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. 2024 Aug 28;128(36):14978-14988.
doi: 10.1021/acs.jpcc.4c03959. eCollection 2024 Sep 12.

Selective Oxidation of Methanol to Methyl Formate on Gold: The Role of Low-Coordinated Sites Revealed by Isothermal Pulsed Molecular Beam Experiments and AIMD Simulations

Salma Eltayeb  1 , Lenard L Carroll  2   3 , Lukas Dippel  1 , Mersad Mostaghimi  2   4 , Wiebke Riedel  1 , Lyudmila V Moskaleva  2 , Thomas Risse  1
Affiliations

Selective Oxidation of Methanol to Methyl Formate on Gold: The Role of Low-Coordinated Sites Revealed by Isothermal Pulsed Molecular Beam Experiments and AIMD Simulations

Salma Eltayeb et al. J Phys Chem C Nanomater Interfaces. .

Abstract

To elucidate the role of low-coordinated sites in the partial methanol oxidation to methyl formate (MeFo), the isothermal reactivity of flat Au(111) and stepped Au(332) in pulsed molecular beam experiments was compared for a broad range of reaction conditions. Low-coordinated step sites were found to enhance MeFo selectivity, especially at low coverage conditions, as found at higher temperatures. The analysis of the transient kinetics provides evidence for the essential role of Au x O y phases for MeFo formation and the complex interplay of different oxygen species for the observed selectivity. Ab initio molecular dynamic simulations yielded microscopic insights in the formation of Au x O y phases on flat and stepped gold surfaces emphasizing the role of low-coordinated sites in their formation. Moreover, associated surface restructuring provides atomic-scale insights which align with the experimentally observed transient kinetics in MeFo formation.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
MeFo selectivity at the end of the O-pulse in isothermal, pulsed MB experiments on flat Au(111) (open triangles) and stepped Au(332) (filled circles) as a function of the surface temperature. In these measurements, a methanol flux of 52.7 × 1013 s–1 cm–2 and an O-flux of 0.08 × 1013 s–1 cm–2 were applied.
Figure 2
Figure 2
MeFo selectivity at the end of the O-pulse in isothermal, pulsed MB experiments on (a) stepped Au(332) and (b) flat Au(111) as a function of the surface temperature for different methanol and O-fluxes: A (black): methanol flux of 52.7 × 1013 s–1 cm–2 and an O-flux of 0.08 × 1013 s–1 cm–2, B (blue): methanol flux of 52.7 × 1013 s–1 cm–2 and an O-flux of 0.4 × 1013 s–1 cm–2, C (green): methanol flux of 4.3 × 1013 s–1 cm–2 and an O-flux of 0.4 × 1013 s–1 cm–2.
Figure 3
Figure 3
Transient MeFo formation kinetics for Au(111) at a low temperature of 190 K for different O-fluxes: (a) 0.04 × 1013 s–1 cm–2, (b) 0.08 × 1013 s–1 cm–2, (c) 0.17 × 1013 s–1 cm–2, (d) 0.4 × 1013 s–1 cm–2. The methanol flux in all experiments was 52.7 × 1013 s–1 cm–2. The gray shading indicates the duration of the O-pulse.
Figure 4
Figure 4
Transient MeFo formation kinetics for Au(332) at a rather low O-flux of 0.08 × 1013 s–1 cm–2 as a function of surface temperature. A methanol flux of 52.7 × 1013 s–1 cm–2 was applied in these experiments. The traces are normalized to the MeFo rate at the end of the O-pulse to allow for a direct comparison of the transient kinetic behavior. The gray shading indicates the duration of the O-pulse.
Figure 5
Figure 5
Snapshots from AIMD simulations illustrating different degree of surface restructuring induced by adsorbed atomic oxygen (top) and root-mean-square displacements (RMSD) of the different types of surface atoms (bottom) on (a) flat Au(111) with Au adatoms (oxygen coverage: 0.19 ML) and (b) stepped Au(221) (oxygen coverage: 0.17 ML). Dashed white lines in the initial snapshot (0 ps) indicate the position of the step edges. Color coding: Au, yellow; O, red; Au adatoms [Au(111) surface], orange.
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References

    1. Kaiser D.; Beckmann L.; Walter J.; Bertau M. Conversion of Green Methanol to Methyl Formate. Catalysts 2021, 11 (7), 869.10.3390/catal11070869. - DOI
    1. Lee J. S.; Kim J. C.; Kim Y. G. Methyl formate as a new building block in C1 chemistry. Appl. Catal. 1990, 57 (1), 1–30. 10.1016/S0166-9834(00)80720-4. - DOI
    1. Klezl P.Treibstoff für Verbrennungsmotoren und Verwendung von Methylformiat. EP 0501097 B1, 1995.
    1. Rong L.; Xu Z.; Sun J.; Guo G. New methyl formate synthesis method: Coal to methyl formate. J. Energy Chem. 2018, 27 (1), 238–242. 10.1016/j.jechem.2017.07.015. - DOI
    1. Sang R.; Wei Z. H.; Hu Y. Y.; Alberico E.; Wei D.; Tian X. X.; Ryabchuk P.; Spannenberg A.; Razzaq R.; Jackstell R.; et al. Methyl formate as a hydrogen energy carrier. Nat. Catal. 2023, 6 (6), 543–550. 10.1038/s41929-023-00959-8. - DOI