Integrating Dissociative and Associative Routes for Efficient Ammonia Synthesis over a TiCN-Promoted Ru-Based Catalyst

Dinitrogen activation in ammonia (NH3) synthesis usually obeys either the dissociative or associative route. We report here a combination of dissociative and associative routes over a titanium carbonitride (TiCN)-promoted Ru-based catalyst to achieve an outstanding NH3 synthesis rate. The developed Ru/3TiCN/ZrH2 catalyst shows a superior NH3 synthesis rate of 25.6 mmol gcat –1 h–1 at 400 °C and 1 MPa. Our studies reveal that TiCN transfers electrons to the Ru centers and reduces the aggregation of Ru metal particles to generate more B5 sites, thus accelerating the dissociation of N2 to form NH3 via a dissociative route. Meanwhile, the facile formation of nitrogen vacancies on TiCN assisted by Ru enables the associative mechanism initiated with N2 hydrogenation to form *NNH. The synergistic effect of Ru and TiCN on N2 activation via integrating the dissociative and associative mechanisms accounts for the superior NH3 synthesis rate of our catalyst under mild conditions.