Building block approach to SiO2-ZrO2 porous materials

(2-Hydroxyethyl)trimethylammonium silicate, Si8O20[N(CH3)(3)(C2H4OH)](8). nH(2)O, was allowed to react with zirconium tetrakis(2,4-pentanedionate) in methanol, resulting in gel formation, The gels were heat-treated at 650-1000 degrees C in air. The product at 650 degrees C showed a specific surface area of 500 m(2) g(-1), and the average pore diameter was ca 4.3 nm, indicating the formation of a thermally stable mesoporous body. Gels with the same composition were also prepared by sol-gel processing using tetraethoxysilane as a silica source, The specific surface area of the product yielded by heating the gels at 650 degrees C was 425 m(2) g(-1) and the average pore diameter was ca 2.8 nm, which were lower than those of the product from the gels prepared with (2-hydroxyethyl)trimethylammonium silicate. These differences have been attributed to the difference in nanostructure of the gels, caused by the structure of the silica sources and their polymerization behaviour, Copyright (C) 1999 John Wiley & Sons, Ltd.