Rotary-Type Solar Reactor for Solar Hydrogen Production with Two-step Water Splitting Process

2007 ◽  
Vol 21 (4) ◽  
pp. 2287-2293 ◽  
Author(s):  
Hiroshi Kaneko ◽  
Takao Miura ◽  
Akinori Fuse ◽  
Hideyuki Ishihara ◽  
Shunpei Taku ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
Solar Hydrogen ◽  
Solar Reactor ◽  
Solar Hydrogen Production ◽  
Splitting Process ◽  
Rotary Type

Hydrogen Production Through Two-Step Water Splitting Using YSZ (Ni,Fe) System for Solar Hydrogen Production

Solar Energy ◽  
2005 ◽  
Author(s):  
Hideyuki Ishihara ◽  
Hiroshi Kaneko ◽  
Tsutomu Yokoyama ◽  
Akinori Fuse ◽  
Noriko Hasegawa ◽  
...  
Keyword(s):  
Solid Solution ◽  
Hydrogen Production ◽  
Water Splitting ◽  
Gas Flow ◽  
Molar Ratio ◽  
Iron Ions ◽  
Solar Hydrogen ◽  
Solar Hydrogen Production ◽  
Ar Gas ◽  
Splitting Process

The two-step water splitting with the solid solution of YSZ (Yttrium stabilized Zirconia) and Ni-ferrite (NiFe2O4) was studied for solar hydrogen production. The sample of YSZ/Ni-ferrite solid solution was prepared by calcination of the mixture of the YSZ balls and Ni-ferrite (NiFe2O4) powder. The two-step water splitting process composed of O2-releasing reaction (T = 1773K) in Ar gas flow and H2-generation reaction (T = 1473K) in Ar gas and steam flow with the YSZ/Ni-ferrite solid solution were repeated ten times, and the molar ratio of the released O2 gas and the generated H2 gas was nearly equal to 1:2 in each cycle, indicating that the two-step water splitting process proceeded stoichiometrically. The lattice constants of the YSZ/Ni-ferrite solid solution products after each step of the water splitting process were varied, therefore it was assumed that the oxidation and reduction of the iron ions proceeded in the YSZ phase. It is confirmed that the YSZ/Ni-ferrite was the solid solution and reactive ceramics of high thermal stability. The contents of iron ions determined by the atomic absorption spectroscopy indicated that the YSZ/Ni-ferrite solid solution heated at 1773K contained the only 36% of iron loaded initially. The generated O2 gas was 42% of the theoretical yield. These suggest that YSZ/Ni-ferrite solid solution is more effective reactive ceramics which has the ability to split water with concentrated solar heat than Ni-ferrite.

Two-Step Water Splitting Process With Solid Solution of YSZ and Ni-Ferrite for Solar Hydrogen Production (ISEC 2005-76151)

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Hideyuki Ishihara ◽  
Hiroshi Kaneko ◽  
Noriko Hasegawa ◽  
Yutaka Tamaura
Keyword(s):  
Thermal Stability ◽  
Solid Solution ◽  
Hydrogen Production ◽  
Water Splitting ◽  
Solar Hydrogen ◽  
H2 Generation ◽  
Concentrated Solar Energy ◽  
Solar Hydrogen Production ◽  
Gas Volume ◽  
Splitting Process

Ni-ferrite (NiFe2O4) is a promising reactive ceramics of the ferrite for the solar hydrogen production by a two-step water splitting process using concentrated solar energy. However, it should be pretreated before H2-generation reaction by grinding the Ni-ferrite sintered after the O2-releasing reaction to make a fine powder. If the Ni-ferrite and yttria stabilized zirconia (YSZ) form a solid solution between these oxides (YSZ∕NiFe2O4 solid solution=YSZ(Ni,Fe)), it is expected that the two-step water splitting process with the Ni-ferrite system can proceed without treatment of the reduced product because of the high thermal stability of the YSZ∕NiFe2O4 solid solution. The YSZ∕NiFe2O4 solid solution was prepared by calcination of the mixture of the YSZ balls and NiFe2O4 powder at T=1823K for 1h, and its reactivity and thermal stability were examined for the two-step water splitting process. During the ten times repetition of the two-step water splitting reaction (T=1773K for O2-releasing, and 1473K for H2-generation) with the YSZ∕NiFe2O4 solid solution using infrared imaging furnace, the reactivity for O2-releasing and H2-generation was kept constant. The molar ratio of the released O2 gas volume (the average O2 gas, 1.9cm3∕g) and the generated H2 gas volume (the average H2 gas, 3.8cm3∕g) was nearly 1:2, indicating that the water decomposition process via two steps proceeds. The X-ray diffractometry (XRD) measurement showed that the YSZ(Ni,Fe) keeps the YSZ phase structure during the ten times repetition of the two-step water splitting process. The successive H2 gas production by the two-step water splitting process was performed (ten times repetition of the two-step water splitting process). From comparative study on the reactivity and the thermal stability for the two-step water splitting reaction among the YSZ∕NiFe2O4 solid solution, NiFe2O4 and ZnFe2O4, it is concluded that the YSZ∕NiFe2O4 solid solution is superior to the others.

H2 Generation by Two-Step Water Splitting With CeO2-MOx Using Concentrated Solar Thermal Energy

Solar Energy ◽  
2006 ◽  
Author(s):  
Hiroshi Kaneko ◽  
Hideyuki Ishihara ◽  
Takao Miura ◽  
Hiromitsu Nakajima ◽  
Noriko Hasegawa ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
Thermal Energy ◽  
Infrared Imaging ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Solar Simulator ◽  
Solar Hydrogen ◽  
H2 Generation ◽  
Solar Hydrogen Production

CeO2-MOx (M = Mn, Fe, Ni, Cu) reactive ceramics, having high melting points and high conductivities of O2−, were synthesized with the combustion method from their nitrates for solar hydrogen production. The prepared CeO2-MOx samples were solid solutions between CeO2 and MOx with the fluorite structure through XRD. Two-step water splitting reactions with CeO2-MOx reactive ceramics proceeded at 1573–1773K for the O2 releasing step and at 1273K for the H2 generation step by irradiation of infrared imaging furnace as a solar simulator. The amounts of O2 evolved in the O2 releasing reaction with CeO2-MOx and CeO2 systems increased with the increase of the reaction temperature. The amounts of H2 evolved in the H2 generation reaction with CeO2-MOx systems except for M = Cu were more than that of CeO2 system after the O2 releasing reaction at the temperatures of 1673 and 1773K. The largest amount of H2 was generated with CeO2-NiO after the O2 releasing reaction at 1573, 1673 and 1773K. The O2 releasing reaction at 1673K and H2 generation reaction at 1273K with CeO2-Fe2O3 were repeated four times with the evolving of O2 (1.3cm3/g-sample) and H2 (2.3cm3/g-sample) gases, respectively. The possibility of solar hydrogen production with CeO2-MOx (M = Mn, Fe, Ni) reactive ceramics system by using concentrated solar thermal energy was suggested.

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