CaFe2O4 oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application

Miller, Duane D.; Siriwardane, Ranjani

doi:10.1016/j.apenergy.2018.05.035

Title: CaFe₂O₄ oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application

Abstract

The calcium ferrite (CaFe₂O₄) oxygen carrier characterization during chemical looping coal gasification was conducted using X-ray diffraction and Raman spectroscopic analysis. Density functional theory (DFT) analysis and experimental data were used to elucidate the mechanism for the selective oxidation of coal char. The Raman spectroscopic analyses indicated that the initial reduction of CaFe₂O₄ were at the Fe₍₈₎O₆ and Fe₍₇₎O₆ octahedral sites which are related to the morphological changes at the [4 0 0] and [2 1 2] crystal planes. After the initial reduction, the Raman spectroscopic data indicated the remaining oxygen from Fe-O sites containing Ca (e.g. Fe–O–Ca) participated in the reduction reaction. Deep reduction of the CaFe₂O₄ led to the removal of oxygen from the Fe–O–Ca bonds, indicated by the decrease in Raman intensities of the corresponding species, and the appearance of the CaO and Fe⁰. The oxygen ion diffusion controlling regime was due to the oxygen transfer occurring at the Fe octahedral sites. Furthermore, these results indicated calcium functions to control both the movement of oxygen ions through the solid and the rate of carbon oxidation in coal char leading to the selective oxidation to produce CO, the desirable product of the chemical looping gasification application.

Authors:

Miller, Duane D. ^[1]; Siriwardane, Ranjani ^[2]

National Energy Technology Lab. (NETL), Morgantown, WV (United States); USA AECOM, Morgantown, WV (United States)
National Energy Technology Lab. (NETL), Morgantown, WV (United States)

Publication Date:: Thu May 17 00:00:00 EDT 2018

Research Org.:: National Energy Technology Lab. (NETL), Morgantown, WV (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1487392

Grant/Contract Number:: FE0004000

Resource Type:: Accepted Manuscript

Journal Name:: Applied Energy

Additional Journal Information:: Journal Volume: 224; Journal Issue: C; Journal ID: ISSN 0306-2619

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Gasification; CaFe2O4; Chemical looping; Raman spectroscopy; Coal

Citation Formats


                    Miller, Duane D., and Siriwardane, Ranjani. CaFe2O4 oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application.  United States: N. p., 2018. 
Web.  doi:10.1016/j.apenergy.2018.05.035.

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                    Miller, Duane D., & Siriwardane, Ranjani. CaFe2O4 oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application.  United States.  https://doi.org/10.1016/j.apenergy.2018.05.035

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                    Miller, Duane D., and Siriwardane, Ranjani. Thu .  
"CaFe2O4 oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application".  United States.  https://doi.org/10.1016/j.apenergy.2018.05.035.  https://www.osti.gov/servlets/purl/1487392.

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@article{osti_1487392,

  title        = {CaFe2O4 oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application},

  author       = {Miller, Duane D. and Siriwardane, Ranjani},

  abstractNote = {The calcium ferrite (CaFe2O4) oxygen carrier characterization during chemical looping coal gasification was conducted using X-ray diffraction and Raman spectroscopic analysis. Density functional theory (DFT) analysis and experimental data were used to elucidate the mechanism for the selective oxidation of coal char. The Raman spectroscopic analyses indicated that the initial reduction of CaFe2O4 were at the Fe(8)O6 and Fe(7)O6 octahedral sites which are related to the morphological changes at the [4 0 0] and [2 1 2] crystal planes. After the initial reduction, the Raman spectroscopic data indicated the remaining oxygen from Fe-O sites containing Ca (e.g. Fe–O–Ca) participated in the reduction reaction. Deep reduction of the CaFe2O4 led to the removal of oxygen from the Fe–O–Ca bonds, indicated by the decrease in Raman intensities of the corresponding species, and the appearance of the CaO and Fe0. The oxygen ion diffusion controlling regime was due to the oxygen transfer occurring at the Fe octahedral sites. Furthermore, these results indicated calcium functions to control both the movement of oxygen ions through the solid and the rate of carbon oxidation in coal char leading to the selective oxidation to produce CO, the desirable product of the chemical looping gasification application.},

  doi          = {10.1016/j.apenergy.2018.05.035},

  journal      = {Applied Energy},

  number       = C,

  volume       = 224,

  place        = {United States},

  year         = {Thu May 17 00:00:00 EDT 2018},

  month        = {Thu May 17 00:00:00 EDT 2018}

}

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Fig. 1: Elementary cell of CaFe₂O₄

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Title: CaFe2O4 oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application

Abstract

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Title: CaFe₂O₄ oxygen carrier characterization during the partial oxidation of coal in the chemical looping gasification application