Following the Formation of gamma-Phase Bi2MoO6 Catalyst by in Situ XRD/XAS and Thermogravimetric Techniques

We report a detailed in situ study of the preparation of the gamma-phase Bi2MoO6 catalyst from a gel. In particular, the local coordination around molybdenum remained tetrahedral, although the poorly crystalline bismuth molybdate phase started to appear below 400°C; above this temperature there was a distinct change in the coordination around molybdenum to a distorted octahedron. Combining the information obtained from TGA, DTA, combined XRD/XAS and DRIFT techniques, we were able to track clearly the changes in the local coordination around the molybdenum as well as the loss of water and ammonia molecules during the course of the formation of the crystalline gamma-Bi2MoO6 phase from a poorly crystalline material.