Researchers tracked the step-by-step breakdown of lanthanum nickelate during reduction and methane dry reforming, according to a study published in Nature Communications. Using in situ electron microscopy, the team identified the intermediate phases that emerge before the catalyst fully decomposes.
The study combined dark-field and bright-field imaging with secondary-electron contrast and operando electronic structure measurements. By observing the material across reduced and bar-level reactant partial pressures, the authors localized the paired formation of nickel-oxygen particles and La2NiO4. These intermediate structures appear during dry reforming operations before the material breaks down completely into metallic nickel and La2O3.
Gas conditions altered how the particles behaved. Nickel particles formed in vacuum or dry reforming gas mixtures underwent brief surface oxidation driven by lattice oxygen, while hydrogen reduction produced highly dynamic metallic particles. At elevated temperatures, catalyst behavior was governed by simultaneous nickel formation, transitions from LaNiO3 to La2NiO4, Ostwald ripening, particle fragmentation, and agglomeration.
Exposing reduction-formed nickel to methane dry reforming mixtures triggered fast oxidation into sintering-resistant nickel oxide, showing size-dependent dissolution and agglomeration traits. Because carbon dioxide cannot directly oxidize nickel under these experimental conditions, the authors found that oxygen migration from the bulk perovskite material drives this performance-limiting nickel oxide formation.
Pengfei Cao and Christoph Malleier contributed equally to the research, collaborating across Forschungszentrum Jülich, the University of Innsbruck, RWTH Aachen University, Technische Universität Berlin, and Ruhr-University-Bochum. Funding came from the Austrian Science Fund, the German Research Foundation, and the German Federal Ministry of Research, Technology and Space.
