Continuous supercritical solvothermal preparation of nanostructured ceria-zirconia as supports for dry methane reforming catalysts

The nanostructured Ce_xZr_1-xO₂ systems (0 ≤ x ≤ 0.75) were prepared combining alkoxide and nitrate precursors in an ethanol/water mixture by the continuous supercritical solvothermal sol-gel like synthesis. They were subsequently used as supports for nickel impregnation (10 wt.%) to obtain catalysts for dry reforming of methane (DRM) reaction. A reference Ce_xZr_1-xO₂ (x = 0.50) system prepared via conventional coprecipitation method was used as a support for nickel impregnation in the comparative study of the nanostructured materials’ catalytic potential. The morphological and structural properties of the prepared nanostructured supports and Ni-containing catalysts were investigated by numerous techniques as XRD, Raman spectroscopy, SEM, TEM, EDS, chemisorption and others. The conditions of DRM reaction were chosen in order to compare the activity, the stability as well as the selectivity of coke formation in the presence of the prepared catalytic materials. It was found that the industrial catalyst leads to heavy coking in the chosen conditions with a rapid loss of activity. While the nanostructured Ce_xZr_1-xO₂ (0 ≤ x ≤ 0.75) materials are found to be promising supports for Ni dispersion and coke control in DRM. In this study the nanostructured Ce_0.50Zr_0.50O₂ material impregnated with nickel shown the highest TOF and the smallest selectivity of coke formation in DRM among other nanostructured materials. The continuous supercritical solvothermal method allows to prepare nanostructured mixed oxide materials that could be promising supports for different active metals dispersion and for coke control in the reactions where coking may be abundant.