Structural and textural characterization of sol–gel prepared nanoscale titanium–chromium mixed oxides

Chromium–titanium mixed oxides with Cr/Ti + Cr molar ratio of 0.1, 0.2, 0.5, and 0.9 were prepared by a direct sol–gel method. The products were characterized by powder XRD, FT-IR spectroscopy, TEM, and N2 adsorption. Starting with 10% Cr3+, Cr/Ti + Cr = 0.1, resulted in a complete dispersion of the Cr3+ ions in the titania matrix. On the other hand, a ratio of 0.2 resulted in the formation of traces of segregated α-Cr2O3, besides Cr-doped titania. At higher Cr contents, %Cr of ≥ 50, crystalline Ti-doped Cr2O3 and an amorphous Cr-doped titania were obtained. Compared with the corresponding one-metal oxides, TiO2 and α-Cr2O3, the mixed oxides showed significantly modified textural properties presented in higher surface areas, larger porosities, and more homogeneous mesoporous structures. In addition, the incorporation of Cr3+ ions in the titania lattice enhanced the thermal stability of the anatase phase against transformation to rutile.