Co-production of hydrogen and syngas from chemical looping water splitting coupled with decomposition of glycerol using Fe-Ce-Ni based oxygen carriers

Abstract

In this study, chemical looping water splitting (CLWS) coupled with glycerol decomposition to simultaneously produce hydrogen and syngas was proposed using the iron-cerium-nickel (Fe-Ce-Ni) based oxygen carriers (OCs). The OCs containing large amounts of iron were synthesized by the metal chelating sol–gel method and characterized by BET, XRD and TEM. During the fuel stage, the OCs of oxidation state were first reduced by the glycerol and reactive gases from catalytic decomposition of glycerol producing syngas. Afterward in the subsequent steam stage, the previously reduced OCs were re-oxidized by the steam to generate pure hydrogen, which was also named the steam iron process (SIP). The prepared Fe-Ce-Ni based OCs demonstrated the remarkable redox behavior, and exerted an important catalytic function of the partial oxidation and decomposition of glycerol at 750 ℃. The OCs with 100:10:3 of Fe-Ce-Ni molar ratio presented the best capability of oxygen transfer and the highest yields of hydrogen and syngas, reaching the water splitting hydrogen production of 11.79 mmol/g per cycle on average and guaranteeing the high conversion of glycerol and selectivity of syngas. This could be ascribed to the preferable dispersion of Ce and Ni nanoparticle on the OCs. The results also proved the effectiveness of Ce and Ni doping Fe based OCs by the improved metal chelating sol–gel method to develop the catalysts with high activity and stability for co-production of hydrogen and syngas from CLWS coupled with glycerol decomposition.