About the importance of surface W species in WO x/Al 2O 3 during n-butene skeletal isomerization

Abstract

WO x /Al 2O 3 is accepted as an active catalyst for the skeletal isomerization of n-butene. We have analyzed the effect of preparation conditions on the properties of WO x /Al 2O 3. Catalysts were prepared by an equilibrium-adsorption method followed by different drying procedures and they were characterized by TPR, laser Raman spectroscopy, NH 3-TPD, XRD and catalytic activity and selectivity. The active catalysts present Raman bands and TPR profiles that indicate the presence of tetrahedrally coordinated WO x species. The poorly active catalysts show, in addition, WO x species in octahedral coordination which decrease total acidity and disrupt the contiguous tetrahedral sites necessary for the bimolecular reaction mechanism.