Effect of Ce3+ ions exchanged in NiX zeolites on the location and reducibility of Ni2+ ions and on the stabilization of a highly dispersed metallic nickel
Abstract
Highly dispersed nickel particles, with diameters ranging from 0.7 to 3 nm, can be obtained by hydrogen reduction of Ni2+ ions exchanged in X zeolites, in the presence of Ce3+ ions. Samples with various Ce3+/Ni2+ ratios have been studied.
The structure and surface properties of the solids were investigated by X-ray diffraction and e.p.r. The particle size was determined by magnetic methods.
It is shown that the Ce3+/Ni2+ ratio influences the initial location of the Ni2+ ions in the different cationic sites and the redox properties of the zeolite.
The effect of Ce3+ ions on the obtention of highly dispersed metallic nickel is discussed in terms of strong electrostatic field and electron-donor properties associated with Ce3+ ions.