Abstract:

The substitution of Si⁴⁺ by Ti⁴⁺ in titanosilicates is always limited, originally, Taramasso et al. prepared TS-1 with more than≈2wt% titanium in the lattice. Both XANES and XPS allow to titrate framework tetrahedral Ti and extra-framework TiO₂ anatase species. There was no detectable extra-framework Ti up to 1.5wt% Ti, above 1.5%. A limit of ca.1.8% of Ti incorporation into the framework of the S-lsilicalite has been calculated by titration using Raman spectroscopy or using voltametric measurments, XRD and Rietveld calculation of the unit cell expansion led to higher limit of ca.2.5%. Higher level of incorporation of as much as ca.6 and 8% were claimed. Therefore, the maximum of Ti incorporation is still a controversial matter that prompted us to develop a new technique to quantify them.