H2 production from a plasma-assisted chemical looping system from the partial oxidation of CH4 at mild temperatures

Zheng, Yaoyao

doi:10.1016/j.cej.2019.122197

Cited by 28 publications

(12 citation statements)

References 32 publications

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“…In this work, plasma-assisted reactive adsorption is employed in the context of a pioneering chemical looping-based approach to circumvent the limitations of plasma catalysis. Chemical looping assisted by plasma has recently been employed for chemistries other than CO 2 splitting, i.e., methane partial oxidation , and dry methane reforming. , In these references, dielectric barrier discharges (DBD) were coupled with reactive/catalytic materials that served as oxygen donors rather than oxygen scavengers as in this work. Finally, in ref , utilization of plasma solely as heat source in a chemical looping process for CO 2 reduction in the presence of steam was also theoretically studied …”

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confidence: 99%

Exceeding Equilibrium CO₂ Conversion by Plasma-Assisted Chemical Looping

et al. 2022

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We propose and demonstrate an integrated electrified plasma-assisted chemical looping (PACL) process that yields supra-equilibrium CO 2 conversions unattainable with conventional catalysis at temperatures ≪3000 K. CO 2 is first dissociated inside plasma into CO/O at supra-equilibrium conversions (up to 60%) at a bulk gas temperature of 773 K and a 403 kJ/mol energy cost. Supra-equilibrium CO 2 conversions (29% on average) are achieved at the reactor outlet by placing a nanostructured CeO 2 /Fe 2 O 3 oxygen scavenger, prereduced by H 2 plasma, downstream of the plasma zone, to capture produced oxygen species and suppress CO/O recombination. Without plasma-material synergy, such an average CO 2 conversion can only be attained at temperatures ≥ 2775 K, according to chemical equilibrium calculations. This concept of plasma-assisted chemical looping allows reaching 3-fold higher conversions than state-of-the-art plasma technologies.

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Exceeding Equilibrium CO₂ Conversion by Plasma-Assisted Chemical Looping

et al. 2022

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“…A similar mechanism for the Fe 2 O 3 /NiO oxygen carrier system was suggested, in which Fe 2 O 3 was able to transfer its lattice oxygen at a sufficient rate to the reduced Ni that the buildup of coke could be prevented, allowing the Ni to stay active while producing H 2 from methane. 38 A deep reduction of iron containing oxides will result in metallic Fe; metallic Fe is a known catalyst for the pyrolysis of methane. 4 , 6 , 15 , 34 The rapid increase in H 2 production was also found from a deeply reduced Fe 2 O 3 /Al 2 O 3 6 , 15 and also the perovskite La 0.8 Sr 0.2 FeO 3−δ .…”

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confidence: 99%

Understanding the Behavior of Dicalcium Ferrite (Ca₂Fe₂O₅) in Chemical Looping Syngas Production from CH₄

et al. 2022

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Previous work on calcium ferrites showed they were able to convert syngas to hydrogen via chemical looping. The mixture of iron and calcium and their oxides has different thermodynamic properties than iron oxide alone. Here, the use of methane, an abundant fuel, is investigated as the reductant in chemical looping syngas production. In contrast to syngas-fueled cycles, the looping materials became more active with cycling using methane as the fuel. When reduced by methane, the looping material often showed a significant induction period, indicating that products of reduction (in particular metallic Fe) acted as a catalyst for further reduction. The behavior in a thermogravimetric analyzer (TGA) and a fluidized bed was comparable, i.e., no degradation with cycling. The reduced C 2 F appeared to be easily reformed when oxidized with CO 2 , and there was little evidence of bulk phase segregation. The improved kinetics on cycling was likely due to the separation of metallic Fe onto the surface. Using hydrogen to partially reduce C 2 F promotes the catalytic pyrolysis of methane.

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“…At the same time, the mechanical integrity and strength were decreased due to the continuous migration of Fe ions. Zheng et al [240] compared the performance of iron oxide and nickel-impregnated iron oxide oxygenate carriers. The CH 4 conversion and H 2 yield of iron oxide alone were low, while the Ni-impregnated oxygen carriers had high H 2 yield, which may be due to the synergistic effect between nickel and iron.…”

Section: Iron Based Oxygen Carriermentioning

confidence: 99%

Chemical looping reforming: process fundamentals and oxygen carriers

et al. 2022

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Chemical looping reforming (CLR) provides a viable process intensification approach for clean and efficient syngas production from carbonaceous fuel with inherent gas–gas separation. The rational design of metal oxide-based oxygen carriers and the scale-up of associated CLR reactor systems play important roles in CLR process development. This review first introduces the concept and advantages of CLR as well as its historical development. The process fundamentals, including basic schemes, reaction stoichiometry, thermodynamics, kinetics and reactor system design, are reviewed. The integral approach for CLR process development is illustrated, showing that the design and compatibility of oxygen carriers and reactor systems are critical for CLR performance. The reaction principle during the reduction of oxygen carriers is discussed, followed by strategies for improving the redox reactivity and stability. We further review and discuss the latest exciting advances on this subject with the purpose of illustrating factors that govern fundamental mechanisms in the redox reaction chemistry of oxygen carriers and their design principles for sustained chemical looping reactor applications. It is expected that these new advances will inspire more effective oxygen carriers and efficient reactor systems for the development and deployment of various CLR processes.

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H2 production from a plasma-assisted chemical looping system from the partial oxidation of CH4 at mild temperatures

Cited by 28 publications

References 32 publications

Exceeding Equilibrium CO₂ Conversion by Plasma-Assisted Chemical Looping

Exceeding Equilibrium CO₂ Conversion by Plasma-Assisted Chemical Looping

Understanding the Behavior of Dicalcium Ferrite (Ca₂Fe₂O₅) in Chemical Looping Syngas Production from CH₄

Chemical looping reforming: process fundamentals and oxygen carriers

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H2 production from a plasma-assisted chemical looping system from the partial oxidation of CH4 at mild temperatures

Cited by 28 publications

References 32 publications

Exceeding Equilibrium CO2 Conversion by Plasma-Assisted Chemical Looping

Exceeding Equilibrium CO2 Conversion by Plasma-Assisted Chemical Looping

Understanding the Behavior of Dicalcium Ferrite (Ca2Fe2O5) in Chemical Looping Syngas Production from CH4

Chemical looping reforming: process fundamentals and oxygen carriers

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Product

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Exceeding Equilibrium CO₂ Conversion by Plasma-Assisted Chemical Looping

Exceeding Equilibrium CO₂ Conversion by Plasma-Assisted Chemical Looping

Understanding the Behavior of Dicalcium Ferrite (Ca₂Fe₂O₅) in Chemical Looping Syngas Production from CH₄