The d band structure of Ru clusters in NH3 synthesis

NH3 is one of the most important chemical products but only made at 400-500 C and 150-300 bar conditions due to the stable N2 molecule. Here we have developed a Ru-CeO2 catalyst with high activity under 1-10 bar. Kinetic study reveals a H-assisted N2 dissociation mechanism, with a volcano-type activity dependence on the N2 activation barrier and the H2 adsorption strength. To validate such mechanism and volcano trends, we need to understand: 1) How the Ru d band centre determines the N2 activation behaviours; 2) Does the d band centre change along with reaction conditions; 3) How does N=NH* formed on Ru surface. Here we apply for an in situ Ru L3 edge vtc- RIXS study to follow the dynamics of Ru d band and identify Ru-N=NH under NH3 synthesis conditions. This study utilizes the uniqueness of the in situ tender RIXS capability at ID26. It is also a perfect synergy between in situ RIXS study and experimental kinetic models, which is the first of its kind for NH3 chemistry.