Thermal behaviour in steam of a bituminous coal doped with alkali and alkaline earth metals

Abstract

Various alkali and alkaline earth metal compounds have been tested as catalysts for the gasification in steam, under dynamic conditions, of a bituminous coal from Bélmez (Cordoba, Spain). Most catalysts, at the lowest concentration studied, show a deactivation effect on the gasification reaction. Such an effect is sometimes enhanced with increasing catalyst concentration in the case of alkaline earth metal salts only. Amongst Na catalysts, NaOH gives rise to the largest increase in char reactivity with catalyst concentration at the smallest degree of conversion, while NaAc has proved to be the more active catalyst at the greatest degree of conversion. For K catalysts, the order of catalytic activity, whatever the degree of conversion, is K 2CO 3 > KOH > KAc > KCl at high catalyst concentrations. The alkaline earth metals, in general, do not catalyse the gasification reaction of this coal. Either Na or K are the best catalysts, depending on the composition of the catalyst.