Molybdenum-based nitrogen carrier for ammonia production via a chemical looping route.

Chemical looping ammonia synthesis (CLAS) is an innovative and effective method for sustainable ammonia generation, in which efficient N release/fixation of nitrogen carriers (NC) is required for successive ammonia production. Herein, we report a two-step CLAS mediated by a Mo 2 N-Mo couple and experimentally validate its N fixation and N release steps under mild conditions. In the N-release step, the NH 3 production rate at 450 °C (> 4576 μmol g−1 h−1) was three times higher than that obtained via the thermo-catalytic ammonia synthesis route catalyzed by Mo 2 N. In the N-fixation step, the introduction of H 2 enhanced the reaction kinetics between Mo and N 2 , accelerating NC regeneration. In addition, only a slight deactivation of NC was observed during the 8-cycle stability test. This study confirmed the preliminary feasibility of using Mo 2 N as an NC during the CLAS process. [Display omitted] • Two-step CLAS mediated by a Mo 2 N-Mo couple was reported. • Mo-based nitrogen carriers (NC) were synthesized via a facile pyrolysis method. • Three times more NH 3 was produced via hydrogenation of NC than by thermocatalysis. • The presence of H 2 significantly improved the nitridation rate of Mo. • The NH 3 production rate kept at ~ 100 μmol g−1 h−1 during an 8-cycle stability test. [ABSTRACT FROM AUTHOR]