Catalysis by alkali and alkaline earth metals of the gasification in CO 2 and in steam of chars from a bituminous coal with high inorganic matter content

Abstract

Several compounds of alkali and alkaline earth metals have been tested as catalysts for the gasification in carbon dioxide and in steam, under isothermic conditions, of chars from a bituminous coal with high inorganic matter content from Peñarroya (Córdoba, Spain). The results show that some catalysts, and especially the alkali metal hydroxides, produce a deactivation for char gasification in both atmospheres. Such a deactivating effect is only observed when very low catalyst concentration is used. Char reactivity varies with the catalyst concentration and depends on the catalyst type (alkali or alkaline earth metal compound). NaAc and NaOH bring about a large increase of char reactivity at higher catalyst concentrations. By contrast, CaAc 2 and CaCl 2 produce a more substantial increase of char reactivity at comparatively lower catalyst concentrations. At high catalyst concentration and gasification temperature, the order of catalytic activity found is CaCl 2 > NaAc > CaAc 2> NaOH > NaCl for gasification in steam and NaAc > NaOH > CaAc 2 > CaCl 2 > NaCl for gasification in carbon dioxide.