Absorption of light (W or visible) by the ground state of a molecule (So) generates
electronically excited states, either directly (the singlet states) or after intersystem crossing
from the singlet manifold (the triplet states). Alternatively, triplet states may be generated by
energy transfer from another excited state (a sensitiser). In both multiplicities, very fast
internal conversion leads to the lowest states (S1 and TI respectively). These states, although
still quite short lived (typical lifetime 610-8 s for S1 and ...
Titanium oxide ST01, ST31, TiO2 catalysts modified by V5+, N2+ and supported on MCM41 and SiO2 have been used for photooxidation of p-xylene in gas phase. Physicochemical properties of catalysts were determined by the methods of BET Adsorption, Xray Diffraction (XRD), UV-Vis spectroscopy, and atom adsorption spectroscopy (AAS) methods. The photocatalytic activity of catalysts were determined after thermal treatment as well as UV lighting. The common observation is that the higher temperature of treatment the lower conversion of p-xylene obtained.