New Solar Water-Splitting Reactor With Ferrite Particles in an Internally Circulating Fluidized Bed

The thermal reduction of metal oxides as part of a thermochemical two-step water-splitting cycle requires the development of a high-temperature solar reactor operating at 1000-1500 degrees C. Direct solar energy absorption by metal-oxide particles provides direct efficient heat transfer to the reaction site. This paper describes the experimental results of a windowed small reactor using an internally circulating fluidized bed of reacting metal-oxide particles under direct solar-simulated Xe-beam irradiation. Concentrated Xe-beam irradiation directly heats the internally circulating fluidized bed of metal-oxide particles. NiFe(2)O(4)/m-ZrO(2) (Ni-ferrite on zirconia support) particles are loaded as the working redox material and are thermally reduced by concentrated Xe-beam irradiation. In a separate step, the thermally reduced sample is oxidized back to Ni-ferrite with steam at 1000 degrees C. The conversion efficiency of ferrite reached 44% (+/- 1.0%), which was achieved using the reactor at 1 kW of incident Xe lamp power. The effects of preheating temperature and NiFe(2)O(4)/m-ZrO(2) particle size on the performance of the reactor for thermal reduction using an internally circulating fluidized bed were evaluated.