Synthesis, physicochemical and catalytic properties of Ni/PrCeZrO catalysts for water-gas shift reaction

Abstract Mixed nanocrystalline ceria-zirconia oxides doped with praseodymium containing 5, 7.5, 10, and 12.5 wt. % nickel were prepared by the incipient wetness impregnation of the oxide support. Complex physicochemical characterization by X-ray diffraction analysis, ultraviolet-visible diffuse reflectance spectroscopy, high resolution transmission electron microscopy and Fourier-transform infrared spectroscopy of adsorbed CO revealed that the nickelcontaining samples are comprised of a solid solution of praseodymium, cerium and zirconium oxides with the fluorite structure as well as nickel oxide particles with a size up to 100 nm. All prepared nanocomposite catalysts show a high catalytic activity in the water-gas shift reaction. The optimum content of nickel in the catalyst providing the maximum activity was found to be 10 wt. %. A high oxygen mobility in these catalysts estimated by the temperature-programmed oxygen isotope heteroexchange with C18O2 provides required coking stability. To eliminate local overheating of the catalyst and decrease the pressure drop in the reactor, as required for further up-scaling, the active component was supported on a metal plate made of Ni-Al foam alloy. At a fixed contact time, the same level of CO conversion with a fraction of the active component was achieved with an approximately 50 wt% loading on the support.