Reactive ceramics of CeO2–MOx (M=Mn, Fe, Ni, Cu) for H2 generation by two-step water splitting using concentrated solar thermal energy

The possibility of producing chemical fuel (hydrogen) from the solar-thermal energy input using an isothermal cycling strategy is explored. The canonical thermochemical reactive oxide, ceria, is reduced under high temperature and inert sweep gas, and in the second step oxidized by H 2 O at the same temperature. The process takes advantage of the oxygen chemical potential difference between the inert sweep gas and high-temperature steam, the latter becoming more oxidizing with increasing temperature as a result of thermolysis. The isothermal operation relieves the need to achieve high solidstate heat recovery for high system efficiency, as is required in a conventional two-temperature process.Thermodynamic analysis underscores the importance of gas-phase heat recovery in the isothermal approach and suggests that attractive efficiencies may be practically achievable on the system level.However, with ceria as the reactive oxide, the isothermal approach is not viable at temperatures much below 1400 1C irrespective of heat recovery. Experimental investigations show that an isothermal cycle performed at 1500 1C can yield fuel at a rate of B9.2 ml g À1 h À1 , while providing exceptional system simplification relative to two-temperature cycling.

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“…[1][2][3][4][5][6][7] The reaction scheme, as written out explicitly for the case of H 2 production from H 2 …”

Section: Introductionmentioning

confidence: 99%

High-temperature isothermal chemical cycling for solar-driven fuel production

Hao

Yang

Haile

2013

Phys. Chem. Chem. Phys.

126

129

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“…In totality, these considerations suggest that ceria, which undergoes substantial oxygen stoichiometry changes without a change in crystal structure, has an extremely high melting temperature of approximately 2800 K, and displays high catalytic activity towards carbon-containing gases (Jin et al 1987;Trovarelli 1996;Murray et al 1999;Park et al 2000;Sharma et al 2000;Demoulin et al 2007), is an attractive material for thermochemical fuel production. Indeed, preliminary reports of the suitability of ceria for this technology have appeared in the recent literature (Abanades & Flamant 2006;Kaneko et al 2007Kaneko et al , 2008Kang et al 2007;Miller et al 2008;Kaneko & Tamaura 2009). Here, the reaction scheme (figure 1) involves a partial reduction at high temperature rather than a stoichiometric phase change.…”

Section: Introductionmentioning

confidence: 99%

A thermochemical study of ceria: exploiting an old material for new modes of energy conversion and CO ₂ mitigation

Chueh

Haile

2010

Phil. Trans. R. Soc. A.

388

399

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We present a comprehensive thermodynamic and kinetic analysis of the suitability of cerium oxide (ceria) for thermochemical fuel production. Both portions of the two-step cycle, (i) oxygen release from the oxide at 1773 and 1873 K under inert atmosphere, and (ii) hydrogen release upon hydrolysis at 1073 K, are examined theoretically as well as experimentally. We observe gravimetric fuel productivity that is in quantitative agreement with equilibrium, thermogravimetric studies of ceria. Despite the non-stoichiometric nature of the redox cycle, in which only a portion of the cerium atoms change their oxidation state, the fuel productivity of 8.5-11.8 ml of H 2 per gram of ceria is competitive with that of other solid-state thermochemical cycles currently under investigation. The fuel production rate, which is also highly attractive, at a rate of 4.6-6.2 ml of H 2 per minute per gram of ceria, is found to be limited by a surface-reaction step rather than by ambipolar bulk diffusion of oxygen through the solid ceria. An evaluation of the thermodynamic efficiency of the ceria-based thermochemical cycle suggests that, even in the absence of heat recovery, solar-to-fuel conversion efficiencies of 16 to 19 per cent can be achieved, assuming a suitable method for obtaining an inert atmosphere for the oxygen release step.

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“…(2)-(5)). The reactions (2)(3)(4)(5) can take place spontaneously with the following factors. Firstly, the Al-InZn alloy had À1.5 V potential [21,22] which was lower than À1.29 V of the H 2 O decomposition potential.…”

Section: Hydrogen Production For Fuel Cell Systemmentioning

confidence: 99%

“…Hydrogen production from two-step solar water splitting with metal oxides is one of the most promising alternatives with higher efficiencies and lower costs. Several redox materials (Fe 3 O 4 /FeO [3,4], ZnO/Zn [5], Mn 3 O 4 [6]) have been evaluated for such applications, but their high splitting temperature (above 800 C) limits their practical applications on board hydrogen production for vehicle fuel cell.…”

Section: Introductionmentioning

confidence: 99%

Feasibility study of hydrogen production for micro fuel cell from activated Al–In mixture in water

Fan

Sun

2010

Energy

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Reactive ceramics of CeO2–MOx (M=Mn, Fe, Ni, Cu) for H2 generation by two-step water splitting using concentrated solar thermal energy

Cited by 184 publications

References 23 publications

High-temperature isothermal chemical cycling for solar-driven fuel production

High-temperature isothermal chemical cycling for solar-driven fuel production

A thermochemical study of ceria: exploiting an old material for new modes of energy conversion and CO ₂ mitigation

Feasibility study of hydrogen production for micro fuel cell from activated Al–In mixture in water

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Reactive ceramics of CeO2–MOx (M=Mn, Fe, Ni, Cu) for H2 generation by two-step water splitting using concentrated solar thermal energy

Cited by 184 publications

References 23 publications

High-temperature isothermal chemical cycling for solar-driven fuel production

High-temperature isothermal chemical cycling for solar-driven fuel production

A thermochemical study of ceria: exploiting an old material for new modes of energy conversion and CO 2 mitigation

Feasibility study of hydrogen production for micro fuel cell from activated Al–In mixture in water

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Product

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A thermochemical study of ceria: exploiting an old material for new modes of energy conversion and CO ₂ mitigation