WOx‐CeO2 and WOx‐Nb2O5 catalysts deactivation during hexane isomerization

Abstract

AbstractTwo series of WOx‐CeO2 catalysts containing 10, 12, and 15 wt % W were prepared by co‐precipitation and incipient wetness impregnation using a reported procedure. WOx‐Nb2O5 catalysts with the same amount of W were prepared by co‐precipitation starting from an aqueous solution of ammonium niobium oxalate and ammonium metatungstate with ammonia, until reaching pH 7. After calcining for 3 h in static air at 973 K, the deactivation of the catalysts was investigated using isomerization of hexane as probe reaction at temperatures in the range 393–513 K, both in the absence and in the presence of hydrogen. In‐situ Raman spectra during deactivation were recorded as well. The deactivation rate was fitted by an empirical Voorhies equation: R = m t−n, where the values of n correlated very well with the mass loss determined from TG analysis. © 2008 American Institute of Chemical Engineers AIChE J, 2008