Propylene Epoxidation to Propylene Oxide Over RuO₂, CuO, TeO₂, and TiO₂ Supported on Modified Mesoporous Silicas.

Direct gas phase epoxidation of propylene to propylene oxide (PO) using O-2 is a challenging problem in catalysis research. Silica-supported ruthenium-copper-based catalysts have been recently reported to be promising for propylene epoxidation. In this work, mesoporous silica supports modified with RuO2, CuO, and TeO2 with and without TiO2 were investigated for propylene epoxidation to PO. The prepared catalysts were divided into two groups. The first group consisted of mesoporous silica supports modified with RuO2, CuO, and TeO2, and the second group consisted of the same components as the first group but adding TiO2. The prepared supports and catalysts were characterized using BET surface area analysis and other advanced instrument techniques. It was found that the catalyst made with RuO2 and TeO2 impregnated onto porous silica modified with CuO and TiO2 (denoted as RuTe/CuTiSi) exhibited an excellent PO formation of 344 gpo h(-1) kg(cat)(-1) which was superior to that of the other prepared catalysts. Moreover, the addition of TiO2 into the catalyst greatly improved the PO formation rate and the arrangement of active components in the catalyst and strongly influenced catalytic performance.