Photochemical activation titania

Titania is of great interest as a catalyst or photocatalyst. Matsudo and Kato have reviewed the catalytic (thermal) chemistry of TI02 (2). For photochemical activity, titania has been used to hydrogenate alk-ynes and alkenes (3), to oxidize H2O2 (4), to oxidize ethylene (5), to oxidize 2-propanol (6), for amine production (7) and in water splitting reactions (8). 

Anatase and rutile titania nanoparticles and pigmentary titania particles were used for photooxidation studies on a metaUocene PE [4] and proved to be more photochemically active than the pigment particles. On the other hand, titania nanoparticles with enhanced photocatalytic activity (anatase) may be used in nanocomposites coatings having self-cleaning properties. 

Catalysts. Titania is an active catalyst for different reactions, inorganic and organic, thermal and photochemical. It may be self-supported, or it may be supported on... 

Anatase is much more active than rutile in the liquid-phase photooxidation of 2-propanol, and the observed reactivity compared well with that of gaseous alcohol on platinized titania [106a]. Because most early studies employed the alcohol as a sacrificial reagent for the photochemical production of hydrogen, the organic product was often not analyzed and little effort was devoted to the selective activation of alcohols in the presence of other functional groups. In the oxidation of car-... 

Another example of the OBRs use with solid particles is as a photochemical reactor with solids suspension, in this case the vortical flow patterns being used to suspend catalytic titania particles to convert organics in wastewater. The tita-nia needs to be activated by ultraviolet, and the reaction requires the presence of oxygen, so air is bubbled through. The gas-liquid mass transfer is enhanced by the oscillation of the fluid, as it increases hold-up time (bubble residence time) and reduces bubble size (increasing surface area and further increasing hold-up time). The flow patterns simultaneously ensure good exposure of the titania particles to the radiation from an axially located ultraviolet lamp. 

---