Catalytic properties of titania-supported heteropolyacids for ethanol oxidation

Titania supported heteropolyacids (HPA) H-3[PMo12O40]center dot xH(2)O (HPM) and H-4[PMo11VO40]center dot yH(2)O (HPVM) were prepared, characterised and tested as catalysts for ethanol conversion. Supported and unsupported samples were characterised by nitrogen physisorption, SEM, thermal gravimetric analysis and FT-IR spectroscopy. By deposition on TiO2 the thermal stability of HPA increased up to 723K. The reaction rates of ethanol conversion and acetaldehyde formation increased on supported HPA comparatively with pure HPA. The values of the apparent activation energies calculated by the "turnover frequencies" method are quite similar to the energies calculated from the reaction rates. A "compensation effect" was evidenced for acetaldehyde, ethylene and ethyl ether formation.