Understanding Ni-hydroxyapatites reactivity in CO2 methanation by operando XAS

Hydroxyapatites (Ca10(PO4)6(OH)2, HAp) are versatile materials that can be easily functionalized by substituting Ca2+ with metal ions of the same charge and similar ionic radius. The substitution of the Ca2+ by Ni2+ ions is particularly interesting, due to the versatility of Ni in many different applicative fields, including heterogeneous catalysis. Driven by encouraging laboratory results, we propose to study, by combined operando XAS and PXRD, Ni-HAp with different Ni loading during the CO2 methanation reaction. The experiment will clarify the changes in Ni speciation during the reaction and offer a molecular-level understanding of the mechanism behind Ni nanoparticle formation during catalyst pre-treatment in H₂.