Mesoporous titania modified with tungstophosphoric acid: synthesis and characterization

LUIS RENE PIZZIO; M. FUCHS, VANESA; EDGARDO SOTO

Turku/Abo, Finlandia

Congreso; VIII Europacat Conference; 2007

Since the photocatalytic degradation of pollutants was introduced, the preparation of photocatalysts with high catalytic performance has attracted much attention. Among several photocatalysts, TiO2 (in anatasa phase) has been the most widely used because it is easily available, inexpensive, non-toxic, and shows relative high chemical stability. The photocatalytic activity of titania is influenced by the crystal structure, crystalinity, surface area, band gap, porosity and surface hydroxyl group density [1,2]. However, the shortcomings of conventional powder catalysts include low efficiency of light use, difficulty of stirring during reaction and separation after reaction [3]. Hole-electron recombination and low surface area are considered among the most important disadvantages of TiO2 that result in low photocatalytic activity in practical applications. Therefore the photo catalytic activity of TiO2 based catalysts can be improved by separation of the electrons and holes and the increase of the surface area. It is known that doping with suitable metal ions allows extending the light absorption of large band-gap semiconductors to the visible region [4]. Heteropolyoxometalates have been used to modify TiO2 in order to reduce the charge recombination. They have been added to TiO2 suspensions [5], incorporated into TiO2 colloids [6] or anchored to TiO2 by chemical interactions [7]. In addition, the incorporation of POMs into titania matrix can improve the densities of catalysts and makes it easy to separate them from heterogeneous reaction systems for recycling. Titania with large surface area was reported to be suitable to obtain high catalytic performance and can be synthesized using urea as low cost template via sol-gel reactions [8]. We present here the preparation and characterization mesoporous titania modified with tunstophosphoric acid (TPA) obtained using urea as low cost pore forming agent, via HCl catalyzed sol-gel reactions.