Role of Lewis acid/base anchor atoms in catalyst regeneration: a comprehensive study on biomimetic EP3Fe nitrogenases

In the quest for sustainable ammonia synthesis routes, biomimetic complexes have been intensively studied. Here we focus on the Peter's group Fe-nitrogenase catalyst with EPPP scorpionate ligands, and explore the effect of anchor atom selection (B, Al, Ga, N and P) and the impact of chloro subs...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2024-04, Vol.26 (16), p.12520-12529
Main Authors: Kfoury, Joseph, Oláh, Julianna
Format: Article
Language:English
Subjects:
Affinity
Ammonia
Biomimetics
Catalysts
Hydrogen evolution reactions
Lewis acid
Nitrogenation
Protonation
Regeneration
Substitution reactions
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Summary:In the quest for sustainable ammonia synthesis routes, biomimetic complexes have been intensively studied. Here we focus on the Peter's group Fe-nitrogenase catalyst with EPPP scorpionate ligands, and explore the effect of anchor atom selection (B, Al, Ga, N and P) and the impact of chloro substitution on the phenyl rings on nitrogen fixation. The reaction profiles of complexes with Lewis basic anchor atoms exhibited energy-demanding reduction steps, with more exergonic protonation steps compared to the smoother reaction profiles observed for catalysts with Lewis acid anchor atoms, also implying that catalyst regeneration is especially challenging for catalysts with Lewis basic anchor atoms. The binding affinities of N2 and H2 to the complexes suggest that the autocatalytic hydrogen evolution reaction (HER), which ultimately leads to consumption of reactants and catalyst deactivation, is likely to become more prevalent for heavier anchor atoms and be more significant for Lewis basic anchor atom complexes. Out of the studied complexes, boron showed the smoothest reaction profile and the smallest affinity for H2, which supports its superiour role as an anchor atom in accordance with experimental data.
ISSN:1463-9076
1463-9084
DOI:10.1039/d4cp00483c