ESR observation of sulfur and oxygen species on cobalt-alumina and molybdenum-cobalt-alumina catalysts

When Co-g-Al2O3 and Co-Mo-g-Al2O3 catalysts are reduced and sulfided by H and H2S mixts., O and S species are present. The S species reacts with O to form a paramagnetic type of S, probably a short chain. The initial S species is absorbed H2S that is converted to S by a Claus reaction. The same ESR signals are obsd. on pure sulfided g-Al2O3. The O species is present on Co-Mo-g-Al2O3. O species is present on Co-Mo-g-Al2O3 catalysts after redn. with H and subsequent adsorption of O. At more elevated temps. (400 Deg instead of 200 Deg) the sulfiding treatment results in a more complex ESR signal, with a superposition of several S signals. [on SciFinder (R)]