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Title
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Ilmenite-CO reduction kinetics
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Author
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Abstract
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| Secondary ilmenite is an inexpensive mineral that is a potential oxygen carrier for the chemical looping process. It has excellent mechanical stability, adequate heat capacity to transfer heat from the air reactor to the fuel reactor, and possesses a modest oxygen transfer capacity. Fresh and preoxidized ilmenite can transfer up to 1.7% and 1.2% oxygen on a mass basis, when reduced for 2 min with CO at 910 °C. Preoxidizing ilmenite reduces its tendency to agglomerate but it also reduced its reactivity towards CO. We characterized the kinetics of the reduction of preoxidized secondary ilmenite from South Africa with a mechanistic model. The model assumes CO reacts with surface oxygen atoms, and that bulk oxygen replenishes the surface oxygen. The model accounts for more than 90% of the variance in the data. The activation energies of the surface reduction and reoxidation steps are 51 kJ mol−1 and 89 kJ mol−1, respectively. The surface site density decreases with the reduction cycles via the simple power law expression because sintering deactivates the catalyst. |
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Language
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English
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Source (journal)
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Fuel. - Guilford
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Publication
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Guilford
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2016
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ISSN
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0016-2361
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DOI
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10.1016/J.FUEL.2015.10.066
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Volume/pages
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165
(2016)
, p. 166-172
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ISI
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000364655000020
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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