Stoichiometric studies of H2 generation reaction for H2O/Zn/Fe3O4 system

Tamaura, Yutaka; Kojima, Noboru; Hasegawa, Noriko; Inoue, Masafumi; Uehara, Reiko; Gokon, Nobuyuki; Kaneko, Hiroshi

doi:10.1016/s0360-3199(01)00039-8

Cited by 40 publications

(18 citation statements)

References 11 publications

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“…Mixed-metal ferrites that incorporate transition metals in the ferrite structure can be reduced at lower reduction temperatures and are being studied intensively. Such metals are Mn [10,11], Co [12,13], Ni [14,15] and Zn [16][17][18] and several comparative studies were performed [19,20]. Different approaches on solar receiver concepts, which use mixed ferrites [21][22][23][24][25][26][27][28][29][30], have been developed and already tested.…”

Section: Introductionmentioning

confidence: 99%

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Neises

Roeb

Schmücker

et al. 2009

Int. J. Energy Res.

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SUMMARYA two-step thermochemical cycle for solar hydrogen production using mixed iron oxides as the metal oxide redox system has been investigated. The ferrite is coated on a honeycomb structure, which serves as the absorber for solar irradiation and provides the surface for the chemical reaction. Coated honeycomb structures have already been tested in a solar receiver reactor in the solar furnace of DLR in Cologne with respect to their water splitting capability and their long-term stability. The concept of this new reactor design has proven feasible and constant hydrogen production during repeated cycles has been shown.For a further optimization of the process and in order to gain reliable performance predictions more information about the process especially concerning the kinetics of the oxidation and the reduction step are essential.To examine the hydrogen production during the water splitting step a test rig has been built up on a laboratory scale. In this test rig small coated honeycombs are heated by an electric furnace. The honeycomb is placed inside a tube reactor and can be flushed with water vapour or with an inert gas. A homogeneous temperature within the sample is reached and testing conditions are reproducible. Through analysis of the product gas the hydrogen production is monitored and a reaction rate describing the hydrogen production rate per gram ferrite can be formulated. Using this test set-up, SiC honeycombs coated with zinc ferrite have been tested. The influences of the temperature and the water concentration on the hydrogen production during the water splitting step have been investigated. An analysis of the ferrite conversion was performed using the Shrinking Core Model. A mathematical approach for the peak reaction rate at the beginning of the water splitting step was formulated and the activation energy was calculated from the experimental data. An activation energy of 110 kJ mol À1 was found.

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Section: Introductionmentioning

confidence: 99%

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Neises

Roeb

Schmücker

et al. 2009

Int. J. Energy Res.

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“…The biggest challenge faced in all previous studies is that the high temperatures needed to regenerate the deactivated catalyst after the water splitting step. The decomposition temperature of ZnO and Mn 3 O 4 are 2350 and 1810 K, respectively [8][9][10][11] . It is also the case with the H 2 O/ Nb 2 O 5 / NbO 2 system.…”

Section: Introductionmentioning

confidence: 99%

Studies on the preparation of active oxygen-deficient copper ferrite and its application for hydrogen production through thermal chemical water splitting

Zhang

et al. 2008

Sci. China Ser. B-Chem.

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Hydrogen generation through thermal chemical water splitting technology has recently received increasingly international interest in the nuclear hydrogen production field. Besides the main known sulfur-iodine (S-I) cycle developed by the General Atomics Company and the UT3 cycle (iron, calcium, and bromine) developed at the University of Tokyo, the thermal cycle based on metal oxide two-step water splitting methods is also receiving research and development attention worldwide. In this work, copper ferrite was prepared by the co-precipitation method and oxygen-deficient copper ferrite was synthesized through first and second calcination steps for the application of hydrogen production by a two-step water splitting process. The crystal structure, properties, chemical composition and δ were investigated in detail by utilizing X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), atomic absorption spectrometer (AAS), ultraviolet spectrophotometry (UV), gas chromatography (GC), and so on. The experimental two-step thermal chemical cycle reactor for hydrogen generation was designed and developed in this lab. The hydrogen generation process of water splitting through CuFe 2 O 4−δ and the cycle performance of copper ferrite regeneration were firstly studied and discussed.copper ferrite, oxygen deficient, thermal chemical water splitting, hydrogen production

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“…Mixtures of Fe 3 O 4 + Zn and Fe 3 O 4 + ZnO were investigated regarding their water-splitting ability. A mixture of Fe 3 O 4 and Zn was able to produce hydrogen at a temperature of 873 K, forming Zn-ferrites (Zn x Fe 3− x O 4 (0.2 ≤ x ≤ 1)) and ZnO [58]. Fe 3 O 4 mixed with ZnO was able to split water at 973–1073 K, forming a nonstoichiometric spinel product with lower zinc content than the stoichiometric ZnFe 2 O 4 [59].…”

Section: Metal Oxide-based Redox Materialsmentioning

confidence: 99%

Materials-Related Aspects of Thermochemical Water and Carbon Dioxide Splitting: A Review

et al. 2012

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Thermochemical multistep water- and CO2-splitting processes are promising options to face future energy problems. Particularly, the possible incorporation of solar power makes these processes sustainable and environmentally attractive since only water, CO2 and solar power are used; the concentrated solar energy is converted into storable and transportable fuels. One of the major barriers to technological success is the identification of suitable active materials like catalysts and redox materials exhibiting satisfactory durability, reactivity and efficiencies. Moreover, materials play an important role in the construction of key components and for the implementation in commercial solar plants. The most promising thermochemical water- and CO2-splitting processes are being described and discussed with respect to further development and future potential. The main materials-related challenges of those processes are being analyzed. Technical approaches and development progress in terms of solving them are addressed and assessed in this review.

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Stoichiometric studies of H2 generation reaction for H2O/Zn/Fe3O4 system

Cited by 40 publications

References 11 publications

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Studies on the preparation of active oxygen-deficient copper ferrite and its application for hydrogen production through thermal chemical water splitting

Materials-Related Aspects of Thermochemical Water and Carbon Dioxide Splitting: A Review

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