The preparation of titania doped (0.63–3.2 mmol g−1) silica (TiO2/SiO2) was described together with a mixed oxide
sample (TiO2–SiO2) at a nominal molar ratio near to 1. These materials were thoroughly characterized by XRD, N2
adsorption at 76 K and ammonia adsorption measurements as well as FTIR spectroscopy. The activity of the
materials towards 1-butene isomerization was also tested. FTIR results showed a band at 612 cm−1 attributed to bulk
TiO2 phase, in the doped 3.2 mmol g−1 TiO2/SiO2 sample, that was paralleled to an exhibited perturbation for the
SiO2 bands in the low frequency region, specifically those at 470 and 808 cm−1. The former band was similarly
obtained in the TiO2–SiO2 sample, with a lower decrease in intensity, together with the appearance of a new band
at 948 cm−1 attributed to Ti–O–Si linkages. This deed indicated the decrease in population of Ti–O–Ti bridges in
the mixed oxide sample. FTIR spectra of adsorbed D2O established the presence of different types of titania hydroxyl
groups (3615 and 3520 cm−1) that were composed during desorption of water from the titania surface. The activity
towards 1-butene isomeriztion was found to increase gradually, in the doped samples, to achieve its maximum at the
titania loading 3.2 mmol g−1, however, a tremendous decrease was obtained for the mixed oxide sample. This
behavior was correlated with the acidity of the samples. The dependence of the reaction on either Ti–O–Ti or
Ti–O–Si sites was evaluated and discussed. |
