Synthesis and characterization of mesoporous and nano-crystalline phosphate zirconium oxides

In this work the preparation and characterization of the materials such as zirconia (ZrO₂) and zirconia promoted with phosphate ion (ZrO₂-PO₄^3-) is presented. Pure zirconium hydroxide [Zr(OH)₄] was synthesized by the sol-gel method using precursors such as zirconium n-butoxide and 1-butanol maintaining a pH 8 during the synthesis. Zr(OH)₄ was impregnated with 15 wt.% of the acid agent. Both were calcined in a dynamic air atmosphere for 3 h at 400, 500 and 600 °C. The supports were characterized by thermal analysis, X-ray diffraction, nitrogen physisorption as well as infrared spectroscopy. The results showed a positive effect on the physicochemical properties of the catalytic supports after Zr(OH)₄ impregnation with the dopping agent (H₃PO₄). Phosphate zirconium oxides remained thermically stable after calcination. It was observed that the dopping agent remained firmly attached to the zirconium oxide surface, inhibiting the particle growth and delaying the syntherization of the material and the apparition of the monoclinic phase, obtaining mesoporous and nano-crystalline materials (crystallite size 1.0-6.5 nm) with high surface areas (210-329 m²/g) and tetragonal structure defined for the calcination temperature of 600 °C.