Oxygen Vacancy-Rich Pr6O11: Unlocking Superior Catalytic Support for Efficient Ammonia Synthesis

Abstract

Developing effective support materials is crucial for enhancing the performance of transition metal-based catalysts, thereby enabling efficient ammonia synthesis under mild conditions. In this study, we synthesized a series of praseodymium oxides (Pr6O11) with exceptionally high oxygen vacancy concentrations (up to 74%) after activation and demonstrated their potential as robust supports for Ru-based catalysts. By leveraging the regrowth of Pr(OH)3, high-index facets were introduced, resulting in the formation of abundant oxygen vacancies in the final Pr6O11 structures. The Ru/Pr6O11 catalysts exhibited outstanding performance in ammonia synthesis, characterized by high catalytic activity and strong resistance to H2 poisoning. Under reaction conditions of 400oC and 0.1 MPa, the 2wt% Ru/Pr6O11 catalyst achieved an ammonia production rate of 4.4 mmol∙g−1∙h−1 and maintained this performance for over 100 hours, significantly outperforming Ru catalysts supported on other oxides. Furthermore, the 5wt% Ru/Pr6O11 catalyst demonstrated exceptional long-term stability, operating continuously for more than one month. These findings underscore the potential of Pr6O11-supported Ru catalysts for advancing efficient and durable ammonia synthesis.