responsible for the catalyst instability during the
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4. Conclusion
MoO3–V2O5 catalysts supported on ␥-alumina act as efficient
and stable solid acid catalysts for the esterification of acetic acid
with n-butanol. The catalytic activity correlated well with the
number of strong acid sites which increased by increasing the vana-
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at 120 min reaction time in parenthesis): Al2O3 (41%) < 5Mo9V1Al
(46%) < 10Mo9V1Al (62.5%) < 5Mo1V9Al (68.3%) < 10Mo1V9Al (71%).
In all the esterification reactions the selectivity for butyl acetate
was 100%. Reactant pre-adsorption experiments suggested that the
reaction follows the Langmuir–Hinshelwood mechanism with a
stronger adsorption of n-butanol than acetic acid.
The optimum reaction time was about 150 min and the optimal
mass fraction of the catalyst in the reaction medium was found
to be around 1 wt%. A good reusability of the catalysts after three
reaction cycles was observed. A local interaction between molyb-
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Compared with V2O5/Al2O3 with similar vanadia loadings, the
MoO3–V2O5/Al2O3 catalysts showed not only an increased stabil-
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