Unusual redox dynamics of Nb in the perovskite LaNbxNi1-XO3 and its impact on the dry catalytic reforming of methane

• Nb embodied into B position of the perovskite is in an unusual oxidation state (+4). • Nb oxidation during DRM suggests Ni nanoparticle charge redistribution. • The nickel decoration by Nb 2 O 5 could explain the Nb reduction during etching. • Nb confer a high resistance to Ni nanoparticles against carbon deposition. This study investigates the potential of Nb doping in Ni-based perovskites as a precursor for dry reforming of methane (DRM) applications. X-ray diffraction results indicate that Nb solubility in the LaNiO 3 perovskite structure can be up to 25 % of B-sites. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis suggests that the Nb incorporated into the perovskite adopts an unusual oxidation state (+4). The reducibility of Ni on this catalyst is influenced by both factors, which, in turn, affect its activity and catalytic stability during the DRM reaction. The duration of the reduction stage plays a crucial role, with an optimal reduction time identified: shorter reduction times result in lower catalytic activity but higher stability, while longer reduction times lead to higher catalytic activity but reduced stability. Carbon deposition on the surface of Ni nanoparticles is more pronounced in Nb-doped samples.