Influence of ZrO2 and ZrV2O7 on the polymorphic transformation of anatase into rutile

The effect of ZrO2 and ZrV2O7 on the polymorphic transformation of anatase to rutile in the TiO2–V2O5, TiO2–ZrO2, TiO2–ZrV2O7, and V2O5–TiO2–ZrO2 systems has been investigated. It is shown that the temperature and duration of the heat treatment influence on the anatase stability in the investigated binary and ternary systems. It is established that V2O5 and ZrV2O7 accelerate the polymorphic transformation of anatase to rutile, but ZrO2 inhibits the phase change. Taking into account the ratio between V2O5, ZrO2, and ZrV2O7, formed in the ternary system, it is possible to maintain a definite quantity of anatase in a catalyst system. This permits one to influence the activity and selectivity of the modified vanadium oxide catalysts in the oxidation and ammoxidation of alkylbenzenes and alkylpyridines.