High-surface-area SiO2-ZrO2 prepared by depositing silica on zirconia in aqueous ammonia solution

Preparation of high-surface-area SiO2-ZrO2 by deposition of silicate specie s on zirconia under hydrothermal conditions in an aqueous ammonia solution was investigated. A fresh precipitate of ZrO(OH)(2) was heated in a pressur e vessel with several pieces of quartz glass tube at 100 degreesC. In the m easurement of ICP-AES and solid-state Si-29 NMR, it was elucidated that a s ilica component dissolved from the glass in the basic solution was deposite d on the ZrO(OH)(2) precipitate and that the silica content increased with increasing hydrothermal period. The resulting SiO2-ZrO2 had a specific surf ace area higher than 240 m(2) g(-1) even after calcination at 500 degreesC. In contrast to the pure ZrO2 particles readily aggregating, the silicate s pecies deposited on the surface of ZrO2 particles prevented the agglomerati on of the primary particles during calcination, resulting in high-surface-a rea SiO2-ZrO2. (C) 2000 Academic Press.