Abstract
The combined acid-base and redox properties of active Cu, Ni and
Co-promoted Mo catalysts supported on Al2O3 spheres have been
investigated for the gas-phase dehydration of glycerol. Al2O3 spheres
used as supports were impregnated with an aqueous resin containing metal
precursors that was synthesized by the polymeric precursor method. The
supports and catalysts were characterized by means of chemical analysis,
XRD, H-2-TPR, N-2-physisorption isotherms, SEM-EDS, CO2-TPD, TG/DTA and
pyridine adsorption isotherms. The results show differences in
morphological, textural and acid-base properties, whereas the XRD and
H-2-TPR analyses point to a good dispersion of the metal precursors. The
H-2-TPR analysis shows that the addition of Co, Cu or Ni affects the
reducibility of the Mo6+ species, which results in a shift of the H-2
consumption peaks to a lower temperature. The addition of Mo resulted in
a higher catalytic conversion, particularly for the sample containing Cu
(CuMoAl). This improvement in the catalytic performance is possibly
related to the presence of active Cu1+/Cu-0 and Mo5+/Mo4+ redox species.
Although all catalysts favour glycerol dehydration with higher acrolein
selectivity, it was found that the redox properties of the Mo species
play an important role in the product distribution, which leads to allyl
alcohol production with decreased hydroxyacetone yield.
Links and resources
Tags