Syntheses of mesoporous zirconia with anionic surfactants

• Published in: Journal of materials chemistry 1998, Vol.8 (1), p.219-226
• Main Authors: PACHECO, G, ZHAO, E, GARCIA, A, SKLYAROV, A, FRIPIAT, J. J
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Porous materials
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/a703819d

Hexagonal mesoporous ZrO2 is of interest for use in molecular sieves. Mesoporous zirconia was synthesised by slowly hydrolysing zirconium propoxide in the presence of anionic surfactants: dodecyl phosphate or sulphate (P12 and SF12) and hexadecyl sulphonate (So16). t-Plot surface areas above 400 m2/g and diffraction lines corresponding to spacings near 4.5 nm were measured for solids outgassed at 140-150 C. This treatment does not remove the surfactant. After calcination in air at 500 C and combustion of the surfactant, the spacing increases to about 7 nm and the mesoporous volume is reduced by a factor of about 2, whereas the pore wall material crystallises in the tetragonal phase. A schematic model in which the surfactant is a scaffold component is suggested in order to explain these results. It is very different from the templating mechanisms previously reported for ZrO2. HREM revealed the presence of a disorganised network of polygonal pores in the solids obtained through the mediation of surfactant. It is suggested that the chemistry of the hydrolysis solution is instrumental in the organisation of the pore structure and in determining the thickness of the walls. In agreement with others, the fixation of PO4 or SO4 in the walls may help to preserve the porous structure. 26 refs.