Preparation of Ni-ZrO₂ composites via mechanochemistry processes and their catalytic properties

Ni-ZrO₂ catalytic materials were prepared by the selective oxidation of Ni-ZrH₂ composite and amorphous Ni-Zr alloy powders synthesized by means of ball milling of NiZr₂ alloys under pressurized H2 and Ar atmospheres, respectively. Structural characterization was performed using X-ray diffraction and transmission electron microscopy. Ni-ZrH₂ composite and amorphous Ni-Zr alloy powders were oxidized at 550 °C and 800 °C, respectively. The size of Ni particles in Ni-ZrO₂-h ranged from 5 to 20 nm while that of Ni-ZrO₂-a were not separated obviously as fine particles. The mean sizes of the Ni particles in Ni-ZrO₂-h and Ni-ZrO₂-a obtained by XRD were about 16.9 nm and 28.4 nm, respectively. The methanol conversion ratio of Ni-ZrO₂-h was higher than that of the Ni-ZrO₂-a catalysts at all temperatures. Furthermore, it was found that Ni-ZrO₂-h has a highly endurable structure. It is believed that the enhanced catalytic properties of Ni-ZrO₂-h are due to its high surface area and separately dispersed Ni nanoparticles.