Fe- and Co-doped lanthanum oxides catalysts for ammonia decomposition: Structure and catalytic performances

In this paper, a series of Fe- and Co-doped lanthanum (hydr)oxides catalysts were prepared by a simple coprecipitation-hydrothermal method. The as-prepared catalysts were characterized with various techniques including powder X-ray diffraction (XRD), N 2 adsorption/desorption, inductively coupled plasma (ICP) and transmission electron microscopy (TEM). The Fe-based catalysts exhibited consecutive phase changes of amorphous FeO x →FeLaO 3 →Fe 2 N under different stages (as-prepared→calcination→ammonia decomposition reaction); as for Co-based catalysts, the phase transformation followed a sequence of Co(OH) 2 → Co 3 O 4 →metallic Co. It was revealed that Fe 2 N and metallic Co were most probably the active crystalline phase respectively for Fe- and Co-based catalysts in the decomposition of ammonia.