The synthesis and characterization of mesoporous silica-zirconia aerogels

A series of mesoporous SiO2-ZrO2 aerogels with various zirconia content (10-90 wt%) were prepared by the sol-gel method followed by supercritical drying. The characterization of aerogels is performed by XRD, FT-IR Si-29 liquid-state NMR, and BET-N-2 adsorption. The results showed that (i) the aerogels have type VI (BDDT) profile which is the typical of mesopores in the interval between 2 < D-p < 50 nm; (ii) the specific surface areas varied from 340 to 730 m(2)/g with (S-BET)(MAX) = 735.5 m(2)/g for the aerogel with 10 wt% zirconia and the surface areas decreased with the increase of zirconia; (iii) all the aerogels with different zirconia content remained amorphous or poorly crystallized after calcination in air at 500 degreesC; (iv) a large number of Si-O-Zr bands existed in the aerogels indicating a homogeneous distribution of the components on the atomic scale. In addition, using inorganic salt as zirconium source instead of the expensive and toxic zirconium alkoxide is very economic. (C) 2004 Elsevier Inc. All rights reserved.