The structure of the peroxo species in the TS-1 catalyst as investigated by resonant Raman spectroscopy

The application of Resonant Raman spectroscopy allows, for the first time, to demonstrate that the species associated with the yellow color (LMCT band at 26000 cm-1) of the TS-1/H2O2/H2O system is a side on Ti-peroxo specie. This result has been achieved by using a laser source on the LMCT band. Comparison with the results obtained on model (NH4+)3(TiF5O2)3- demonstrate that the 442 nm excitation results in a strong enhancement of the Ti(O)2 breathing mode at 618 cm-1, characteristic of “side on species”. The assignment is also validated by comparison with results obtained by contacting Ti-free-silicalite with H2O/H2O2 solution.