| Abstract
| - New technologies for power generation demand the development of regenerable sorbentsfor hot coal gas desulfurization down to very low levels of H2S. Unfortunately, long-termtests in different reactors show that usual regenerable sorbents exhibit such efficiency decayand degradation of mechanical properties that their use is impractical in the current stateof the art. In a previous study, some long-term tests in a fixed bed reactor have shown thatZn- or Cu-doped manganese oxide sorbents exhibit good performance. The highlightingfeatures in the behavior of these sorbents are a substantial change in sulfidation reactivityas they are doped with zinc or copper oxides and a pronounced efficiency increase duringthe first 1−5 sulfidation−regeneration cycles. To understand this apparent behavior, adetailed characterization study of fresh, sulfided, and regenerated sorbents has been carriedout using X-ray diffraction and transmission electron microscopy techniques. This studyshows that the structure and degree of dispersion of the active phases in the fresh andregenerated sorbents and those of sulfides in the sulfided sorbents are highly dependent onthe chemical nature of the dopant used. Zn enhances the formation of mixed oxide or sulfidespecies, while Cu increases mostly the degree of dispersion. These structural and texturalchanges can be associated with the high sulfidation reactivity exhibited by the studiedmanganese-based sorbents.
|
