International Journal of Chemical Reactor Engineering, Vol. 10 No. 1
(2012)
Effect of Chitosan Addition on NiMo/Al2O3 Catalysts
for Dibenzothiophene Hydrodesulfurization
Ríos-Caloch, Guillermina 1 / Santes, Víctor 2 /
Escobar, José 3 / Valle-Orta, Maiby 4 / Barrera, María C. 5 /
Hernández-Barrera, Melissa 6
1 CIIEMAD-Instituto Politécnico Nacional (email)
2 CIIEMAD-Instituto Politécnico Nacional (email)
3 Instituto Mexicano del Petróleo (email)
4 Instituto Mexicano del Petróleo (email)
5 Facultad de Ciencias Químicas, Universidad Veracruzana (email)
6 Instituto Mexicano del Petróleo (email)
Abstract
Reports preparation of a series of supported
NiMo catalysts by impregnating ammonium heptamolybdate and nickel nitrate over chitosan (Chi) modified Al2O3 carrier. Researchers
initially impregnated alumina substrate with the organic additive at
concentrations corresponding to Chi/Ni mol ratios of 0.5, 1 and 2.
Lower Mo dispersion in materials prepared over
Chi-modified alumina was observed by Raman spectroscopy. Additionally, in those
samples formation of hardly reducible aluminum molybdates was shown by thermal
analysis. Sulfided catalysts were tested
in dibenzothiophene hydrodesulfurization
where no improved activity was
registered for chitosan-modified samples. However, increased selectivity to the
product from direct desulfurization route (biphenyl) suggested enhanced promotion
of MoS2 phase (by Ni) in catalysts prepared with organic additive. CO
adsorption at -173 °C showed lower
concentration of NiMoS active sites over catalysts prepared over
chitosan-impregnated alumina carrier pointing out to the existence of highly
efficient sites, in spite of their lower surface concentration. This suggests
the possible use of chitosan, a sub-product from seafood industry, as efficient
HDS catalyst additive.
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