Highly selective and recyclable MoO3 nanoparticles in epoxidation catalysis

Molybdenum trioxide (MoO3) nanoparticles with an average size below 100 nm were prepared by solvothermal synthesis of nano-crystalline molybdenum dioxide (MoO2) and subsequent thermal oxidative annealing. The successful preparation of this type of nanoparticles was confirmed by evidence obtained from characterization by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) analysis and Fourier transform infrared spectroscopy (FTIR). The MoO3 nanoparticles were tested as catalytic precursor in the epoxidation of cis-cyclooctene, styrene, R-(+)-limonene and trans-hex-2-en-1-ol, using tert-butylhydroperoxide (tbhp) as oxygen source under different reaction conditions, namely, various solvents and temperatures. The catalytic studies show that the MoO3 nanoparticles perform selective epoxidation of the tested substrates with very high yield, especially at high temperature and using toluene as solvent. Furthermore, the catalyst remains active across several reaction cycles with virtually no loss of activity.