Scheelite-type alkali metal perrhenates supported Co-based catalysts for highly efficient ammonia synthesis

The development of highly efficient and stable non-precious metal catalysts under mild conditions is highly desirable for NH 3 synthesis. However, the competitive adsorption of N 2 and H 2 on the single site and strong NH 3 adsorption greatly hinder the catalytic efficiency of catalysts under mild conditions. Herein, we propose the use of responsive alkali metal perrhenates (AMReO 4 , AM = K, Na, or Cs) supports with scheelite-type structure that contains active Re metal and promoters to disperse cobalt (Co) species, constructing highly efficient catalysts by regulating the competitive reactant adsorption-activation pattern to a non-competitive mechanism. Our studies demonstrate that Co/KReO 4 catalyst shows excellent catalytic performance for NH 3 synthesis. Co and Re sites synergistically to promote the activation of N 2 molecules, while the adsorption and activation of H 2 primarily occur on Re sites of KReO 4 . The presence of Co species facilitates H-spillover that enables the migration of *H species from Re to Co sites, then cascade catalysis of hydrogen and dissociated nitrogen species to form NH 3 . Accordingly, the NH 3 synthesis rate of Co/KReO 4 (11.48 mmol NH3 g cat −1 h −1 ) is 3.2-fold higher than that of KReO 4 (3.58 mmol NH3 g cat −1 h −1 ) at 400 °C and 1 MPa. This work emphasizes the significance of employing reactive supports containing promoters and active metals, in collaboration with non-precious Co sites, to enhance NH 3 synthesis performance under mild conditions.