Following the crystallisation of Bi2Mo2O9 catalyst by combined XRD/QuEXAFS

The formation of b-phase Bi2Mo2O9 catalyst from a precursor precipitate has been studied using the in situ combined XRD/QuEXAFS technique and DSC during calcination. Accordingly the precursor was observed to undergo a number of changes in both the molybdenum (VI) coordination and long-range ordering during this heating. Initially the two other forms of bismuth molybdate (a- and g-phases) were observed to form from the poorly crystalline precursor at about 230C, however, the b-phase eventually crystallised after prolonged heating at 560C.