One-Step Synthesis of Highly Active and Stable Ni-ZrOx for Dry Reforming of Methane

A series of Ni-Zr catalysts with different Ni loadings were prepared by a novel one-step urea hydrolysis method and compared to the 10Ni/ZrO2 catalyst prepared by the ethanol impregnation method. The catalysts were tested in dry reforming of methane (DRM) at 750 degrees C with a mixed flow of CH4/CO2/Ar = 10:10:80 and GHSV = 24,000 h(-)(1). The materials were characterized by means of N-2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction by H-2, temperature-programmed desorption of CO2, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis coupled with mass spectrometry. 10Ni-Zr and 15Ni-Zr catalysts prepared by the one-step method exhibited higher activity, long-run stability, and selectivity of H-2/CO compared to 10Ni/ZrO2 catalysts. This could be ascribed to the smaller Ni crystallite size, increased specific surface area, and enhanced weak- and medium-strength basic sites over reduced 10Ni-Zr and 15Ni-Zr catalysts. The 10Ni-Zr and 15Ni-Zr catalysts demonstrated the suppression of metallic nickel sintering because of the formation of NiO-ZrO2 solid solution, leading to the stronger interaction between Ni and the ZrO2 matrix. Moreover, stability enhancement for these catalysts was possibly linked to a higher amount of adsorbed oxygen species, as confirmed by XPS.