Effect of P content in the conversion of guaiacol over Mo/γ-Al2O3 catalysts

• The highest conversion of guaiacol was obtained using MoP(1.0)/γ-Al2O3 catalyst.
• The activity increased due to the formation of two-dimensional MoS2 species, promoted by PO4−3 species.
• The different phenol/catechol ratios were due to the acid strength of the catalysts induced by the presence of phosphorous.

The effect of phosphorus content on Mo/γ-Al2O3 sulfide catalysts for the conversion of 2-methoxyphenol (guaiacol) was studied. The catalysts were prepared by successive impregnation of P (0.5, 1.0, 2.0. 3.0 and 5.0 wt.%) and then Mo (15 wt.%) precursors in excess solvent. The activities of the catalysts were evaluated in the hydrodeoxygenation (HDO) of guaiacol, carried out at 573 K and 5 MPa. The catalysts were characterized by BET surface area, UV-vis-DRS, electrophoretic migration (EM), X-ray Photoelectron Spectroscopy (XPS) and surface acidity techniques. The conversion of guaiacol increased with increase in P content up to 1.0 wt%, and then subsequently decreased at higher loadings. The increase in activity was attributed to the formation of two-dimensional MoS2, while the subsequent decrease was ascribed to loss of active sites resulting from the formation of three-dimensional MoS2. The differences in surface Mo species present on the catalyst were related to the amount of P contents. On the other hand, differences in selectivity, expressed in terms of the phenol/catechol ratio, were mainly influenced by the acid strength of the catalysts.

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