Following the formation of gamma-phase Bi2MoO6 catalyst by in situ XRD/XASand thermogravimetric techniques

We report a detailed bl situ study of the preparation of the gamma-phase Bi 2MoO6 catalyst from a gel. In particular, the local coordination around mol ybdenum remained tetrahedral, although the poorly crystalline bismuth molyb date phase started to appear below 400 degrees C; above this temperature th ere was a distinct change in the coordination around molybdenum to a distor ted octahedron. Combining the information obtained from TGA, DTA, combined XRD/XAS and DRIFT techniques, me mere able to track clearly the changes in the local coordination around the molybdenum as well as the loss of mater a nd ammonia molecules during the course of the formation of the crystalline gamma-Bi2MoO6 phase from a poorly crystalline material. (C) 1999 Academic P ress.