An Al K-edge EXAFS study of MoO3/H-ZSM-5 catalyst precursors

A study of the activation of MoO3/H-ZSM-5 precursors for dehydroaromatisation of methane catalysts has been made. Using Al K-edge EXAFS in conjunction with 27Al MAS NMR, it can be seen that there is a significant distortion of the framework Al environment, with respect to that in H-ZSM-5. In-situ FTIR studies confirm that molybdenum remains in the +VI oxidation state under the conditions employed in the EXAFS experiments, and that the acidity displayed by such precursors is exclusively of Brønsted type. Ammonia TPD experiments demonstrate that the presence of molybdenum oxo species leads to a reduction in the average Brønsted acid site strength.