Exsolution-like synthesis of Ni/(Nd2O3,CaO) nanocomposites from Nd2-xCaxNiO4 precursors for catalytic applications

A series of K2NiF4-like complex oxides Nd2-xCaxNiO4 (x ​= ​0–0.4) was obtained by the freeze drying synthesis method. Thermal decomposition of these precursors in H2 at 900 ​°C resulted in the formation of Ni/(Nd2O3,CaO) composites with different Nd2O3/CaO ratios. Their microstructure was similar to the products of the redox exsolution of perovskites: spherical 30 ​nm particles of Ni metal were allocated at the surface of dense agglomerates of Nd2O3 and CaO grains. The as-obtained composites demonstrated significant catalytic activity, selectivity, and stability in the reactions of dry reforming and partial oxidation of methane (DRM and POM, respectively) at T ​≥ ​800 ​°C. A surface of the oxide grains, obtained by the reduction of Nd2-xCaxNiO4, is coated with Ni nanoparticles that demonstrate a significant catalytic activity. [Display omitted] •Full thermal reduction of Nd2-xCaxNiO4 causes a formation of Ni metal, Nd2O3 and CaO.•A microstructure of as-obtained composites is similar to the products of exsolution.•A surface of (Nd2O3, CaO) agglomerates is coated with 30 ​nm spherical Ni particles.•High catalytic activity and selectivity in the reforming of methane was observed.