Catalytic Ammonia Synthesis over Mo Nitride/ZSM‐5

Abstract Molybdenum nitride species in HZSM‐5 are prepared by the reaction of ammonia with MoOx, which is pre‐exchanged into the channel of HZSM‐5. Both the processes of solid exchange of molybdenum oxide with the zeolite and the ammonia reaction are monitored by mass spectrometry. The Mo/N ratio of the MoNx species in the Mo nitride/HZSM‐5 is close to 2, as measured by temperature‐programmed oxidation. The MoNx species are more stable than bulk Mo2N against oxidation, due to the interaction between the molybdenum nitride species and the charged zeolite framework. The MoNx species, of which the dispersion is found to be greater than 90 %, are very active in ammonia synthesis and the catalytic activity is much more stable than that of bulk Mo2N. The reaction pressure is much more favorable to ammonia formation on the MoNx/ZSM‐5 catalyst than on bulk Mo2N. The interaction of nitrogen molecules with the inner electric field of the zeolite, at an equivalent pressure, enhances the reaction of ammonia synthesis.