The modification of MoO3 nanoparticles supported on mesoporous SBA-15: characterization using X-ray scattering, N2 physisorption, transmission electron microscopy, high-angle annular darkfield technique, Raman and XAFS spectroscopy

摘要: MoO3 was dispersed onto mesoporous SBA-15 by using ammonium heptamolybdate as source. The formation of carried out heating the loaded material to 500 °C for 3 h in air. Below 13 wt% Mo loading, no reflections occur X-ray powder patterns and even high contents, intensities are much lower than expected fully crystalline material. A detailed XAFS analysis reveals that at low metastable hexagonal modification is formed despite calcination temperature 500 °C. It highly likely nanosize particles interaction between stabilize Nitrogen physisorption experiments show typical type-IV isotherms indicating mesoporosity materials preserved large amount MoO3. Transmission electron micrographs demonstrate presence inside support. Raman spectra display a remarkable size-dependent intensity loss several features give evidences bond nano-sized silica Moreover, spectroscopic details suggest (MoO3)n oligomers. nanoparticles successfully introduced into pores SBA-15. Up about amorphous higher loadings still not crystalline. transmission microscopy retained. At appears be stabilized with support (XAFS).