Promotional Effect of Iron for the Nitridation of Niobium Oxide to Niobium Nitride

Supported NbN catalysts were prepared under a N-2-H-2 gas stream by the addition of Fe species to Nb/SiO2. The nitriding process was monitored by in situ XAFS measurements. Fe K-edge XAFS and Nb K-edge in situ XAFS measurements revealed that Fe species in close proximity to niobium oxide can effectively induce nitridation of the niobium oxide with the nitriding rate being dependent upon the dispersion of Fe species. It was concluded that the dispersed Fe species close to niobium effectively assisted the nitridation of niobium oxide into NbN. The nitriding degree can be expressed by the coordination number of Nb-N.