MAS NMR Strategies for the Characterization of Supported Molybdenum Catalysts
Résumé
After recalling a few advances on the understanding of hydrodesulfuration (HDS) molybdenum-based catalysts supported on amorphous oxides made by 1H, 29Si, and 27Al, we critically evaluate the potential of 95Mo magic-angle spinning nuclear magnetic resonance (MAS NMR) for gaining further insight into the structure of uncalcined precursors and sulfided HDS catalysts. It is shown that when performed at a very high field (19.6 T), it is indeed sensitive to the nature of the molybdenumsupport interaction. In particular, a wide distribution of the molybdenum environment present on the surface was evidenced. However, the possibility to characterize sulfided catalysts by 95Mo MAS NMR appeared still an unmet challenge.