Ni/CeO2 catalysts prepared by aqueous hydrazine reduction

Abstract In this study 1–5%Ni catalysts supported on commercial CeO 2 were prepared by the chemical reduction in aqueous hydrazine. They were characterized by H 2 -TPR, H 2 -adsorption, H 2 -TPD, XRD, TEM, STEM, EDS and X-mapping techniques. We obtained chestnut bur-like nickel morphology not reported in the literature for Ni/CeO 2 catalysts. These structures consisted in a central ball of 0.3 μm composed of smaller crystallites with mean size of 20–40 nm and surrounded by needles of 0.1–0.3 μm. Small spherical particles (≤2 nm) were also observed. Nickel was found in a highly reduced state and, in contrast to SiO 2 , the ceria support highly preserves the nickel from partial oxidation in air atmosphere. Noticeably, reduction of ceria by hydrazine occurred in the aqueous media at 353 K whereas it starts only at 640 K in gaseous hydrogen atmosphere.