Resumen del autor, extraído del trabajo. The Claus reaction is widely used to convert hydrogen sulfide stripped from acid gas or refinery off-gas streams to elemental sulfur. The performance of Claus catalyst depends on its morphological characteristics which are influenced by diffusion of reactants and products. · A scanning electron microscope (SEM) coupled with energy dispersive x-ray spectrometry (EDS) permits the observation and characterization of materials on surfaces at a microscopic scale. · An electron spectroscopy for chemical analysis (ESCA) is used to observe chemical deactivators on the catalyst by determining their oxidation state. · In this paper we will report the results of SEM and ESCA studies of the morphology and chemical analysis of the fresh and spent Claus catalysts before and after regeneration. The results indicated that the spent catalyst contained several distinct phases, indicating some contaminants. Also, the SEM micrographs showed coke lay-down on the surface which cause affect catalyst efficiency. · EDS X-ray analysis showed the presence of carbon, iron, and sulfur in alumina inanity. The elemental sulfur segregated towards the interior bulk, while carbon was found mostly near the surface. Iron deposition was also found near the surface of the spent catalyst. · ESCA analysis showed that coke is the major contaminant and some of the sulfur is present in the sulfate form in addition to elemental sulfur. · Examination of the regenerated catalyst showed removal of all contaminants by chemical treatment and nearly 90% by air-oxidation. · Results of this comprehensive study identified all contaminants in order to minimize catalyst deactivation.