CATALYTIC ACTIVITY AND STUCTURE OF MoO3 HIGHLY DISPERSED ON SiO2

Article abstract of DOI:10.1021/j100411a014

The structure of Mo-Si oxides has been investigated by XRD, FT-IR, laser Raman, and photoluminescence techniques.At low Mo content, an X-ray amorphous phase is formed, which is characterized by surface molybdates dispersed on SiO2.The surface concentration of amorphous MoO3 as well as the rate of oxidative dehydrogenation of C2H5OH shows a maximum at about 1 atom percent Mo.The change in the rate runs parallel with the change in the concentration of amorphous MoO3, i.e. surface polymolybdate.The concentration of tetrahedrally coordinated Mo ions in Mo-Si oxides determined by the photoluminescence technique shows a maximum again at about 1 atom percent Mo content, becoming zero in the range above 3 atom percent Mo content.A good parallelism between the concentration of tetrahedrally coordinated Mo ions and the rate of the metathesis reaction of propene is observed.