Synthesis of Spherical Porous Zirconia and Titania Particles in W/O Emulsion

Abstract

Spherical porous zirconia and titania particles were synthesized by the sol-gel process from zirconyl chloride, zirconium tetrapropoxide and titanium tetraisopropoxide in W/O emulsion, respectively. Zirconia particles are obtained by addition of urea and hexamethylenetetramine in a starting solution. When the molar ratio of zirconyl chloride, calcium chloride, urea, hexamethylenetetramine, N, N-dimethyl formamide and H2O is 1:0.2:1.1:0.9:1.4:45, spherical porous zirconia particles could be synthesized. The particles occurred cubic and monoclinic form at 600°C, respectively. Peak pore-diameter of the particles was 4nm. The pore volume increases with increase in calcium content. After the extraction of calcium by hot water, the specific surface area of the particles is enhanced 110m2/g. SiO2-ZrO2 binary particles are synthesized by using zirconium tetrapropoxide and 2-methoxyethanol. When the molar ratio of tetramethoxysilane (TMOS), zirconium tetrapropoxide, 2-methoxyethanol, H2O and HCl is 0.7:0.3:5.25:20:3.6×10-4, the specific surface area of the particles was 260m2/g. After the extraction of SiO2 parts by 1M NaOH aqueous solution, the weight loss of the particle was 10mass%. Titania particles are obtained by addition of diethanolamine or 2-methoxyethanol in starting solution. Peak pore-diameter of the particles is 4nm when the molar ratio of diethanolamine to titanium tetraisopropoxide was 1.5. By calcination at 500 and 700°C, the particle occurred anatase and rutile type, respectively. TiO2-SiO2 binary particles are synthesized by using 2-methoxyethanol. When the molar ratio of titanium tetraisopropoxide, TMOS, 2-methoxyethanol, H2O and HCl is 0.4:0.6:4:20:1.8×10-3, the specific surface area of the particles was 180m2/g after the extraction of SiO2 parts by 0.1M NaOH aqueous solution.