Abstract:

Supported MoFe/X (X=SnO₂, ZrO₂, CeO₂, TiO₂, CNTs (Carbon nano-tubes)), MgO and MoFe oxide catalysts were prepared for use in the catalytic conversion of glycerol to allyl alcohol. The prepared catalysts were characterized by XRD, BET, XPS, H₂-TPR, and NH₃-TPD. The results showed that Fe and Mo oxides with high chemical value (Fe³⁺ and Mo⁶⁺) predominated in MoFe/X MoFe oxide catalysts, which exhibited only weakly acidic properties. The applied supports with different physicochemical characteristics showed distinct interactions with Mo and Fe oxides, modifying the concentration of surface weak acid site, acid strength, and reducibility of MoFe/X oxide catalysts. The catalysts, based on their catalytic performance for glycerol conversion to allyl alcohol, can be ranked in terms of allyl alcohol yield as MoFe/TiO₂ > MoFe/CeO₂ > MoFe/ZrO₂ > MoFe/CNTs >> MoFe/SnO₂ > MoFe >> MoFe/MgO. Over the MoFe/TiO₂, a maximum allyl alcohol yield of 22.3% was from glycerol conversion of 83.4%, which had a selectivity of 26.7%. The MoFe/TiO₂ also showed higher catalytic stability than the MoFe/CeO₂, MoFe/ZrO₂, and MoFe/CNTs oxide catalysts. The glycerol conversion showed positive relationship with the surface weak acid concentration of MoFe and MoFe/X catalysts, while the allyl alcohol was produced over the redox sites (non-acid sites) of catalysts. With increasing reaction temperature, the glycerol conversion increased, while the allyl alcohol selectivity decreased, over the MoFe/X oxide catalysts.

Key words: Fe-Mo oxide catalysts, TiO₂, Gas-solid heterogeneous catalysis, Glycerol, Allyl alcohol