The retardation kinetics of magnetite reduction using H2 and H2-H2O mixtures

Wan Ho Kim, Seungmoon Lee, Sung Man Kim, Dong Joon Min

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18 Citations (Scopus)

Abstract

Cylindrical compacts of magnetite were isothermally reduced at 773-1273 K with pure H2 or H2-H2O mixtures. The initial reduction rates increased with temperature and partial pressures of H 2 in the H2-H2O mixtures. However, with progressing reduction, a dense iron layer formed around the wüstite grains and the rate significantly reduced. In this regime, solid state oxygen diffusion through the dense iron layer was rate limiting. This retardation of reduction occurred at degrees of reduction of 51-89%, depending on the temperature and H2 partial pressure, which has a linear relationship with the dimensionless kinetic parameter, k1mixed/k 2mixed, (k1mixed, k2 mixed: contribution of gaseous mass transport (GMT) and interfacial chemical reaction (ICR) to the reduction rate, respectively) in the reaction-regime controlled by a combination of both mechanisms. However, under certain conditions (H2, H2-10%H2O, 773 K//H2-10, 20%H2O, 873 K//H2-20%H2O, 973 K) the retardation was absent because of the formation of a microporous iron layer product.

Original languageEnglish
Pages (from-to)4194-4200
Number of pages7
JournalInternational Journal of Hydrogen Energy
Volume38
Issue number10
DOIs
Publication statusPublished - 2013 Apr 1

All Science Journal Classification (ASJC) codes

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

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