Structural and Catalytic Characterization of Radiation-Induced Ni/TiO2 Nanoparticles

Abstract

The radiolysis route is applied to synthesize nickel catalysts deposited on titanium dioxide. The TPR profile of radiation-induced Ni/TiO2 catalyst indicates a more complete reduction of the irradiated catalysts compared to the conventionally H2-reduced one. When tested in the benzene hydrogenation, the radiolytic Ni/TiO2 exhibits catalytic properties with higher efficiency than the H2-reduced catalyst. This observation is assigned to the presence of intermetallic Ni–Ti compounds (Ni2.66Ti1.33 and Ni3Ti) evidenced by XRD. In contrast, the calcined and H2-reduced catalyst contains predominantly the oxidized Ni5TiO7 phase, where the nickel is in strong interaction with the support. The TEM observations show highly dispersed nickel. When tested in the benzene hydrogenation reaction, the catalyst Ni/TiO2 prepared by gamma-irradiation exhibits catalytic properties (the turn-over frequency at total conversion is 33.5 molecules Bz Ni at −1 s−1 at 140 °C) with higher efficiency and at lower temperature than the H2-reduced catalyst. This observation is assigned to extremely dispersed nickel nanoparticles and to intermetallic Ni2.66Ti1.33 and Ni3Ti compounds evidenced by XRD.