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

Abstract

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 5.0wt.%) and then Mo (15wt.%) precursors in excess solvent. The activities of the catalysts were evaluated in the hydrodeoxygenation (HDO) of guaiacol, carried out at 573K and 5MPa. 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 1.0wt%, 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.