Highly Active and Stable Lanthanum-doped Core-Shell-structured Ni@SiO2 Catalysts for the Partial Oxidation of Methane to Syngas

The nanostructures of silica-encapsulated NiO nanoparticles (NPs) doped with La, Ce, Ba, Co, Cu, and Fe were prepared and tested as catalysts for the partial oxidation of methane to syngas. Techniques that include TEM, XRD, Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), H-2 temperature-programmed reduction (TPR), and O-2 temperature-programmed oxidation (TPO) were employed to characterize the fresh and used catalysts to understand the structure-performance relationship. The La-doped Ni@SiO2 catalyst is superior to those doped with other elements. The effect of the reaction conditions on the catalyst performance over the best catalyst were also studied. The La2O3 species that were distributed uniformly throughout the NiO or Ni cores not only modify the core surfaces, but also enhance the resistance toward surface coking, which results in superior catalyst activity and durability.