Ni–Ce intermetallic phases in CeO2-supported nickel catalysts synthesized by γ-radiolysis

This work concerns the study of nickel clusters synthesized by radiation-induced reduction of Ni2+ ions previously adsorbed on ceria by ionic exchange in the aim to test their performance in catalytic hydrogenation. The nickel catalyst and CeO2 support were characterized by SEM coupled to X analysis, XRD, H2-adsorption and H-TPD. The catalyst prepared by irradiation presents high reducibility, dispersion and homogeneity of the metal phase. It is shown that the CeO2 support stores hydrogen during the radiolytic reduction of Ni ions and that the adsorbed hydrogen amounts strongly increase in the presence of nickel. The catalyst displays high catalytic performance in the benzene hydrogenation reaction (total conversion in a large and low temperature range). These properties are assigned to the high dispersion of nickel and to the promoter role of the support: actually, after the catalytic test, intermetallic nickel–cerium compounds (CeNi and CeNi2) are detected in the sample in addition to the Ni0 phase.