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. 2018 Jan 11;122(1):359-370.
doi: 10.1021/acs.jpcc.7b08711. Epub 2017 Nov 28.

Adsorption and Desulfurization Mechanism of Thiophene on Layered FeS(001), (011), and (111) Surfaces: A Dispersion-Corrected Density Functional Theory Study

Nelson Y Dzade  1 , Nora H de Leeuw  1   2
Affiliations

Adsorption and Desulfurization Mechanism of Thiophene on Layered FeS(001), (011), and (111) Surfaces: A Dispersion-Corrected Density Functional Theory Study

Nelson Y Dzade et al. J Phys Chem C Nanomater Interfaces. .

Abstract

Layered transition-metal chalcogenides have emerged as a fascinating new class of materials for catalysis. Here, we present periodic density functional theory (DFT) calculations of the adsorption of thiophene and the direct desulfurization reaction pathways on the (001), (011), and (111) surfaces of layered FeS. The fundamental aspects of the thiophene adsorption, including the initial adsorption geometries, adsorption energies, structural parameters, and electronic properties, are presented. From the calculated adsorption energies, we show that the flat adsorption geometries, wherein the thiophene molecule forms multiple π-bonds with the FeS surfaces, are energetically more favorable than the upright adsorption geometries, with the strength of adsorption decreasing in the order FeS(111) > FeS(011) > FeS(001). The adsorption of the thiophene onto the reactive (011) and (111) surfaces is shown to be characterized by charge transfer from the interacting Fe d-band to the π-system of the thiophene molecule, which causes changes of the intramolecular structure including loss of aromaticity and elongation of the C-S bonds. The thermodynamic and kinetic analysis of the elementary steps involved in the direct desulfurization of thiophene on the reactive FeS surfaces is also presented. Direct desulfurization of thiophene occurs preferentially on the (111) surface, as reflected by the overall exothermic reaction energy calculated for the process (ER = -0.15 eV), with an activation energy of 1.58 eV.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Layered structure of mackinawite, with the tetragonal unit cell highlighted by continuous lines. (Color scheme: Fe, gray; S, yellow.)
Figure 2
Figure 2
Geometry-optimized surface structures of the (a) FeS(001), (b) FeS(011), and (c) FeS(111) surfaces with S0, S–3, and S+3 composition. (Color scheme: Fe, gray; Ssurface, yellow; and Sadded, orange.)
Figure 3
Figure 3
Calculated surface energies of the (a) (001), (b) (011), and (c) (111) surfaces of FeS as functions of the change in sulfur chemical potential μS.
Figure 4
Figure 4
(a) Optimized structure of the thiophene molecule. The number x in Cx represents the position of the C atom in the thiophene ring. (b) The partial density of states showing the total and p-states projection on the C and S atoms.
Figure 5
Figure 5
Optimized adsorption structures of a thiophene on the nonstoichiometric (S+n) FeS surfaces fully covered with additional sulfur, in side (top) and top (bottom) views. (Color scheme: Fe, gray; Sslab, yellow; C, blue; Smolecule/added, orange.)
Figure 6
Figure 6
Optimized adsorption structures of a thiophene on stoichiometric (S0) FeS surfaces, in side (top row) and top (bottom row) views. (Color scheme: Fe, gray; Sslab, yellow; C, blue; Smolecule, orange.)
Figure 7
Figure 7
(a) Isosurface contours of the electron localization function of the thiophene–FeS(001) system and (b) the partial DOS projected on the C and S p-states of the adsorbed thiophene.
Figure 8
Figure 8
(Left) Electron density difference isosurface contours upon thiophene adsorption on the stoichiometric (011) and (111) FeS surfaces, showing regions of electron density accumulation (green) and depletion (red) by 0.02 e/Å3, respectively. (Right) Partial DOS projected on the interacting surface Fe d-states and on the C and S p-states of the adsorbed thiophene.
Figure 9
Figure 9
Reaction profile for the direct desulfurization of C4H4S on stoichiometric FeS(011). The desulfurization reaction proceeds in two steps with successive scission of the two C–S bonds.
Figure 10
Figure 10
Reaction profile for the direct desulfurization of C4H4S on stoichiometric FeS(111). The desulfurization reaction proceeds in two steps with successive scission of the two C–S bonds.
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References

    1. Knudsen K. G.; Cooper B. H.; Topsøe H. Catalyst and process technologies for ultra-low sulfur diesel. Appl. Catal., A 1999, 189, 205–215. 10.1016/S0926-860X(99)00277-X. - DOI
    1. Song C. An overview of new approaches to deep desulfurization for ultra-clean gasoline, diesel fuel and jet fuel. Catal. Today 2003, 86, 211–263. 10.1016/S0920-5861(03)00412-7. - DOI
    1. Whitehurst D. D.; Isoda T.; Mochida I. Present State of the Art and Future Challenges in the Hydrodesulfurization of Polyaromatic Sulfur Compounds. Adv. Catal. 1998, 42, 345–471. 10.1016/S0360-0564(08)60631-8. - DOI
    1. Babich I. V.; Moulijn J. A. Science and technology of novel processes for deep desulfurization of oil refinery streams: A review. Fuel 2003, 82, 607–631. 10.1016/S0016-2361(02)00324-1. - DOI
    1. Raybaud P.; Hafner J.; Kresse G.; Toulhoat H. Adsorption of thiophene on the catalytically active surface of MoS2: An ab initio local-density-functional study. Phys. Rev. Lett. 1998, 80, 1481–1484. 10.1103/PhysRevLett.80.1481. - DOI