Production of hydrogen by steam oxidation of calcium ferrite reduced with various coals

Abstract

Production of H2 by steam oxidation was demonstrated with calcium ferrite (CaFe2O4) after coal gasification to produce CO with several types of coals. All coal types reacted with CaFe2O4 to produce CO. The reduced CaFe2O4 after the reaction with coal can also be oxidized with steam at 800 °C while producing of H2. Sub-bituminous coal and lignite coal had better reactivity with CaFe2O4 than the bituminous coal. A ten-cycle test conducted with Wyodak coal/CaFe2O4 at 800 °C showed stable production of H2 during oxidation with steam. A 25-cycle steam oxidation test conducted after reduction of CaFe2O4 with lignite coal also showed a very stable performance. Steam oxidation is sufficient for maintaining the cyclic reactions. A larger scale (2 kg batch) production of CaFe2O4 by wet granulation-tumbling method was successful. Steam oxidation was demonstrated with the large-scale batch of CaFe2O4 after reduction with Wyodak coal.