Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift
Nickel phosphide catalysts show a high level of selectivity for the reverse water-gas shift (RWGS) reaction, inhibiting the competing methanation reaction. This work investigates the extent to which suppression of methanation can be controlled by phosphidation and tests the stability of phosphide ph...
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| Format: | Article |
| Language: | English |
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Elsevier
2023-11-01
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| Series: | Journal of CO2 Utilization |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2212982023002172 |
| _version_ | 1827739797603483648 |
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| author | Gul Hameed Ali Goksu Loukia-Pantzechroula Merkouri Anna Penkova Tomas Ramirez Reina Sergio Carrasco Ruiz Melis Seher Duyar |
| author_facet | Gul Hameed Ali Goksu Loukia-Pantzechroula Merkouri Anna Penkova Tomas Ramirez Reina Sergio Carrasco Ruiz Melis Seher Duyar |
| author_sort | Gul Hameed |
| collection | DOAJ |
| description | Nickel phosphide catalysts show a high level of selectivity for the reverse water-gas shift (RWGS) reaction, inhibiting the competing methanation reaction. This work investigates the extent to which suppression of methanation can be controlled by phosphidation and tests the stability of phosphide phases over 24-hour time on stream. Herein the synthesis of different phosphide crystal structures by varying Ni/P atomic ratios (from 0.5 to 2.4) is shown to affect the selectivity to CO over CH4 in a significant way. We also show that the activity of these catalysts can be fine-tuned by the synthesis Ni/P ratio and identify suitable catalysts for low temperature RWGS process. Ni12P5-SiO2 showed 80–100% selectivity over the full temperature range (i.e., 300–800 °C) tested, reaching 73% CO2 conversion at 800 °C. Ni2P-SiO2 exhibited CO selectivity of 93–100% over a full temperature range, and 70% CO2 conversion at 800 °C. The highest CO2 conversions for Ni12P5-SiO2 at all temperatures among all catalysts showed its promising nature for CO2 capture and utilisation. The methanation reaction was suppressed in addition to RWGS activity improvement through the formation of nickel phosphide phases, and the crystal structure was found to determine CO selectivity, with the following order Ni12P5 >Ni2P > Ni3P. Based on the activity of the studied catalysts, the catalysts were ranked in order of suitability for the RWGS reaction as follows: Ni12P5-SiO2 (Ni/P = 2.4) > Ni2P-SiO2 (Ni/P = 2) > NiP-SiO2 (Ni/P = 1) > NiP2-SiO2 (Ni/P = 0.5). Two catalysts with Ni/P atomic ratios; 2.4 and 2, were selected for stability testing. The catalyst with Ni/P ratio = 2.4 (i.e., Ni12P5-SiO2) was found to be more stable in terms of CO2 conversion and CO yield over the 24-hour duration at 550 °C. Using the phosphidation strategy to tune both selectivity and activity of Ni catalysts for RWGS, methanation as a competing reaction is shown to be no longer a critical issue in the RWGS process for catalysts with high Ni/P atomic ratios (2.4 and 2) even at lower temperatures (300–500 °C). This opens up potential low temperature RWGS opportunities, especially coupled to downstream or tandem lower temperature processes to produce liquid fuels. |
| first_indexed | 2024-03-11T03:13:09Z |
| format | Article |
| id | doaj.art-1fd143fcd3614c6691d89b31e6323680 |
| institution | Directory Open Access Journal |
| issn | 2212-9839 |
| language | English |
| last_indexed | 2024-03-11T03:13:09Z |
| publishDate | 2023-11-01 |
| publisher | Elsevier |
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| series | Journal of CO2 Utilization |
| spelling | doaj.art-1fd143fcd3614c6691d89b31e63236802023-11-18T04:28:39ZengElsevierJournal of CO2 Utilization2212-98392023-11-0177102606Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shiftGul Hameed0Ali Goksu1Loukia-Pantzechroula Merkouri2Anna Penkova3Tomas Ramirez Reina4Sergio Carrasco Ruiz5Melis Seher Duyar6School of Chemistry and Chemical Engineering, University of Surrey, Guildford GU2 7XH, UKSchool of Chemistry and Chemical Engineering, University of Surrey, Guildford GU2 7XH, UKSchool of Chemistry and Chemical Engineering, University of Surrey, Guildford GU2 7XH, UKDepartment of Inorganic Chemistry and Materials Sciences Institute, University of Seville-CSIC, 41092 Seville, SpainSchool of Chemistry and Chemical Engineering, University of Surrey, Guildford GU2 7XH, UK; Department of Inorganic Chemistry and Materials Sciences Institute, University of Seville-CSIC, 41092 Seville, SpainDepartment of Inorganic Chemistry and Materials Sciences Institute, University of Seville-CSIC, 41092 Seville, SpainSchool of Chemistry and Chemical Engineering, University of Surrey, Guildford GU2 7XH, UK; Corresponding author.Nickel phosphide catalysts show a high level of selectivity for the reverse water-gas shift (RWGS) reaction, inhibiting the competing methanation reaction. This work investigates the extent to which suppression of methanation can be controlled by phosphidation and tests the stability of phosphide phases over 24-hour time on stream. Herein the synthesis of different phosphide crystal structures by varying Ni/P atomic ratios (from 0.5 to 2.4) is shown to affect the selectivity to CO over CH4 in a significant way. We also show that the activity of these catalysts can be fine-tuned by the synthesis Ni/P ratio and identify suitable catalysts for low temperature RWGS process. Ni12P5-SiO2 showed 80–100% selectivity over the full temperature range (i.e., 300–800 °C) tested, reaching 73% CO2 conversion at 800 °C. Ni2P-SiO2 exhibited CO selectivity of 93–100% over a full temperature range, and 70% CO2 conversion at 800 °C. The highest CO2 conversions for Ni12P5-SiO2 at all temperatures among all catalysts showed its promising nature for CO2 capture and utilisation. The methanation reaction was suppressed in addition to RWGS activity improvement through the formation of nickel phosphide phases, and the crystal structure was found to determine CO selectivity, with the following order Ni12P5 >Ni2P > Ni3P. Based on the activity of the studied catalysts, the catalysts were ranked in order of suitability for the RWGS reaction as follows: Ni12P5-SiO2 (Ni/P = 2.4) > Ni2P-SiO2 (Ni/P = 2) > NiP-SiO2 (Ni/P = 1) > NiP2-SiO2 (Ni/P = 0.5). Two catalysts with Ni/P atomic ratios; 2.4 and 2, were selected for stability testing. The catalyst with Ni/P ratio = 2.4 (i.e., Ni12P5-SiO2) was found to be more stable in terms of CO2 conversion and CO yield over the 24-hour duration at 550 °C. Using the phosphidation strategy to tune both selectivity and activity of Ni catalysts for RWGS, methanation as a competing reaction is shown to be no longer a critical issue in the RWGS process for catalysts with high Ni/P atomic ratios (2.4 and 2) even at lower temperatures (300–500 °C). This opens up potential low temperature RWGS opportunities, especially coupled to downstream or tandem lower temperature processes to produce liquid fuels.http://www.sciencedirect.com/science/article/pii/S2212982023002172Reverse water-gas shiftCO2 utilizationNickel phosphideHydrogenationThermochemical CO2 reduction |
| spellingShingle | Gul Hameed Ali Goksu Loukia-Pantzechroula Merkouri Anna Penkova Tomas Ramirez Reina Sergio Carrasco Ruiz Melis Seher Duyar Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift Journal of CO2 Utilization Reverse water-gas shift CO2 utilization Nickel phosphide Hydrogenation Thermochemical CO2 reduction |
| title | Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift |
| title_full | Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift |
| title_fullStr | Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift |
| title_full_unstemmed | Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift |
| title_short | Experimental optimization of Ni/P atomic ratio for nickel phosphide catalysts in reverse water-gas shift |
| title_sort | experimental optimization of ni p atomic ratio for nickel phosphide catalysts in reverse water gas shift |
| topic | Reverse water-gas shift CO2 utilization Nickel phosphide Hydrogenation Thermochemical CO2 reduction |
| url | http://www.sciencedirect.com/science/article/pii/S2212982023002172 |
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