Abstract: MoO₃ can disperse onto the surface of mesoporous sieves MCM-41 by calcining the physical mixtures of MoO₃ and MCM-41 at 773K. The state of active component
MoO₃ on ordered mesoporous MCM-41 was studied by TEM and SAED along with XRD, N₂ sorption isotherms and BJH pore size distribution. The change for MCM-41
structure was also studied after MoO_₃ dispersed onto MCM-41. The results show that the XRD peaks of bulk MoO₃ disappear completely when the loading of MoO₃
is less than the monolayer dispersion capacity. The dispersed MoO₃ can not be observed by HRTEM, while EDS spectrum evidences that there is dispersed MoO₃
in the mesopores of MCM-41. It is not possible that MoO₃ disperses onto MCM-41 absolutely by calcining when the content of MoO₃ is more than the critical
dispersion capacity. XRD, HRTEM, N₂ sorption isotherms and BJH pore size distribution results all reveal that the ordered structure of MCM-41 is destroyed for the larger
amount of dispersed MoO₃.

Key words: TEM, dispersion, MoO₃, MCM-41