摘要
The development of efficient and stable Ru catalysts is crucial for synthesis of decarbonized NH 3 . Herein, a series of γ-Al 2 O 3 -supported Cs-promoted Ru catalysts were prepared, among which a 1.5Cs-Ru/γ-Al 2 O 3 catalyst with a Cs/Ru molar ratio of 1.5 and a Ru size of ~2 nm exhibited high NH 3 synthesis rates (6.9–30 mmol g cat –1 h –1 ) at ~400 °C and 1 MPa. We unraveled that the surface acidity/basicity could be changed, and new active sites could be generated at the interfaces between the Ru particles and the CsOH-Cs 0 species by tuning the Cs/Ru molar ratio. Among the active sites, Cs 0 (minor), which transferred electrons to Ru, was present at the boundaries of the Ru particles and CsOH (major), which attracted the dissociative hydrogen atoms from the metallic Ru surfaces via a spillover effect and changed the surface acidity/basicity. This facilitated the adsorption/desorption of reactant species, thus promoting NH 3 synthesis.