Chuayboon, Srirat

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Chuayboon, Srirat
Alternative Name
Chuayboon, S.
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Email
srirat.ch@kmitl.ac.th

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    High-Purity and Clean Syngas and Hydrogen Production From Two-Step CH4 Reforming and H2O Splitting Through Isothermal Ceria Redox Cycle Using Concentrated Sunlight
    (2020-07-17)
    Chuayboon, Srirat
    ;
    Abanades, Stéphane
    ;
    Rodat, Sylvain
    The thermochemical conversion of methane (CH<inf>4</inf>) and water (H<inf>2</inf>O) to syngas and hydrogen, via chemical looping using concentrated sunlight as a sustainable source of process heat, attracts considerable attention. It is likewise a means of storing intermittent solar energy into chemical fuels. In this study, solar chemical looping reforming of CH<inf>4</inf> and H<inf>2</inf>O splitting over non-stoichiometric ceria (CeO<inf>2</inf>/CeO<inf>2−δ</inf>) redox cycle were experimentally investigated in a volumetric solar reactor prototype. The cycle consists of (i) the endothermic partial oxidation of CH<inf>4</inf> and the simultaneous reduction of ceria and (ii) the subsequent exothermic splitting of H<inf>2</inf>O and the simultaneous oxidation of the reduced ceria under isothermal operation at ~1,000°C, enabling the elimination of sensible heat losses as compared to non-isothermal thermochemical cycles. Ceria-based reticulated porous ceramics with different sintering temperatures (1,000 and 1,400°C) were employed as oxygen carriers and tested with different methane flow rates (0.1–0.4 NL/min) and methane concentrations (50 and 100%). The impacts of operating conditions on the foam-averaged oxygen non-stoichiometry (reduction extent, δ), syngas yield, methane conversion, solar-to-fuel energy conversion efficiency as well as the effects of transient solar conditions were demonstrated and emphasized. As a result, clean syngas was successfully produced with H<inf>2</inf>/CO ratios approaching 2 during the first reduction step, while high-purity H<inf>2</inf> was subsequently generated during the oxidation step. Increasing methane flow rate and CH<inf>4</inf> concentration promoted syngas yields up to 8.51 mmol/g<inf>CeO<inf>2</inf></inf> and δ up to 0.38, at the expense of enhanced methane cracking reaction and reduced CH<inf>4</inf> conversion. Solar-to-fuel energy conversion efficiency, namely, the ratio of the calorific value of produced syngas to the total energy input (solar power and calorific value of converted methane), and CH<inf>4</inf> conversion were achieved in the range of 2.9–5.6% and 40.1–68.5%, respectively.
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    Chemical Looping CH4 Reforming Through Isothermal Two-Step Redox Cycling of SrFeO3 Oxygen Carrier in a Tubular Solar Reactor
    (2025-03-01)
    Abanades, Stéphane
    ;
    Wang, Xinhe
    ;
    Chuayboon, Srirat
    The chemical looping reforming of methane using an SrFeO<inf>3</inf> oxygen carrier to produce synthesis gas from solar energy was experimentally investigated and validated. High-temperature solar heat was used to provide the reaction enthalpy, and therefore the methane feedstock was entirely dedicated to producing syngas. The two-step isothermal process encompassed partial perovskite reduction with methane (partial oxidation of CH<inf>4</inf>) and exothermic oxidation of SrFeO<inf>3-δ</inf> with CO<inf>2</inf> or H<inf>2</inf>O splitting under the same operating temperature. The oxygen carrier material was shaped in the form of a reticulated porous foam structure for enhancing heat and mass transfer, and it was cycled in a solar-heated tubular reactor under different operating parameters (temperature: 950–1050 °C, methane mole fraction: 5–30%, and type of oxidant gas: H<inf>2</inf>O vs. CO<inf>2</inf>). This study aimed to assess the fuel production capacity of the two-step process and to demonstrate the potential of using strontium ferrite perovskite during solar cycling for the first time. The maximum H<inf>2</inf> and CO production rates during CH<inf>4</inf>-induced reduction were 70 and 25 mL/min at 1000 °C and 15% CH<inf>4</inf> mole fraction. The increase in both the cycle temperature and the methane mole fraction promoted the reduction step, thereby enhancing syngas yields up to 569 mL/g during reduction at 1000 °C under 30% CH<inf>4</inf> (778 mL/g including both cycle steps), and thus outperforming the performance of the benchmark ceria material. In contrast, the oxidation step was not significantly affected by the experimental conditions and the material’s redox performance was weakly dependent on the nature of the oxidizing gas. The syngas yield remained above 200 mL/g during the oxidation step either with H<inf>2</inf>O or CO<inf>2</inf>. Twelve successive redox cycles with stable patterns in the syngas production yields validated material stability. Combining concentrated solar energy and chemical looping reforming was shown to be a promising and sustainable pathway toward carbon-neutral solar fuels.