FERRITE-LOADED CERAMIC FOAM DEVICES PREPARED BY SPIN-COATING METHOD FOR A SOLAR TWO-STEP THERMOCHEMICAL CYCLE

摘要

A two-step water-splitting thermochemical cycle using redox working material of iron-based oxide (ferrite) particles has been developed for converting solar energy into hydrogen, The two-step thermochemical cycle for producing a solar hydrogen from water requires a development of a high temperature solar-specific receiver-reactor operating at 1000-1500°C.In the present work, ferrite-loaded ceramic foams with a high porosity (7 cells per linear inch) were prepared as a water splitting device by applying ferrite/zirconia particles on a MgO-partially stabilized Zirconia (MPSZ) ceramic foam. The water splitting foam device was prepared using a new method of spin coating. A spin coating method we newly employed that has advantages of shortening preparation period and reducing of the coating process in comparison to previous preparation method reported. The water-splitting foam devices, thus prepared, were examined on hydrogen productivity and reactivity through a two-step thermochemical cycle.NiFe_2O_4//m-ZrO_2/MPSZ and Fe3_O_4/c-YSZ/MPSZ foam devices were firstly tested for thermal reduction of ferrite using the laboratory scale receiver-reactor by a sun-simulator to simulate concentrated solar radiation. Subsequently, with another quartz reactor the light-irradiated device was reacted with steam by infrared furnace. As a result, it was possible toperform cyclic reactions over several times and to produce hydrogen through thermal-reduction at 1500°C and water-decomposition at 1100-1200°C.In further experiments, the NiFe_2O_4/m-ZrO_2/MPSZ foam device was successfully demonstrated in a windowed single reactor for cyclic hydrogen production by solar-simulated Xe-beam irradiation with input power of 1 kW. The NiFe_2O_/m-ZrO_2/MPSZ foam device produced hydrogen of 70-190umol per gram of device through 6 cycles and reached ferrite conversion of 60% at a maximum.