Influence of La(Ni,Fe,Re)O3 structure on its solid-phase crystallization into methane reforming catalysts

Brian Rosen, Materials Science and Engineering, Tel Aviv University, Ramat Aviv, Israel

The exploitation and control of structure in methane reforming catalysts remains a significant challenge to chemists and engineers worldwide. Currently, methane conversion catalysts are limited by their ability to resist surface carbon accumulation, sintering, and unwanted oxidation. These mechanisms are detrimental to catalyst lifetime and have prevented processes such as methane dry reforming from large scale industrialization. All of these deactivation mechanisms are highly influenced by the strength of the interaction between the active catalyst and its support, as well as the size and shape of the active catalyst phase. Solid-phase crystallization of well-ordered materials has been proposed to be an effective single-step method for forming catalysts with strong metal-support interactions. So far, investigation of this method has largely focused on bulk and supported Perovskites (ABO3) as the parent phase and the influence of non-stoichiometric formulations on the ability to exsolve metal (B-atom) crystals. These studies revealed that A-site deficiencies in conjunction with oxygen vacancies beyond a limiting concentration (δ,lim) destabilized the Perovskite structure sufficiently such that the B-atom would exsolve in order to maintain the original stoichiometry. This work investigates how shape-control and atomic substitutions of the parent LaNiO3 Perovskite nanoparticle can be exploited to imbue a favorable spatial distribution of exsolved Ni and Ni-alloy crystals, a strong catalyst-support interaction, and provide for long-term coke-free catalytic methane oxidation. Here, we also discuss how depletion effects within the parent Perovskite and the pathway taken during crystallization influences the final material enabling sustainable and intelligent catalyst design.