EELS Characterization of Ni-Mo Catalyst Synthesized by Mechanical Alloying

Raney-type Ni-Mo catalysts were produced by using mechanically alloyed Ni-Mo-Al powders, followed by an alkaline leaching process. Aluminum was removed in the later process to induce high catalytic activity. Results from X-ray diffraction analysis show no evidence of formation of new phases after the milling process. Apparently all aluminum is dissolved into Ni or Mo structure. The effect of the aluminum before and after the leaching process was analyzed by Electron Energy Loss Spectroscopy (EELS) technique. As changes in the L-2,L-3 white-lines intensities are associated with changes in d states occupancy for transition metals, properly normalized areas under L2,3 ionization edges were determined for the three stages of the process: Ni-Mo alloy before adding Al, Ni-Mo-Al and Ni-Mo-Al after the Al was removed by a leaching process. The analyses show that, as a consequence of the addition of At, some electrons migrate to Ni d-sites, showing that Al is dissolved in the original matrix and tends to restore to the original state after the leaching process.