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

Abstract

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 Mo2N-Mo couple and experimentally validate its N fixation and N release steps under mild conditions. In the N-release step, the NH3 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 Mo2N. In the N-fixation step, the introduction of H2 enhanced the reaction kinetics between Mo and N2, 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 Mo2N as an NC during the CLAS process.