SYNTHESES OF MESOPOROUS ZIRCONIA WITH ANIONIC SURFACTANTS

Synthesis of mesoporous zirconia has been performed by slowly hydrolyz ing zirconium propoxide in the presence of anionic surfactants: dodecy l phosphate or sulfate (P-12 and Sf(12)) and hexadecyl sulfonate (So(1 6)). t-Plot surface areas > 400 m(2) g(-1) and diffraction lines corre sponding to spacings near 45 Angstrom were measured for solids outgass ed at 140-150 degrees C. This treatment does not remove the surfactant . After calcination in air at 500 degrees C and combustion of the surf actant the spacing increases to ca. 70 Angstrom and the mesoporous vol ume is reduced by a factor of about 2, whereas the pore wall material crystallizes in the tetragonal phase. A schematic model in which the s urfactant is a scaffold component is suggested in order to explain the se results. It is very different from the templating mechanisms report ed for zirconia by others. The high resolution electron microscopic st udy reveals the presence of a disorganized network of polygonal pores in the solids obtained through the mediation of surfactant It is sugge sted that the chemistry of the hydrolysis solution is instrumental in the organization of the pore structure and in determining the thicknes s of the walls. In agreement with others, the fixation of PO4 or SO4 i n the walls may help to preserve the porous structure.