Generation of Highly Active Nanocrystals on Tungstated Zirconia
N. Soultanidis, A.C. Psarras, C.A. Roberts, I.E. Wachs
Rice University, US
Keywords: Nanocatalysis, Metal oxides, isomerization
Abstract:New insights into the nature of the acidic catalytic active sites that were reported recently reestablished our understanding for WOx/ZrO2. The detection of distorted Zr-WO3 nanoparticles, with higher concentrations occurring at average surface densities, engages the scientific community to revisit this well studied catalytic system. In this study, two series of WOx/ZrO2 catalysts were synthesized by incipient wetness impregnation into two commercially available amorphous metastable Zr(OH)4 supports using ammonium metatungstate precursor. Preliminary data for one of the two supports show a maximum in nC5 conversion activity at ~5 W/nm2, where increased Zr-WO3 concentrations were observed, indicating that a strong acid-demanding reaction like nC5 isomerization follows a volcano-shape dependence similar to less acid demanding reactions. Pyridine FTIR experiments gave a better insight in the acidic properties of this system. With respect to Brønsted acidity, tungstated zirconia has similar concentrations of Brønsted sites with commercial FCC equilibrium catalysts.