Abstract
This work is aimed at characterizing reduced Ni/Al2O3 catalysts, when a commercial -Al2O3 support is modified by sodium ions. The effect of Na and Ni treatment on the acid-base properties of -Al2O3 has been studied with IR, by adsorption of probe molecules (benzene, pyridine, tert-butyl cyanide and pyrrole). The Na-treatment decreases the number of Lewis acid sites and strengthens the basic sites on the alumina surface. The distribution of Na incorporated in increasing quantities onto -Al2O3 and its influence on the dispersion of the Ni subsequently impregnated on the modified support have been studied by XPS. The addition of a minute amount of Na diminishes the Na dispersion by neutralizing special exchange sites. For higher concentration 3, Na improves the Ni dispersion. At contents corresponding to H 4 atom nm-2, sodium is atomically dispersed on the surface; it takes a more “bulk-like” configuration at higher concentrations. The reduction process does not affect significantly the state of dispersion of nickel.
Published Version
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