A Study of (15)N/(14)N Isotopic Exchange over Cobalt Molybdenum Nitrides

[Image: see text] The (14)N/(15)N isotopic exchange pathways over Co(3)Mo(3)N, a material of interest as an ammonia synthesis catalyst and for the development of nitrogen transfer reactions, have been investigated. Both the homomolecular and heterolytic exchange processes have been studied, and it has been shown that lattice nitrogen species are exchangeable. The exchange behavior was found to be a strong function of pretreatment with ca. 25% of lattice N atoms being exchanged after 40 min at 600 °C after N(2) pretreatment at 700 °C compared to only 6% following similar Ar pretreatment. This observation, for which the potential contribution of adsorbed N species can be discounted, is significant in terms of the application of this material. In the case of the Co(6)Mo(6)N phase, regeneration to Co(3)Mo(3)N under (15)N(2) at 600 °C occurs concurrently with (14)N(15)N formation. These observations demonstrate the reactivity of nitrogen in the Co–Mo–N system to be a strong function of pretreatment and worthy of further consideration.