Performance and kinetics of iron-based oxygen carriers reduced by carbon monoxide for chemical looping combustion

Hua, Xiuning; Wang, Wei; Wang, Feng

doi:10.1007/s11783-015-0821-y

Cited by 13 publications

(6 citation statements)

References 26 publications

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“…During the last years, most of the research on kinetics of low-cost oxygen carriers for the iG-CLC process was focused on Febased materials. Most of the kinetic studies that can be found in literature on Fe-based oxygen carriers refer to synthetic materials (supported or unsupported Fe 2 O 3 ) [18][19][20][21][22][23][24][25][26]. Most of these studies consider the reduction from Fe 2 O 3 not only to Fe 3 O 4 , which would be the most interesting for iG-CLC purposes [27], but also the further reduction to FeO /Fe.…”

Section: Introductionmentioning

confidence: 99%

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Mendiara

Abad

Gayán

et al. 2019

Chemical Engineering Journal

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The in-situ Gasification Chemical Looping Combustion (iG-CLC) process allows combustion with inherent CO 2 capture. In this process, the oxygen for combustion is commonly supplied by a solid oxygen carrier based on a metal oxide thus avoiding direct contact between fuel and air. The oxygen carrier circulates between two reactors. In the fuel reactor, the fuel is oxidized to CO 2 and H 2 O while the oxygen carrier is reduced. In the air reactor, the reduced oxygen carrier is regenerated in air. Ilmenite has been widely used as a low-cost oxygen carrier for the iG-CLC process, and it can be taken as a reference material. Recently, the Tierga iron ore has been identified as a promising candidate for further scale-up of the process due to the higher combustion efficiency achieved compared to the results using 2 ilmenite. Modelling of the iG-CLC process with Tierga iron ore as oxygen carrier is a key step to determine the potential of this material. In order to model the iG-CLC process it is necessary to know the reactivity of both oxygen carrier and fuel used. In this paper, the kinetic determination for the reduction and oxidation reactions of the Tierga ore is presented.Reaction orders close to unity were obtained for the main reducing gases, i.e. H 2 , CO and CH 4 , as well as O 2 . The activation energy values obtained were 81.1±7, 76.1±6 and 257±14 kJ/mol for H 2 , CO and CH 4 , respectively. The activation energy for oxidation was determined as 18.4±05 kJ/mol. In addition, a simple method is used for a comparison of the performance of different oxygen carriers based on their kinetics.

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Section: Introductionmentioning

confidence: 99%

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Mendiara

Abad

Gayán

et al. 2019

Chemical Engineering Journal

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“…Low in cost and naturally abundant, α-Fe 2 O 3 is a promising oxygen carrier not only for CLC − but also for processes such as chemical looping reforming (CLR) and syngas chemical looping (SCL) gasification, all of which use two separate reactors. − One reactor is used to combust the hydrocarbon fuel by utilizing the lattice oxygen of the oxygen carrier, while the other reactor is used to regenerate the spent (i.e., reduced) oxygen carrier via oxidation in air. For these processes, α-Fe 2 O 3 is especially desirable because it possesses the highest theoretical oxygen capacity among transition metal oxides commonly considered for CLC at 30.1% (wt), assuming complete reduction to Fe via Fe 3 O 4 and FeO (e.g., see hematite stability diagram as a function of temperature and oxygen pressure in the paper by Ketteler and co-workers).…”

Section: Introductionmentioning

confidence: 99%

α-Fe₂O₃ Nanoparticles as Oxygen Carriers for Chemical Looping Combustion: An Integrated Materials Characterization Approach to Understanding Oxygen Carrier Performance, Reduction Mechanism, and Particle Size Effects

et al. 2018

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Through continuous flow reactor experiments, materials characterization, and theoretical calculations, we provide new insights into the reduction of hematite (α-Fe2O3) nanoparticles by methane (CH4) during chemical looping combustion (CLC). Across CLC-relevant temperatures (500–800 °C) and gas flow rates (2.5–250 h–1), decreasing α-Fe2O3 particle size (from 350 to 3 nm) increased the duration over which CH4 was completely converted to CO2 (i.e., 100% yield). We attribute this size-dependent performance trend to the greater availability of lattice oxygen atoms in the near-surface region of smaller particles with higher surface area-to-volume ratios. All particle sizes then exhibited a relatively rapid rate of reactivity loss that was size- and temperature-independent, reflecting a greater role for magnetite (Fe3O4), the primary α-Fe2O3 reduction product, in CH4 oxidation. Bulk (X-ray diffraction, XRD) and surface (X-ray photoelectron spectroscopy, XPS) analysis revealed that oxygen carrier reduction proceeds via a two-stage solid-state mechanism; α-Fe2O3 reduction to Fe3O4 followed the unreacted shrinking core model (USCM) while subsequent reduction of Fe3O4 to wüstite (FeO) and FeO to iron metal (Fe) followed the nucleation and nuclei growth model (NNGM). Atomistic thermodynamics modeling based on density functional theory supports that reduction initiates via the USCM, as partially reduced α-Fe2O3 surfaces exhibited a wide range of stability relative to bulk Fe3O4. Reduction and reoxidation cycling experiments were also performed to explore more practical aspects related to the long-term performance of unsupported α-Fe2O3 nanoparticles as oxygen carriers for CLC.

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“…From the Arrhenius plot, the apparent activation energy of the reduction under plasma conditions is estimated to be 12.79 kJ mol −1 . Hua et al 26 reported that the apparent activation energy of the reduction of Fe 2 O 3 /Al 2 O 3 by CO under thermal conditions was 41.1 ± 2.0 kJ mol −1 , which is 3 times higher than that under plasma. These results suggest that plasma activation offers a pathway with a lower energy barrier, thus allowing the reaction to proceed at medium temperatures.…”

Section: Resultsmentioning

confidence: 96%

Performance of plasma-assisted chemical looping hydrogen generation at moderate temperature

Wang

Liu

Qiu

et al. 2023

Sustainable Energy Fuels

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Performance and kinetics of iron-based oxygen carriers reduced by carbon monoxide for chemical looping combustion

Cited by 13 publications

References 26 publications

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

α-Fe₂O₃ Nanoparticles as Oxygen Carriers for Chemical Looping Combustion: An Integrated Materials Characterization Approach to Understanding Oxygen Carrier Performance, Reduction Mechanism, and Particle Size Effects

Performance of plasma-assisted chemical looping hydrogen generation at moderate temperature

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Performance and kinetics of iron-based oxygen carriers reduced by carbon monoxide for chemical looping combustion

Cited by 13 publications

References 26 publications

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

Reduction and oxidation kinetics of Tierga iron ore for Chemical Looping Combustion with diverse fuels

α-Fe2O3 Nanoparticles as Oxygen Carriers for Chemical Looping Combustion: An Integrated Materials Characterization Approach to Understanding Oxygen Carrier Performance, Reduction Mechanism, and Particle Size Effects

Performance of plasma-assisted chemical looping hydrogen generation at moderate temperature

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α-Fe₂O₃ Nanoparticles as Oxygen Carriers for Chemical Looping Combustion: An Integrated Materials Characterization Approach to Understanding Oxygen Carrier Performance, Reduction Mechanism, and Particle Size Effects