Abstract
The structural evolution of titanium oxy-hydroxide overlayers was studied for 3% and 6%TiO2/Al2O3, prepared by grafting the γ-Al2O3 support at different temperature of calcination. Results showed that during calcination the oxy-hydroxide is dehydrated at around 550 K; the γ -Al2O3 support hinders the crystallization of TiO2 anatase structure. The titanium oxide is well dispersed on the alumina surface, as confirmed by TEM and XPS data. UV-visible results showed that dried materials have small polymerization degree. A linear correlation is proposed between the position of Ti charge transfer band and the number of titanium atoms in the second coordination sfhere of titanium. This leads to the model that polymeric units [Ti(OR)4]n are grafted without modification on the support; but after calcination, linear or cyclic chains of edge-sharing TiO6 octahedra are linked to the support.
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