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

Author(s):  
Hiroshi Kaneko ◽  
Hideyuki Ishihara ◽  
Takao Miura ◽  
Hiromitsu Nakajima ◽  
Noriko Hasegawa ◽  
...  

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.

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Hui Hong ◽  
Qibin Liu ◽  
Hongguang Jin

In this paper, a novel approach of middle-temperature solar hydrogen production using methanol steam reforming is proposed. It can be carried out at around 200–300°C, much lower than the temperatures of other solar thermochemical hydrogen production. For the realization of the proposed solar hydrogen production, solar experiments are investigated in a modified 5 kW solar receiver/reactor with one-tracking parabolic trough concentrators. The feature of significantly upgrading the energy level from lower-grade solar thermal energy to higher-grade chemical energy is experimentally identified. The interaction between the hydrogen yield and the energy-level upgrade of solar thermal energy is clarified. Also, this kind of solar hydrogen production is experimentally compared with methanol decomposition. The preliminarily economic evaluation of the hydrogen production is identified. As a result, in the solar-driven steam reforming, the thermochemical efficiency of solar thermal energy converted into chemical energy reached up to 40–50% under a mean solar flux of 550–700 W/m2, and exceeding 90% of hydrogen production is achieved, with about 70% higher than that of methanol decomposition. The thermochemical performance of solar-driven methanol steam reforming experimentally examined at around 200–300°C for hydrogen production may be competitive with conventional methane reforming. The promising results obtained here indicate that the proposed solar hydrogen production may provide the possibility of a synergetic process of both high production of hydrogen and effective utilization of solar thermal energy at around 200–300°C.


2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Hideyuki Ishihara ◽  
Hiroshi Kaneko ◽  
Noriko Hasegawa ◽  
Yutaka Tamaura

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.


Author(s):  
Tatsuya Kodama ◽  
Yoshiyasu Kondoh ◽  
Atsushi Kiyama ◽  
Ken-Ich Shimizu

Two different routes of solar thermochemical hydrogen production are reviewed. One is two-step water splitting cycle by using a metal-oxide redox pair. The first step is based on the thermal reduction of metal oxide, which is a highly endothermic process driven by concentrated solar thermal energy. The second step involves water decomposition with the thermally-reduced metal oxide. The first thermal reduction process requires very-high temperatures, which may be realized in sun-belt regions. Another hydrogen production route is solar reforming of natural gas (methane), which can convert methane to hydrogen via calorie-upgrading by using concentrated solar thermal energy. Solar reforming is currently the most advanced solar thermochemical process in sun belt. There is also possibility for the solar reforming to be applied for worldwide solar concentrating facilities where direct insolation is weaker than that in sun belt. Our experimental studies to improve the relevant catalytic technologies are shown and discussed.


Energy ◽  
2007 ◽  
Vol 32 (5) ◽  
pp. 656-663 ◽  
Author(s):  
H KANEKO ◽  
T MIURA ◽  
H ISHIHARA ◽  
S TAKU ◽  
T YOKOYAMA ◽  
...  

RSC Advances ◽  
2020 ◽  
Vol 10 (21) ◽  
pp. 12582-12597 ◽  
Author(s):  
Enkhbayar Shagdar ◽  
Bachirou Guene Lougou ◽  
Yong Shuai ◽  
Enkhjin Ganbold ◽  
Ogugua Paul Chinonso ◽  
...  

Integrating solar thermal energy into conventional SRM technology is a promising approach for low-carbon hydrogen production based on fossil fuel in near and midterm.


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