Beneficial Effect of W Incorporation in Supported Mo-based Catalysts for the HDO of m-Cresol

The hydrodeoxygenation (HDO) of m-cresol was investigated at 340 degrees C under 30 bar as total pressure over molybdenum oxide-based catalysts. 10 wt.% Mo were first deposited on various supports (ZrO2, TiO2, Al2O3 and COK12). The use of oxophilic ZrO2 and TiO2 supports allowed to obtain the highest HDO catalytic performances. This result could be in link with the reducibility of Mo, which was found to be dependent on the support nature. Several catalysts containing both W and Mo in oxide phase supported on ZrO2 were then prepared using various heteropolyacids as precursors (H4SiMoxW12-xO40 with x=0, 3, 6, 9 and 12). A synergy was observed between Mo and W and the best catalytic performance was obtained for SiMo9W3/ZrO2. More importantly, the presence of W improved the reducibility of Mo6+ to Mo5+ species, which quantity was correlated to catalytic activity suggesting that Mo5+ could be the active phase in HDO.