Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio Calculations
This paper presents a computational study of the mechanistic models for the laydown of carbon species on nickel surface facets and the burn-off models for their gasification mechanism in methane steam reforming based on density functional theory. Insights into catalyst design strategies for achievin...
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| Format: | Article |
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MDPI AG
2022-12-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/13/1/40 |
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| author | Aniekan Magnus Ukpong |
| author_facet | Aniekan Magnus Ukpong |
| author_sort | Aniekan Magnus Ukpong |
| collection | DOAJ |
| description | This paper presents a computational study of the mechanistic models for the laydown of carbon species on nickel surface facets and the burn-off models for their gasification mechanism in methane steam reforming based on density functional theory. Insights into catalyst design strategies for achieving the simultaneous inhibition of the laydown of polymeric carbon and the promotion of its burn-off are obtained by investigating the influence of single atom dopants on nickel surfaces. The effects of single atom dopants on adsorption energies are determined at both low and high carbon coverages on nickel and used to introduce appropriate thermodynamic descriptors of the associated surface reactions. It is found that the critical size of the nucleating polymeric carbon adatom contains three atoms, i.e., C<sub>3</sub>. The results show that the burn-off reaction of a polymeric carbon species is thermodynamically limited and hard to promote when the deposited carbon cluster grows beyond a critical size, C<sub>4</sub>. The introduction of single atom dopants into nickel surfaces is found to modify the structural stability and adsorption energies of carbon adatom species, as well as the free energy profiles of surface reactions for the burn-off reactions when CH<sub>4</sub>, H<sub>2</sub>O, H<sub>2</sub>, and CO species react to form hydrogen. The results reveal that materials development strategies that modify the sub-surface of the catalyst with potassium, strontium, or barium will inhibit carbon nucleation and promote burn-off, while surface doping with niobium, tungsten, or molybdenum will promote the laydown of polymeric carbon. This study provides underpinning insights into the reaction mechanisms for the coking of a nickel catalyst and the gasification routes that are possible for the recovery of a nickel catalyst during the steam reforming of methane for large-scale production of hydrogen. |
| first_indexed | 2024-03-09T03:29:49Z |
| format | Article |
| id | doaj.art-aee3f65f521d4ffa9ad242d7e062a5e4 |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-09T03:29:49Z |
| publishDate | 2022-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-aee3f65f521d4ffa9ad242d7e062a5e42023-12-03T14:58:15ZengMDPI AGNanomaterials2079-49912022-12-011314010.3390/nano13010040Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio CalculationsAniekan Magnus Ukpong0Theoretical and Computational Condensed Matter and Materials Physics Group (TCCMMP), School of Chemistry and Physics, University of KwaZulu-Natal, Pietermaritzburg 3201, South AfricaThis paper presents a computational study of the mechanistic models for the laydown of carbon species on nickel surface facets and the burn-off models for their gasification mechanism in methane steam reforming based on density functional theory. Insights into catalyst design strategies for achieving the simultaneous inhibition of the laydown of polymeric carbon and the promotion of its burn-off are obtained by investigating the influence of single atom dopants on nickel surfaces. The effects of single atom dopants on adsorption energies are determined at both low and high carbon coverages on nickel and used to introduce appropriate thermodynamic descriptors of the associated surface reactions. It is found that the critical size of the nucleating polymeric carbon adatom contains three atoms, i.e., C<sub>3</sub>. The results show that the burn-off reaction of a polymeric carbon species is thermodynamically limited and hard to promote when the deposited carbon cluster grows beyond a critical size, C<sub>4</sub>. The introduction of single atom dopants into nickel surfaces is found to modify the structural stability and adsorption energies of carbon adatom species, as well as the free energy profiles of surface reactions for the burn-off reactions when CH<sub>4</sub>, H<sub>2</sub>O, H<sub>2</sub>, and CO species react to form hydrogen. The results reveal that materials development strategies that modify the sub-surface of the catalyst with potassium, strontium, or barium will inhibit carbon nucleation and promote burn-off, while surface doping with niobium, tungsten, or molybdenum will promote the laydown of polymeric carbon. This study provides underpinning insights into the reaction mechanisms for the coking of a nickel catalyst and the gasification routes that are possible for the recovery of a nickel catalyst during the steam reforming of methane for large-scale production of hydrogen.https://www.mdpi.com/2079-4991/13/1/40carbon laydownburn-offthermodynamic profiledensity functional theory |
| spellingShingle | Aniekan Magnus Ukpong Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio Calculations Nanomaterials carbon laydown burn-off thermodynamic profile density functional theory |
| title | Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio Calculations |
| title_full | Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio Calculations |
| title_fullStr | Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio Calculations |
| title_full_unstemmed | Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio Calculations |
| title_short | Inhibiting the Laydown of Polymeric Carbon and Simultaneously Promoting Its Facile Burn-Off during the Industrial-Scale Production of Hydrogen with Nickel-Based Catalysts: Insights from Ab Initio Calculations |
| title_sort | inhibiting the laydown of polymeric carbon and simultaneously promoting its facile burn off during the industrial scale production of hydrogen with nickel based catalysts insights from ab initio calculations |
| topic | carbon laydown burn-off thermodynamic profile density functional theory |
| url | https://www.mdpi.com/2079-4991/13/1/40 |
| work_keys_str_mv | AT aniekanmagnusukpong inhibitingthelaydownofpolymericcarbonandsimultaneouslypromotingitsfacileburnoffduringtheindustrialscaleproductionofhydrogenwithnickelbasedcatalystsinsightsfromabinitiocalculations |