Unraveling the thermodynamics and mechanism behind the lowering of reduction temperatures in oxide mixtures
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arXiv
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| Auteurs principaux: | , , , , , , , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866913798114246656 |
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| author | Shankar, Shiv Ratzker, Barak da Silva, Alisson Kwiatkowski Schwarz, Tim M. Brouwer, Hans Gault, Baptiste Ma, Yan Raabe, Dierk |
| author_facet | Shankar, Shiv Ratzker, Barak da Silva, Alisson Kwiatkowski Schwarz, Tim M. Brouwer, Hans Gault, Baptiste Ma, Yan Raabe, Dierk |
| contents | Hydrogen-based direct reduction offers a sustainable pathway to decarbonize the metal production industry. However, stable metal oxides, like Cr$_2$O$_3$, are notoriously difficult to reduce, requiring extremely high temperatures (above 1300 $^\circ$C). Herein, we show how reducing mixed oxides can be leveraged to lower hydrogen-based reduction temperatures of stable oxides and produce alloys in a single process. Using a newly developed thermodynamic framework, we predict the precise conditions (oxygen partial pressure, temperature, and oxide composition) needed for co-reduction. We showcase this approach by reducing Cr$_2$O$_3$ mixed with Fe$_2$O$_3$ at 1100 $^\circ$C, significantly lowering reduction temperatures (by $\geq$200 $^\circ$C). Our model and post-reduction atom probe tomography analysis elucidate that the temperature-lowering effect is driven by the lower chemical activity of Cr in the metallic phase. This strategy achieves low-temperature co-reduction of mixed oxides, dramatically reducing energy consumption and CO$_2$ emissions, while unlocking transformative pathways toward sustainable alloy design. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_12947 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unraveling the thermodynamics and mechanism behind the lowering of reduction temperatures in oxide mixtures Shankar, Shiv Ratzker, Barak da Silva, Alisson Kwiatkowski Schwarz, Tim M. Brouwer, Hans Gault, Baptiste Ma, Yan Raabe, Dierk Materials Science Hydrogen-based direct reduction offers a sustainable pathway to decarbonize the metal production industry. However, stable metal oxides, like Cr$_2$O$_3$, are notoriously difficult to reduce, requiring extremely high temperatures (above 1300 $^\circ$C). Herein, we show how reducing mixed oxides can be leveraged to lower hydrogen-based reduction temperatures of stable oxides and produce alloys in a single process. Using a newly developed thermodynamic framework, we predict the precise conditions (oxygen partial pressure, temperature, and oxide composition) needed for co-reduction. We showcase this approach by reducing Cr$_2$O$_3$ mixed with Fe$_2$O$_3$ at 1100 $^\circ$C, significantly lowering reduction temperatures (by $\geq$200 $^\circ$C). Our model and post-reduction atom probe tomography analysis elucidate that the temperature-lowering effect is driven by the lower chemical activity of Cr in the metallic phase. This strategy achieves low-temperature co-reduction of mixed oxides, dramatically reducing energy consumption and CO$_2$ emissions, while unlocking transformative pathways toward sustainable alloy design. |
| title | Unraveling the thermodynamics and mechanism behind the lowering of reduction temperatures in oxide mixtures |
| topic | Materials Science |
| url | https://arxiv.org/abs/2504.12947 |