FIGUEIREDO, J. S. B.; http://lattes.cnpq.br/9950434889786684; FIGUEIREDO, Joyce Salviano Barros de.
Resumo:
The rise in oil prices due to the recent conflicts between Russia and Ukraine,
together with uncertainties about the future depletion of oil and the environmental
impacts caused by this fuel, makes it necessary to search for alternative sources of
energy. Biodiesel is an alternative to petroleum diesel because it is produced from
renewable sources and causes less pollution in the atmosphere. This biofuel can be
obtained mainly through the transesterification reaction using vegetable oils or animal
fats with a short chain alcohol in the presence of catalysts. The heterogeneous catalyst
may be the most viable, as it can enable reuse in industrial processes. Micro mesoporous materials are relevant for heterogeneous catalysis, as they combine the
benefits of microporous materials, such as zeolites that have high acidity and selectivity
and mesoporous materials that have high surface area. The insertion of metal oxides in
catalytic supports proved to be efficient because the existence of acidic sites in these
metal oxides favors many chemical reactions. This work aimed to evaluate
molybdenum trioxide (MoO3) catalysts supported on H-ZSM-5/SBA-15 micro mesoporous structure in the production of biodiesel and to investigate the best reaction
conditions using a 23
+ 3 CtPt factorial design. Factorial design was used to evaluate the
influence of the amount of MoO3 (wt.%), reaction time and methanol: oil molar ratio on
biodiesel production. For this, ZSM-5 in ammoniacal form was introduced by the seed
method during the synthesis of SBA-15. Molecular sieve SBA-15 was synthesized by
hydrothermal synthesis using TEOS as a source of silica and triblock copolymer P123
as a targeting agent. The diffractograms confirmed the obtaining of the micro mesoporous support and the x_MoO3/H-ZSM-5/SBA-15 catalysts (where x= 6, 9 and
12 wt.%). From the textural properties, it was observed that the increase in MoO3
content decreased the specific areas and pore diameters of the catalysts. The Raman
spectra of the catalysts indicated three vibration modes corresponding to the MoO3
species in the porous structure. Statistical analysis (ANOVA) indicated that the
Methanol:oil molar ratio was the most significant parameter in the yield of methyl
esters. The maximum biodiesel yield was obtained when using the catalyst
6_MoO3/HZSM-5/SBA-15 with a methanol:oil molar ratio of 20:1 and reaction time of
4h, which resulted in 79.2% yield.