Effect of solvo-thermal treatment temperature on the properties of sol–gel ZrO2–TiO2 mixed oxides as HDS catalyst supports

ZrO2–TiO2 mixed oxide (30–70 mol/mol) was prepared by low-temperature sol–gel followed by solvo-thermal treatment (1 day) at various temperatures (40, 80, 120, 160 and 200 °C). Selected samples of the corresponding single oxides were also prepared. Materials characterization was carried out by N2 physisorption, XRD, thermal analysis (TG-DTA) and UV–vis DRS, infra-red and Laser-Raman spectroscopies. Binary solids of enhanced pore volume and pore size diameter were obtained by increasing the post-treatment severity. Anatase TiO2 micro-segregation was evidenced by Raman spectroscopy for the mixed oxide solvo-treated at the highest temperature. This solid also showed the highest crystallization temperature to ZrTiO4 (∼702 °C). Mo impregnated (2.8 atom nm−2) on various mixed oxides was sulfided under H2S/H2 (400 °C, 1 h), the catalysts being tested in the dibenzothiophene hydrodesulfurization (HDS, T = 320 °C, P = 5.59 MPa). By increasing the severity of the solvo-treatment improved supports for MoS2 phase were obtained. The HDS activity of the catalyst with carrier post-treated at 200 °C was ∼40% higher (in per total mass basis) than that of sulfided Mo supported on the binary oxide solvo-treated at 80 °C. The ZrO2–TiO2-supported catalysts showed higher selectivity to products from the hydrogenation route than their counterparts supported on either single oxide.