Monolayer V205/Ti02 and MoO,/TiO, catalysts prepared by different methods

Two series of supported V,O,/TiO, and MoO,/TiO, catalysts were synthesized using different preparation methods to determine the possible influence of the preparation procedures upon the final molecular structures of the catalysts. It has been found by means of ambient and in situ Raman spectroscopy that all the employed preparation methods lead to the same types of surface metal oxide species on the titania support. The hydrated surface metal oxide species of both series of the catalysts undergo, after heating in flowing dry air, reversible conversion into the dehydrated analogues. The preparation methods appear to have no influence on the final surface metal oxide structures, but can affect (delay) the process of their formation, as in the case of dry impregnation (thermal spreading) of the V,O,/TiO, system, due to the thermodynamic and diffusion factors involved.