Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction Temperature
The catalyst regeneration is still a challenge to make the ethanol steam reforming (ESR) process feasible for sustainable H<sub>2</sub> production. NiAl<sub>2</sub>O<sub>4</sub> spinel derived catalysts are highly active and selective for ESR, but they require avo...
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MDPI AG
2022-05-01
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| Series: | Catalysts |
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| Online Access: | https://www.mdpi.com/2073-4344/12/5/550 |
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| author | Sergio Iglesias-Vázquez José Valecillos Aingeru Remiro Javier Bilbao Ana Guadalupe Gayubo |
| author_facet | Sergio Iglesias-Vázquez José Valecillos Aingeru Remiro Javier Bilbao Ana Guadalupe Gayubo |
| author_sort | Sergio Iglesias-Vázquez |
| collection | DOAJ |
| description | The catalyst regeneration is still a challenge to make the ethanol steam reforming (ESR) process feasible for sustainable H<sub>2</sub> production. NiAl<sub>2</sub>O<sub>4</sub> spinel derived catalysts are highly active and selective for ESR, but they require avoiding irreversible deactivation to ensure their regeneration. Their stability depends on the catalyst structure, and herein we report different Ni/Al<sub>2</sub>O<sub>3</sub>-NiAl<sub>2</sub>O<sub>4</sub> catalysts obtained upon reduction of a NiAl<sub>2</sub>O<sub>4</sub> spinel at 700, 750, or 850 °C. The catalysts were tested in ESR reaction-regeneration cycles, with reaction at 600 °C and regeneration by coke combustion at 850 °C followed by reduction at the corresponding temperature. The fresh, spent, and regenerated catalysts were characterized using X-ray diffraction, N<sub>2</sub> physisorption, temperature programmed reduction and oxidation, and scanning electron microscopy. The irreversible deactivation is due to Ni volatilization and catalyst particle fragmentation. These phenomena are prompted by a high filamentous carbon deposition favored by the Al<sub>2</sub>O<sub>3</sub> content in the catalyst. The reduction in the 700–750 °C range is optimum for controlling the Al<sub>2</sub>O<sub>3</sub> content, increasing the NiAl<sub>2</sub>O<sub>4</sub>/Al<sub>2</sub>O<sub>3</sub> ratio in the resulting catalyst. These catalysts show a period of partial reversible deactivation by coke with a change in the H<sub>2</sub> formation mechanism reaching a pseudo-stable state with a H<sub>2</sub> yield of 40% and a reproducible performance in successive reaction-regeneration cycles. |
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| last_indexed | 2024-03-10T03:10:59Z |
| publishDate | 2022-05-01 |
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| series | Catalysts |
| spelling | doaj.art-cb366596fba74d77bb171659b5f611ac2023-11-23T10:26:31ZengMDPI AGCatalysts2073-43442022-05-0112555010.3390/catal12050550Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction TemperatureSergio Iglesias-Vázquez0José Valecillos1Aingeru Remiro2Javier Bilbao3Ana Guadalupe Gayubo4Department of Chemical Engineering, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, SpainDepartment of Chemical Engineering, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, SpainDepartment of Chemical Engineering, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, SpainDepartment of Chemical Engineering, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, SpainDepartment of Chemical Engineering, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, SpainThe catalyst regeneration is still a challenge to make the ethanol steam reforming (ESR) process feasible for sustainable H<sub>2</sub> production. NiAl<sub>2</sub>O<sub>4</sub> spinel derived catalysts are highly active and selective for ESR, but they require avoiding irreversible deactivation to ensure their regeneration. Their stability depends on the catalyst structure, and herein we report different Ni/Al<sub>2</sub>O<sub>3</sub>-NiAl<sub>2</sub>O<sub>4</sub> catalysts obtained upon reduction of a NiAl<sub>2</sub>O<sub>4</sub> spinel at 700, 750, or 850 °C. The catalysts were tested in ESR reaction-regeneration cycles, with reaction at 600 °C and regeneration by coke combustion at 850 °C followed by reduction at the corresponding temperature. The fresh, spent, and regenerated catalysts were characterized using X-ray diffraction, N<sub>2</sub> physisorption, temperature programmed reduction and oxidation, and scanning electron microscopy. The irreversible deactivation is due to Ni volatilization and catalyst particle fragmentation. These phenomena are prompted by a high filamentous carbon deposition favored by the Al<sub>2</sub>O<sub>3</sub> content in the catalyst. The reduction in the 700–750 °C range is optimum for controlling the Al<sub>2</sub>O<sub>3</sub> content, increasing the NiAl<sub>2</sub>O<sub>4</sub>/Al<sub>2</sub>O<sub>3</sub> ratio in the resulting catalyst. These catalysts show a period of partial reversible deactivation by coke with a change in the H<sub>2</sub> formation mechanism reaching a pseudo-stable state with a H<sub>2</sub> yield of 40% and a reproducible performance in successive reaction-regeneration cycles.https://www.mdpi.com/2073-4344/12/5/550hydrogenethanol steam reforming (ESR)Ni catalystNiAl<sub>2</sub>O<sub>4</sub> spinelcatalyst deactivationcoke |
| spellingShingle | Sergio Iglesias-Vázquez José Valecillos Aingeru Remiro Javier Bilbao Ana Guadalupe Gayubo Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction Temperature Catalysts hydrogen ethanol steam reforming (ESR) Ni catalyst NiAl<sub>2</sub>O<sub>4</sub> spinel catalyst deactivation coke |
| title | Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction Temperature |
| title_full | Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction Temperature |
| title_fullStr | Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction Temperature |
| title_full_unstemmed | Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction Temperature |
| title_short | Stability of a NiAl<sub>2</sub>O<sub>4</sub> Derived Catalyst in the Ethanol Steam Reforming in Reaction-Regeneration Cycles: Effect of Reduction Temperature |
| title_sort | stability of a nial sub 2 sub o sub 4 sub derived catalyst in the ethanol steam reforming in reaction regeneration cycles effect of reduction temperature |
| topic | hydrogen ethanol steam reforming (ESR) Ni catalyst NiAl<sub>2</sub>O<sub>4</sub> spinel catalyst deactivation coke |
| url | https://www.mdpi.com/2073-4344/12/5/550 |
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