Catalytic steam gasification of sawdust char on K-based composite catalyst at high pressure and low temperature

Abstract

The effects of temperature, pressure, steam ratio and K-based composite catalysts on the pressurized steam gasification of sawdust char were studied and the physicochemical structure of composite catalysts was characterized in detail. The results indicated that steam promoted the production of hydrogen but suppressed that of CH4. The generation of CH4 required high pressure, low temperature and suitable steam atmosphere. The composite catalysts reduced the reaction temperature and increased the carbon conversion, theirs catalytic performance ranked in descending order was KCe > KCo > KFe > KNi, where KCe showed perfect catalytic performance, which mainly determined by the ability to activate carbon during pressurized steam gasification of char. KFe and KCo were more conducive to water-gas-shift reaction, while KNi had the better performance on gasification reaction. The transformation paths of the composite catalysts were as follows: Ce(NO3)3·6H2O → CeO2, Co(NO3)2·6H2O → CoO/Co3O4 → Co → CoO, Fe(NO3)3·9H2O → Fe2O3 → FeO → Fe3O4 and Ni(NO3)2·6H2O → NiO → Ni.