X‐Ray Photoelectron Spectroscopy of Sulfur Containing Ni/SiO₂ Catalysts

Attempts were made to regenerate two Ni/SiO₂ catalysts which were exposed to sulfur‐containing compounds. Attempted regeneration was by oxidation followed by reduction. The amount of sulfur present after these treatments was followed by chemical analysis and X‐ray photoelectron spectroscopy. Oxidation and reduction was successful in removing a large part of the sulfur but catalytic activity for benzene hydrogenation could not be restored. The XPS data indicate that the small amounts of sulfur which remained after treatment in hydrogen were located largely in the bulk rather than at the surface of the nickel particles.