MoO3@SiO2 nanoreactors: Synthesis with a thermal decomposition strategy and catalysis on alkenes epoxidation

• Published in: Journal of solid state chemistry Vol. 264; pp. 156 - 164
• Main Authors: Shen, Yirui, Jiang, Pingping, Wang, Yingchun, Bian, Gang, Wai, Phyu Thin, Dong, Yuming
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.08.2018
• Subjects: Alkenes; Epoxidation; Molybdenum trioxide; Nanoreactor; Thermal decomposition; Molybdenum trioxide; Epoxidation; Alkenes; Thermal decomposition; Nanoreactor
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2018.05.005

A general thermal decomposition strategy is reported to fabricate MoO3@SiO2 nanoreactors, with a mesoporous silica shell and embedded MoO3 nanoparticles. The novel preparation procedure involves mixing certain mass ratio of (NH4)6Mo7O24·4H2O (AMM) and hollow mesoporous silica spheres (HMSS) by grinding, fusion and thermal decomposition of (NH4)6Mo7O24·4H2O under calcination and removing the residual via filtration. The as-prepared MoO3@SiO2 nanoreactors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), N2 adsorption/desorption and X-ray photoelectron spectra (XPS). The nanoreactors were utilized in epoxidation of alkenes and displayed high catalytic activity and stability. The mass ratio of AMM and HMSS greatly affected the properties and catalytic performance of the nanoreactors. The optimal mass ratio of AMM: HMSS has been confirmed as 1/2. After reacting for 12 h with H2O2 (50 wt%) as oxidant, conversion and selectivity of optimal MoO3@SiO2-400-1/2 almost reached up to 98% and 99%, respectively. Furthermore, the catalyst still had high conversion (78%) and selectivity (95%) at 4 h epoxidation of cyclooctene after recycling for 6 runs. Kinetics study was also carried out and demonstrated the epoxidation of alkenes follows the first order model. A thermal decomposition strategy is employed to fabricate MoO3@SiO2 nanoreactors with a mesoporous silica shell and embedded MoO3 nanoparticles, showing promising reactivity and stability in epoxidation of alkenes. [Display omitted] •A thermal decomposition strategy applied in fabricating MoO3@SiO2 nanoreactors.•Efficient catalysts in epoxidation of alkenes with high reactivity and stability.•Kinetics study on epoxidation of alkenes which follows the first order model.