(506d) H2 Generation From Thermochemical Water-Splitting Using Sol-Gel Synthesized Ferrites (MxFeyOz, M = Ni, Zn, Sn, Co, Mn, Ce)

H2 is a green fuel with the energy density of 143 MJ/kg, which is significantly higher than the commonly used fossil fuels. Industrially, H2 is generally produced by steam reforming of methane; however, this technology leads to significant generation of CO2. One of the green ways of producing H2 is by thermochemical water-splitting reaction, which utilizes mixed valence metal oxides (MO)-based redox reactions for the H2 generation. This technology relies on the two-step cycling process, where the first step involves the H2 generation from water-splitting reaction using ferrites at lower temperatures and the second step corresponds to the regeneration of the reacted ferrites at elevated temperatures. In this investigation, ferrites with the composition of MxFeyOz (M = Ni, Zn, Sn, Co, Mn, Ce) were synthesized using sol-gel technique. As-synthesized gels were aged for 24 h and heated rapidly in a muffle furnace or tubular furnace at 600?1000oC in air/N2 environment and quenched. The calcined powder thus obtained was characterized using powder X-ray diffraction, BET surface area analyzer and scanning electron microscopy (SEM). The ferrite powder was placed in a packed bed reactor and water-splitting reaction was performed at different temperatures. After water-splitting reaction, the material was regenerated at 900oC and reused for subsequent water-splitting reaction. Figure 1 shows transient H2 generation profiles obtained in two thermochemical water-splitting cycles at 700oC using NiFe2O4 and Sn0.2Fe2.8O4 materials. Several thermochemical cycles were performed at various experimental conditions to determine the water-splitting and regeneration ability of different ferrites. The effects of water-splitting reaction temperature and concentration of water in the feed stream on H2 generation were investigated. Ferrite conversion is being analyzed using shrinking core model. Synthesis methods, characterization, transient H2 profiles obtained at various experimental conditions and water-splitting reaction kinetics will be presented.