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

[Display omitted] • Ba 5 Ta 4 O 15 was originally applied as a support of Ru catalysts for ammonia synthesis. • 3Cs-Ru/Ba 5 Ta 4 O 15 demonstrated superior activity and stability for ammonia synthesis. • Ru accepts election from reduced Ba 5 Ta 4 O 15 and Cs-promoter for N 2 activation. • The formation of NH 3 can be realized on Ba 5 Ta 4 O 15 with OVs even without Ru catalysts. Efficient ammonia synthesis is a significant but challenging target. Herein, the perovskite Ba 5 Ta 4 O 15 nanosheets were prepared as a support to rationally construct Cs modified Ru/Ba 5 Ta 4 O 15 (Cs-Ru/Ba 5 Ta 4 O 15) for this end. The Cs-Ru/Ba 5 Ta 4 O 15 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 Ba 5 Ta 4 O 15 can be reduced, resulting in formation of oxygen vacancies (OVs) under reaction conditions. The presence of OVs in Ba 5 Ta 4 O 15 significantly enhances the ammonia synthesis of the Ru based catalyst. The activation of N 2 and formation of NH 3 can be realized on Ba 5 Ta 4 O 15 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 Ba 5 Ta 4 O 15. Therefore, Ba 5 Ta 4 O 15 is expected to be a promising support of Ru based ammonia synthesis catalysts. [ABSTRACT FROM AUTHOR]