Studies of parameters affecting sol-gel process of sodium tris(glycozirconate) toward the preparation of ZrO2

Abstract

Zirconium dioxide, or Zirconia, (ZrO2) was prepared by sol-gel method using sodium tris(glycozirconate) as precursor. An enormous advantage of this precursor is its reduction in reactivity with water. It can be synthesiaed using the inexpensive, well-estabished OOPS method. Zirconia having the maximum surface area of 125 m2/g was formed at a pH of 11-12 and a water to precursor molar ratio of 587 after calcining at 600C for 4.5 hours. The time required for gel formation had an influence on the physical properties of zirconia, and was controlled by varying the acid and base content or pH of the solution. The molar water to precursor ratio had no influence on the physical properties of zirconia. The amorphous zirconia became crystalline, in the form of a tetragonal phase, after heating at 500 C. X-ray diffraction data showed that heating to higher temperatures caused the zirconia to transform into the monocilinic phase after calcining at 700C. Finally, the acid-base properties of the catalysts were measured using temperature-programmed desorption (TPD) of ammonia and carbon dioxide, respectively. TPD results showed that surface area and pore volume were strongly affected by the acidity and basicity of the ZrO2.