Hybrid TiO2-SiO2 organic/inorganic gels as catalysts for olefin epoxidation

Abstract Hybrid TiO 2 –SiO 2 xerogels were treated at different temperatures, and used as olefin epoxidation catalysts. All samples displayed a very high selectivity toward formation of cyclooctene oxide from cis -cyclooctene, in the presence of hydrogen peroxide and methanol. ‘All-inorganic’ (entirely TEOS-based) preparations are more subject to Ti leaching during reaction than the hybrid materials and as a consequence, they display much poorer activity recovery after recovery and re-use. The higher hydrophobicity of the hybrid samples relative to that of the conventional TiO 2 –SiO 2 alcogel is demonstrated by dynamic adsorption experiments using an oscillating balance reactor.