An Experimental Study of Room Temperature Reoxidation Behavior of Direct H2-Reduced Iron in Air

Chiemeka Onyeka Okoye; Zhezi Zhang; Jianting Lin; Yuejun Liu; Xianchun Li; Shaoyan Wang; Darren Matthews; Tim J. Evans; Sunny Song; Dongke Zhang

doi:10.1021/acs.iecr.4c02196

An Experimental Study of Room Temperature Reoxidation Behavior of Direct H₂-Reduced Iron in Air

Chiemeka Onyeka Okoye, Zhezi Zhang, Jianting Lin, Yuejun Liu, Xianchun Li, Shaoyan Wang, Darren Matthews, Tim J. Evans, Sunny Song, Dongke Zhang

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

Abstract

Direct reduction of iron ore in hydrogen (25% H₂/N₂) between 450-1050 °C and subsequent room temperature reoxidation of the reduced iron in air was systematically examined using a TGA. The reduced samples with various degrees of metalization were cooled to room temperature in N₂ and then exposed to air. Weight gain due to iron reoxidation was observed. Cyclic reduction and reoxidation runs were also performed at selected reduction temperatures (T_r). Iron samples obtained at low reduction temperatures (450-850 °C) incurred pyrophoricity, with weight gain increasing with decreasing T_r. The weight gain behavior varied with reduction times (t_r) at different T_r. XRD characterization showed wustite, fayalite, and hercynite as intermediate mineral phases during reduction. BET results indicated that increasing T_r and t_r decreased the surface area and weight gain during reoxidation. The surface area and porous structure predominantly determine the pyrophoricity of the H₂-reduced iron.

Original language	English
Pages (from-to)	16102-16110
Number of pages	9
Journal	Industrial and Engineering Chemistry Research
Volume	63
Issue number	37
Early online date	3 Sept 2024
DOIs	https://doi.org/10.1021/acs.iecr.4c02196
Publication status	Published - 18 Sept 2024

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10.1021/acs.iecr.4c02196

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title = "An Experimental Study of Room Temperature Reoxidation Behavior of Direct H2-Reduced Iron in Air",

abstract = "Direct reduction of iron ore in hydrogen (25% H2/N2) between 450-1050 °C and subsequent room temperature reoxidation of the reduced iron in air was systematically examined using a TGA. The reduced samples with various degrees of metalization were cooled to room temperature in N2 and then exposed to air. Weight gain due to iron reoxidation was observed. Cyclic reduction and reoxidation runs were also performed at selected reduction temperatures (Tr). Iron samples obtained at low reduction temperatures (450-850 °C) incurred pyrophoricity, with weight gain increasing with decreasing Tr. The weight gain behavior varied with reduction times (tr) at different Tr. XRD characterization showed wustite, fayalite, and hercynite as intermediate mineral phases during reduction. BET results indicated that increasing Tr and tr decreased the surface area and weight gain during reoxidation. The surface area and porous structure predominantly determine the pyrophoricity of the H2-reduced iron.",

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doi = "10.1021/acs.iecr.4c02196",

language = "English",

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AU - Okoye, Chiemeka Onyeka

AU - Zhang, Zhezi

AU - Lin, Jianting

AU - Liu, Yuejun

AU - Li, Xianchun

AU - Wang, Shaoyan

AU - Matthews, Darren

AU - Evans, Tim J.

AU - Song, Sunny

AU - Zhang, Dongke

PY - 2024/9/18

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N2 - Direct reduction of iron ore in hydrogen (25% H2/N2) between 450-1050 °C and subsequent room temperature reoxidation of the reduced iron in air was systematically examined using a TGA. The reduced samples with various degrees of metalization were cooled to room temperature in N2 and then exposed to air. Weight gain due to iron reoxidation was observed. Cyclic reduction and reoxidation runs were also performed at selected reduction temperatures (Tr). Iron samples obtained at low reduction temperatures (450-850 °C) incurred pyrophoricity, with weight gain increasing with decreasing Tr. The weight gain behavior varied with reduction times (tr) at different Tr. XRD characterization showed wustite, fayalite, and hercynite as intermediate mineral phases during reduction. BET results indicated that increasing Tr and tr decreased the surface area and weight gain during reoxidation. The surface area and porous structure predominantly determine the pyrophoricity of the H2-reduced iron.

AB - Direct reduction of iron ore in hydrogen (25% H2/N2) between 450-1050 °C and subsequent room temperature reoxidation of the reduced iron in air was systematically examined using a TGA. The reduced samples with various degrees of metalization were cooled to room temperature in N2 and then exposed to air. Weight gain due to iron reoxidation was observed. Cyclic reduction and reoxidation runs were also performed at selected reduction temperatures (Tr). Iron samples obtained at low reduction temperatures (450-850 °C) incurred pyrophoricity, with weight gain increasing with decreasing Tr. The weight gain behavior varied with reduction times (tr) at different Tr. XRD characterization showed wustite, fayalite, and hercynite as intermediate mineral phases during reduction. BET results indicated that increasing Tr and tr decreased the surface area and weight gain during reoxidation. The surface area and porous structure predominantly determine the pyrophoricity of the H2-reduced iron.

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JO - Industrial and Engineering Chemistry Research

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ER -

An Experimental Study of Room Temperature Reoxidation Behavior of Direct H₂-Reduced Iron in Air

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Carbon-Supported Iron Catalysts for Selective Catalytic Reduction of NO

Mechanisms of Ammonia (NH3) Combustion and Nitrogen Oxides (NOx) Formation

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An Experimental Study of Room Temperature Reoxidation Behavior of Direct H2-Reduced Iron in Air

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Carbon-Supported Iron Catalysts for Selective Catalytic Reduction of NO

Mechanisms of Ammonia (NH3) Combustion and Nitrogen Oxides (NOx) Formation

Cite this

An Experimental Study of Room Temperature Reoxidation Behavior of Direct H₂-Reduced Iron in Air