Characterization of CaO–TiO2 and V2O5/CaO–TiO2 catalysts and their activity for cyclohexanol conversion

Influence of CaO on TiO2 (anatase) phase stabilization and dispersion behaviour of V2O5 over CaO–TiO2 mixed oxide support have been investigated using XRD, FTIR, Raman, XPS, and BET surface area techniques. The CaO–TiO2 binary oxide (1:1 molar ratio) was synthesized by a homogeneous co-precipitation method from ultrahigh dilute solutions of the corresponding chlorides and calcined at various temperatures from 723 to 1273 K. On the calcined CaO–TiO2 support (723 K) various amounts of V2O5 (2.5–10 wt.%) were deposited from ammonium metavanadate by a wet impregnation method and calcined at different temperatures. Conversion of cyclohexanol to cyclohexanone/cyclohexene was performed as a model reaction to assess the acid–base properties of the prepared catalysts. The CaO–TiO2 composite oxide exhibits reasonably high specific surface area and high thermal stability up to 1273 K retaining titania-anatase phase. The deposited V2O5 over CaO–TiO2 support is present mostly in a dispersed form. Further, a strong and preferential interaction between the basic CaO and the dispersed V2O5 leads to the formation of CaVO3 and the physicochemical properties of the prepared catalysts are clearly reflected in their catalytic activity.