Dry reforming of methane towards CO-rich hydrogen production over robust supported Ni catalyst on hierarchically structured monoclinic zirconia nanosheets

Abstract

In this work, a series of monoclinic zirconia materials with diverse morphologies have been prepared by a facile NH4F-modulated hydrothermal method through changing molar ratio of NH4F to Zr atom from 0 to 2.8 (nF/Z). The supported Ni catalysts on various ZrO2 carriers (Ni//ZrO2-nF/Z) were prepared by previously reported l-Arginine ligand assisted incipient wetness impregnation (LA-IWI) method, and applied to dry (CO2) reforming of methane (DRM) reaction. The reaction results demonstrate that the catalytic performance of the supported Ni catalysts is strongly dependent on the morphologies of ZrO2 carriers affected by adjusting the nF/Z value. The supported Ni catalyst on the dahlia like hierarchical structure composed of monoclinic zirconia nanosheets (Ni/ZrO2-1.4) exhibits much superior catalytic performance including activity, selectivity and stability to the ones supported on the other morphologies supports. The structure–performance relationship of the as-synthesized supported Ni catalysts were explored by employing various characterization techniques including X-ray diffraction (XRD), N2 adsorption–desorption measurement, transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), CO chemisorption, CO2 temperature-programmed desorption (CO2-TPD), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). Results show that the catalytic activity of supported Ni catalysts is notably affected by their surface area, average Ni crystalline size, reducibility, Ni dispersity and basic properties, which is significantly dependent on the morphologies of ZrO2 carriers. Besides the higher activity and selectivity, the developed Ni/ZrO2-1.4 catalyst using the dahlia like hierarchical structure as a carrier exhibits unexpected higher coke- and Ni sintering-resistant stability to the supported Ni catalyst on ZrO2 nanoparticulate (Ni/ZrO2-0), which endows it to be a promising candidate for CO-rich hydrogen production and synthesis gas through dry reforming of methane.