Sol-gel synthesis of silicalite/γ-alumina granules

Spherical silicalite/gamma -Al2O3 composite granules of about 2 mm in diameter were prepared by a sol-gel process from a mixture of the stable boehmite and silicalite sols. The stable silicalite sol was prepared by a hydrothermal method. Silicalite/gamma -Al2O3 composite granules with a zeolite content of up to 70 wt % were formed by the sol-gel "oil-drop" process in which a paraffin oil and ammonia solution were used as the media to facilitate shape forming and consolidation of the gel structure. The sol-gel-derived silicalite/gamma -Al2O3 granules have a pore structure reassembling that of a mixture of silicalite and gamma -Al2O3 powders. The crush strength of the sol-gel-derived silicalite granules is about six times that of a similar commercial silicalite granule. In addition, the sol-gel-derived silicalite/gamma -Al2O3 granules exhibit better sorption properties-for SO2 at a lower SO2 partial pressure than pure silicalite powder.