Preparation, Characterization, and Catalytic Behavior of Molybdenum Oxynitrides Supported on EMT Zeolite (NaEMT and HEMT) Catalysts

Author： Bécue T. Manoli J-M. Potvin C. Djéga-Mariadassou G.

Publisher： Academic Press

ISSN： 0021-9517

Source： Journal of Catalysis, Vol.170, Iss.1, 1997-08, pp. : 123-131

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Abstract

EMT zeolite-encaged molybdenum oxynitride clusters were prepared byseveral methods, leading to different dispersions of the molybdenumspecies. HRTEM and EDX measurements indicated that, when the molybdenumspecies were inside of the zeolite porosity, they werehomogeneously dispersed in the form of clusters whose diameters were less than 10 Å. Depending on the preparation, it was shown by X-raydiffraction and specific surface area measurements that the EMTzeolite crystallinity was affected to different extents followingammonia treatments used for nitridation. The catalytic behavior ofthese nitrided compounds was studied in then-heptaneconversion. Supported on NaEMT, the encaged molybdenum oxynitrideshowed a reactivity of a bulk material. The most active catalystwas the low-temperature (523 K) catalyst, then-heptaneisomerization appearing as the main reaction. In contrast, for thecatalysts supported on acidic HEMT,n-heptane cracking wasmainly observed and the deactivation of the Mo-oxynitride supportedcatalysts was lowered compared to that of HEMT alone.