Studies on reduction of chromium doped iron oxide catalyst using hydrogen and various concentration of carbon monoxide

Tengku Shafazila Tengku Saharuddin, Alinda Samsuri, Fairous Salleh, Rizafizah Othaman, Mohammad Kassim, Mohamed Wahab Mohamed Hisham, Mohd. Ambar Yarmo

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Chemical reduction behaviour of 3% chromium doped (Cr-Fe2O3) and undoped iron oxides (Fe2O3) were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The reduction processes were achieved with 10% H2 in nitrogen (%, v/v), 10% and 20% of carbon monoxide (CO) in nitrogen (%, v/v). In hydrogen atmosphere, the TPR results indicate that the reduction of Cr-Fe2O3 and Fe2O3 proceed in three steps (Fe2O3 → Fe3O4 → FeO → Fe) with Fe3O4 and FeO as intermediate states. A complete reduction to metallic iron for both samples occurred at 900 °C. As for CO reductant, the profiles show the reduction of Fe2O3 also proceeded in three steps with a complete reduction occurs at 900 °C in 10% CO with no sign of carbide formation. Nevertheless, a 20% CO was able to reduce the completely at lower temperature at 700 °C and there is a formation of iron carbide at 500 °C but the carbide disappeared as the reduction temperature increase. Meanwhile in 10% CO atmosphere, Cr-Fe2O3 shows a better reducibility compared to Fe2O3 with a complete reduction at 700 °C, which is 200 °C lower than Fe2O3. A Cr dopant in the Fe2O3 can lead to formation of various forms of iron carbides such as F2C, Fe5C2, Fe23C6 and Fe3C as the CO concentration was increased to 20%. The transformation profile of iron phases during carburization follows the following forms, Fe2O3 → Fe3O4 → iron carbides (FexC). The XRD pattern shows the diffraction peaks of Cr-Fe2O3 are more intense with improved crystallinity for the characteristic peaks of Fe2O3 compare to undoped Fe2O3. No visible sign of chromium particles peaks in the XRD spectrum that indicates the Cr particles loaded onto the iron oxide are well dispersed. The uniform dispersion with no sign of sintering effects of the Cr dopant on the Fe2O3 was confirmed by FESEM. The study shows that Cr dopant gives a better reducibility of iron oxide but promotes the formation of carbides in an excess CO concentration.

Original languageEnglish
JournalInternational Journal of Hydrogen Energy
DOIs
Publication statusAccepted/In press - 26 Oct 2015

Fingerprint

Iron oxides
iron oxides
Carbon monoxide
carbon monoxide
chromium
Chromium
catalysts
carbides
Hydrogen
Catalysts
Carbides
hydrogen
iron
Iron
Doping (additives)
diffraction
Spectroscopy
X ray diffraction
spectroscopy
nitrogen

Keywords

  • Carbide
  • Carbon monoxide
  • Chromium
  • Hydrogen
  • Iron oxide
  • TPR

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

Cite this

Studies on reduction of chromium doped iron oxide catalyst using hydrogen and various concentration of carbon monoxide. / Saharuddin, Tengku Shafazila Tengku; Samsuri, Alinda; Salleh, Fairous; Othaman, Rizafizah; Kassim, Mohammad; Mohamed Hisham, Mohamed Wahab; Yarmo, Mohd. Ambar.

In: International Journal of Hydrogen Energy, 26.10.2015.

Research output: Contribution to journalArticle

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abstract = "Chemical reduction behaviour of 3{\%} chromium doped (Cr-Fe2O3) and undoped iron oxides (Fe2O3) were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The reduction processes were achieved with 10{\%} H2 in nitrogen ({\%}, v/v), 10{\%} and 20{\%} of carbon monoxide (CO) in nitrogen ({\%}, v/v). In hydrogen atmosphere, the TPR results indicate that the reduction of Cr-Fe2O3 and Fe2O3 proceed in three steps (Fe2O3 → Fe3O4 → FeO → Fe) with Fe3O4 and FeO as intermediate states. A complete reduction to metallic iron for both samples occurred at 900 °C. As for CO reductant, the profiles show the reduction of Fe2O3 also proceeded in three steps with a complete reduction occurs at 900 °C in 10{\%} CO with no sign of carbide formation. Nevertheless, a 20{\%} CO was able to reduce the completely at lower temperature at 700 °C and there is a formation of iron carbide at 500 °C but the carbide disappeared as the reduction temperature increase. Meanwhile in 10{\%} CO atmosphere, Cr-Fe2O3 shows a better reducibility compared to Fe2O3 with a complete reduction at 700 °C, which is 200 °C lower than Fe2O3. A Cr dopant in the Fe2O3 can lead to formation of various forms of iron carbides such as F2C, Fe5C2, Fe23C6 and Fe3C as the CO concentration was increased to 20{\%}. The transformation profile of iron phases during carburization follows the following forms, Fe2O3 → Fe3O4 → iron carbides (FexC). The XRD pattern shows the diffraction peaks of Cr-Fe2O3 are more intense with improved crystallinity for the characteristic peaks of Fe2O3 compare to undoped Fe2O3. No visible sign of chromium particles peaks in the XRD spectrum that indicates the Cr particles loaded onto the iron oxide are well dispersed. The uniform dispersion with no sign of sintering effects of the Cr dopant on the Fe2O3 was confirmed by FESEM. The study shows that Cr dopant gives a better reducibility of iron oxide but promotes the formation of carbides in an excess CO concentration.",
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AU - Saharuddin, Tengku Shafazila Tengku

AU - Samsuri, Alinda

AU - Salleh, Fairous

AU - Othaman, Rizafizah

AU - Kassim, Mohammad

AU - Mohamed Hisham, Mohamed Wahab

AU - Yarmo, Mohd. Ambar

PY - 2015/10/26

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N2 - Chemical reduction behaviour of 3% chromium doped (Cr-Fe2O3) and undoped iron oxides (Fe2O3) were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The reduction processes were achieved with 10% H2 in nitrogen (%, v/v), 10% and 20% of carbon monoxide (CO) in nitrogen (%, v/v). In hydrogen atmosphere, the TPR results indicate that the reduction of Cr-Fe2O3 and Fe2O3 proceed in three steps (Fe2O3 → Fe3O4 → FeO → Fe) with Fe3O4 and FeO as intermediate states. A complete reduction to metallic iron for both samples occurred at 900 °C. As for CO reductant, the profiles show the reduction of Fe2O3 also proceeded in three steps with a complete reduction occurs at 900 °C in 10% CO with no sign of carbide formation. Nevertheless, a 20% CO was able to reduce the completely at lower temperature at 700 °C and there is a formation of iron carbide at 500 °C but the carbide disappeared as the reduction temperature increase. Meanwhile in 10% CO atmosphere, Cr-Fe2O3 shows a better reducibility compared to Fe2O3 with a complete reduction at 700 °C, which is 200 °C lower than Fe2O3. A Cr dopant in the Fe2O3 can lead to formation of various forms of iron carbides such as F2C, Fe5C2, Fe23C6 and Fe3C as the CO concentration was increased to 20%. The transformation profile of iron phases during carburization follows the following forms, Fe2O3 → Fe3O4 → iron carbides (FexC). The XRD pattern shows the diffraction peaks of Cr-Fe2O3 are more intense with improved crystallinity for the characteristic peaks of Fe2O3 compare to undoped Fe2O3. No visible sign of chromium particles peaks in the XRD spectrum that indicates the Cr particles loaded onto the iron oxide are well dispersed. The uniform dispersion with no sign of sintering effects of the Cr dopant on the Fe2O3 was confirmed by FESEM. The study shows that Cr dopant gives a better reducibility of iron oxide but promotes the formation of carbides in an excess CO concentration.

AB - Chemical reduction behaviour of 3% chromium doped (Cr-Fe2O3) and undoped iron oxides (Fe2O3) were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The reduction processes were achieved with 10% H2 in nitrogen (%, v/v), 10% and 20% of carbon monoxide (CO) in nitrogen (%, v/v). In hydrogen atmosphere, the TPR results indicate that the reduction of Cr-Fe2O3 and Fe2O3 proceed in three steps (Fe2O3 → Fe3O4 → FeO → Fe) with Fe3O4 and FeO as intermediate states. A complete reduction to metallic iron for both samples occurred at 900 °C. As for CO reductant, the profiles show the reduction of Fe2O3 also proceeded in three steps with a complete reduction occurs at 900 °C in 10% CO with no sign of carbide formation. Nevertheless, a 20% CO was able to reduce the completely at lower temperature at 700 °C and there is a formation of iron carbide at 500 °C but the carbide disappeared as the reduction temperature increase. Meanwhile in 10% CO atmosphere, Cr-Fe2O3 shows a better reducibility compared to Fe2O3 with a complete reduction at 700 °C, which is 200 °C lower than Fe2O3. A Cr dopant in the Fe2O3 can lead to formation of various forms of iron carbides such as F2C, Fe5C2, Fe23C6 and Fe3C as the CO concentration was increased to 20%. The transformation profile of iron phases during carburization follows the following forms, Fe2O3 → Fe3O4 → iron carbides (FexC). The XRD pattern shows the diffraction peaks of Cr-Fe2O3 are more intense with improved crystallinity for the characteristic peaks of Fe2O3 compare to undoped Fe2O3. No visible sign of chromium particles peaks in the XRD spectrum that indicates the Cr particles loaded onto the iron oxide are well dispersed. The uniform dispersion with no sign of sintering effects of the Cr dopant on the Fe2O3 was confirmed by FESEM. The study shows that Cr dopant gives a better reducibility of iron oxide but promotes the formation of carbides in an excess CO concentration.

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