Ternary-Promoted Cobalt Catalyst for Ammonia Synthesis

Development of low-cost catalysts for ammonia synthesis under mild conditions is essential for advancing a sustainable society. Traditional approaches, which enhance catalytic activity via addition of alkali and alkaline earth metals to promote electron donation, face fundamental limitations. Here, we demonstrate that Ba, Ce, and Zr synergistically enhance catalytic activity in Co-Mg catalyst systems. These promoters effectively prevent sintering of both Co and MgO nanoparticles, leading to formation of a distinct grape-like nanostructure, where highly dispersed Co nanoparticles are maintained even at high Co loadings. The resulting catalyst exhibits a remarkable ammonia synthesis rate of 36.9 mmol gcat−1 h−1 at 350 °C and 1.0 MPa, positioning it as one of the most advanced non-noble metal catalysts for mild-condition ammonia production.