Study of the reduction of MoO3γAl2O3 and WO3γAl2O3 catalysts by laser raman spectroscopy

Abstract Various pretreatements on those catalysts (oxide form) followed by H 2 reduction show that the primary effect of H 2 is a dehydration reaction. At high Mo loading, Two consecutive steps of reduction are evidenced: (i) formation of Mo (V) species as Mo(V)OH and (ii) formation of Mo(IV) species characterized by a (X =V, IV) bridge whose stretching mode is about 760 cm −1 . Low Mo loading samples are more difficult to reduce. By comparison with the Mo catalysts, the Wo 3 γAl 2 O 3 samples are less easily reducible but a similar initial reduced state has been found.