Cs-Promoted ruthenium catalyst supported on Ba5Ta4O15 with abundant oxygen vacancies for ammonia synthesis

Efficient ammonia synthesis is a significant but challenging target. Herein, the perovskite Ba5Ta4O15 nanosheets were prepared as a support to rationally construct Cs modified Ru/Ba5Ta4O15 (Cs-Ru/Ba5Ta4O15) for this end. The Cs-Ru/Ba5Ta4O15 catalyst exhibits high catalytic activity and stability in 72 h ammonia synthesis reaction process at 400 ℃ and 0.1 MPa. Characterizations by various physicochemical techniques reveal that Ba5Ta4O15 can be reduced, resulting in formation of oxygen vacancies (OVs) under reaction conditions. The presence of OVs in Ba5Ta4O15 significantly enhances the ammonia synthesis of the Ru based catalyst. The activation of N2 and formation of NH3 can be realized on Ba5Ta4O15 with OVs even without Ru metals. Moreover, the kinetic experiments indicate that hydrogen poisoning is greatly inhibited through promotion of hydrogen spillover from Ru to support of Ba5Ta4O15. Therefore, Ba5Ta4O15 is expected to be a promising support of Ru based ammonia synthesis catalysts.