Epoxidation of cyclooctene over mesoporous Ga, Ga–Nb, and Ga–Mo oxide catalysts

Abstract

We demonstrate the epoxidation of cyclooctene to epoxycyclooctane over mesoporous Ga and mixed Ga–Nb and Ga–Mo oxides synthesized via self-assembly hydrothermal-assisted approach. These mesoporous catalysts displayed high epoxide selectivities at moderate cyclooctene conversions. Mesoporous Ga oxides with average particle sizes between 2 and 3 μm exhibited higher cyclooctene conversions, while larger particle sizes between ~ 4.5–6.5 μm showed lower conversions. The incorporation of Nb led to an increase in the acidity of the resultant Ga–Nb mixed oxides. These mesoporous Ga–Nb mixed oxides displayed 80–100% selectivity for the epoxide at conversion levels of cyclooctene in the 17 to 30% range. Finally, a mesoporous Ga–Mo oxide with molar composition of 35% Mo displayed the highest cyclooctene conversion of all mesoporous samples at 60 °C. The conversion of this sample was 41% with 100% selectivity.