Role of phosphorous in transition metal phosphides for selective hydrogenolysis of hindered C–O bonds

Waldt, Conor T.; Montalvo-Castro, Hansel; Almithn, Abdulrahman; Loaiza-Orduz, Álvaro; Plaisance, Craig; Hibbitts, David

doi:10.1016/j.jcat.2023.02.011

Cited by 6 publications

(5 citation statements)

References 88 publications

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“…The Fe-Fe bond distance in Fe 2 P(001) is larger (3.06 Å) compared to the Fe-Fe bond distances in the Fe(110) catalyst (2.48 Å). We have also shown previously that the incorporation of the phosphorus atom in Fe 2 P(001) results in a cationic shift in the surface Fe atoms to +0.09 e [27]. These modifications in the electronic structure and surface geometry induced by phosphorus likely contribute to the observed differences in the N-N activation pathways on Fe 2 P(001).…”

Section: N-n Bond Activation Pathways On Fe 2 P(001)supporting

confidence: 70%

“…Interestingly, this weakening does not extend to N 2 or NH 3 , which show slightly increased binding energies on Fe 2 P. These observations can be understood by considering the electronic effects of phosphorus. Previous DFT studies on Ni 2 P catalysts for selective C-O bond cleavage suggest that the addition of phosphorus introduces Lewis acid sites [27,31]. This Lewis acidity arises from a small charge transfer from the transition metal (Fe in our case) to phosphorus.…”

Section: Optimized Adsorbates and Their Binding Energiesmentioning

confidence: 58%

“…Furthermore, phosphorus incorporation improved activity and selectivity in other reactions, such as methanol steam reforming and methane activation [25,26]. These findings suggest that phosphorus modification could potentially fine-tune catalytic properties for specific target reactions [27].…”

Section: Introductionmentioning

confidence: 86%

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Phosphorus Modification of Iron: Mechanistic Insights into Ammonia Synthesis on Fe2P Catalyst

Almithn

2024

Molecules

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Ammonia (NH3) is a critical chemical for fertilizer production and a potential future energy carrier within a sustainable hydrogen economy. The industrial Haber–Bosch process, though effective, operates under harsh conditions due to the high thermodynamic stability of the nitrogen molecule (N2). This motivates the search for alternative catalysts that facilitate ammonia synthesis at milder temperatures and pressures. Theoretical and experimental studies suggest that circumventing the trade-off between N–N activation and subsequent NHx hydrogenation, governed by the Brønsted–Evans–Polanyi (BEP) relationship, is key to achieving this goal. Recent studies indicate metal phosphides as promising catalyst materials. In this work, a comprehensive density functional theory (DFT) study comparing the mechanisms and potential reaction pathways for ammonia synthesis on Fe(110) and Fe2P(001) is presented. The results reveal substantial differences in the adsorption strengths of NHx intermediates, with Fe2P(001) exhibiting weaker binding compared to Fe(110). For N–N bond cleavage, multiple competing pathways become viable on Fe2P(001), including routes involving the pre-hydrogenation of adsorbed N2 (e.g., through *NNH*). Analysis of DFT-derived turnover rates as a function of hydrogen pressure (H2) highlights the increased importance of these hydrogenated intermediates on Fe2P(001) compared to Fe(110) where direct N2 dissociation dominates. These findings suggest that phosphorus incorporation modifies the ammonia synthesis mechanism, offering alternative pathways that may circumvent the limitations of traditional transition metal catalysts. This work provides theoretical insights for the rational design of Fe-based catalysts and motivates further exploration of phosphide-based materials for sustainable ammonia production.

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Section: N-n Bond Activation Pathways On Fe 2 P(001)supporting

confidence: 70%

Section: Optimized Adsorbates and Their Binding Energiesmentioning

confidence: 58%

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Phosphorus Modification of Iron: Mechanistic Insights into Ammonia Synthesis on Fe2P Catalyst

Almithn

2024

Molecules

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“…The Ni 2 P(001) and Ni 3 P(001) surfaces both have an alternation of terminate planes with different Ni and P compositions in the z direction (Figure S14). − Some work indicated that P-rich termination surfaces such as Ni 2 P(001)-Ni3P2 and Ni 3 P(001)-Ni4P4 were found to be more stable, ,, while several other work indicated that Ni-rich terminations have the lowest surface formation energies. , It should be noted that the alternant terminations have comparable thermodynamic stability, and therefore, both surfaces can be formed over the nanoparticles of Ni 3 P and Ni 2 P. We calculated the charge of Ni atoms on these surfaces (Figure a and Table S5). The Ni atoms in the Ni(111) surface exhibited a similar charge with a value of −0.03 |e|, which showed the metallic state of Ni 0 .…”

Section: Resultsmentioning

confidence: 99%

Structural Ni⁰–Ni^δ+ Pair Sites for Highly Active Hydrogenation of Nitriles to Primary Amines

Lyu,

Jian,

Nie

et al. 2024

J. Am. Chem. Soc.

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Supported metal pair sites have sparked interest due to their tremendous potential as bifunctional catalysts. Here, we report the structural Ni 0 −Ni δ+ pair sites constructed in a welldefined nanocrystal phase of Ni 3 P. These Ni 0 −Ni δ+ pair sites exhibited a remarkable product formation rate of 123 mol BA / mol metal /h for the hydrogenation of benzonitrile (BN) to benzylamine (BA). The heterogeneity of surface Ni atoms over the Ni 3 P crystal created two types of metal centers, Ni 0 and Ni δ+ , with a specific spatial distance of 4−5 Å. The Ni 0 site acted as the center for H 2 activation, while the Ni δ+ site served as the adsorption and activation center for the C ≡ N group. The highly efficient cooperation effect of Ni 0 −Ni δ+ pair sites resulted in a TOF of 2915 h −1 in BN hydrogenation, which is 2.4 and 9.7 times higher than that over the mono-Ni 0 and -Ni δ+ sites, respectively.

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“…Increasing the P:Ni atomic ratio (i.e., Ni → Ni 12 P 5 → Ni 2 P) increases the selectivity towards 3 C–O bond cleavage. The geometric or electronic effects caused by the incorporation of P atoms with Ni appear to play a role in this unique selectivity to activate hindered C–O bonds [ 36 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of P:Ni Ratio on Methanol Steam Reforming on Nickel Phosphide Catalysts

Almithn

2023

Molecules

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This study investigates the influence of the phosphorus-to-nickel (P:Ni) ratio on methanol steam reforming (MSR) over nickel phosphide catalysts using density functional theory (DFT) calculations. The catalytic behavior of Ni(111) and Ni12P5(001) surfaces was explored and contrasted to our previous results from research on Ni2P(001). The DFT-predicted barriers reveal that Ni(111) predominantly favors the methanol decomposition route, where methanol is converted into carbon monoxide through a stepwise pathway involving CH3OH* → CH3O* → CH2O* → CHO* → CO*. On the other hand, Ni12P5 with a P:Ni atomic ratio of 0.42 (5:12) exhibits a substantial increase in selectivity towards methanol steam reforming (MSR) relative to methanol decomposition. In this pathway, formaldehyde is transformed into CO2 through a sequence of reactions involving CH2O*→ H2COOH* → HCOOH* → HCOO* → CO2. The introduction of phosphorus into the catalyst alters the surface morphology and electronic structure, favoring the MSR pathway. However, with a further increase in the P:Ni atomic ratio to 0.5 (1:2) on Ni2P catalysts, the selectivity towards MSR decreases, resulting in a more balanced competition between methanol decomposition and MSR. These results highlight the significance of tuning the P:Ni atomic ratio in designing efficient catalysts for the selective production of CO2 through the MSR route, offering valuable insights into optimizing nickel phosphide catalysts for desired chemical transformations.

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Role of phosphorous in transition metal phosphides for selective hydrogenolysis of hindered C–O bonds

Cited by 6 publications

References 88 publications

Phosphorus Modification of Iron: Mechanistic Insights into Ammonia Synthesis on Fe2P Catalyst

Phosphorus Modification of Iron: Mechanistic Insights into Ammonia Synthesis on Fe2P Catalyst

Structural Ni⁰–Ni^δ+ Pair Sites for Highly Active Hydrogenation of Nitriles to Primary Amines

Effects of P:Ni Ratio on Methanol Steam Reforming on Nickel Phosphide Catalysts

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Role of phosphorous in transition metal phosphides for selective hydrogenolysis of hindered C–O bonds

Cited by 6 publications

References 88 publications

Phosphorus Modification of Iron: Mechanistic Insights into Ammonia Synthesis on Fe2P Catalyst

Phosphorus Modification of Iron: Mechanistic Insights into Ammonia Synthesis on Fe2P Catalyst

Structural Ni0–Niδ+ Pair Sites for Highly Active Hydrogenation of Nitriles to Primary Amines

Effects of P:Ni Ratio on Methanol Steam Reforming on Nickel Phosphide Catalysts

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Structural Ni⁰–Ni^δ+ Pair Sites for Highly Active Hydrogenation of Nitriles to Primary Amines