A potassium tert-butoxide and hydrosilane system for ultra-deep desulfurization of fuels

Abstract

Hydrodesulfurization (HDS) is the process by which sulfur-containing impurities are removed from petroleum streams, typically using a heterogeneous, sulfided transition metal catalyst under high H2 pressures and temperatures. Although generally effective, a major obstacle that remains is the desulfurization of highly refractory sulfur-containing heterocycles, such as 4,6-dimethyldibenzothiophene (4,6-Me2DBT), which are naturally occurring in fossil fuels. Homogeneous HDS strategies using well-defined molecular catalysts have been designed to target these recalcitrant S-heterocycles; however, the formation of stable transition metal sulfide complexes following C–S bond activation has largely prevented catalytic turnover. Here we show that a robust potassium (K) alkoxide (O)/hydrosilane (Si)-based (‘KOSi’) system efficiently desulfurizes refractory sulfur heterocycles. Subjecting sulfur-rich diesel (that is, [S] 10,000 ppm) to KOSi conditions results in a fuel with [S] 2 ppm, surpassing ambitious future governmental regulatory goals set for fuel sulfur content in all countries.

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Figure 1: Strategies for the hydrodesulfurization of petroleum streams and model compounds.
Figure 2: Reductive cleavage of C–X bonds by the KOSi system.
Figure 3: Free energy profile for KOSi processes.
Figure 4: Proposed mechanism for hydrodesulfurization (HDS) of dibenzothiophenes and hydrogenative cleavage of diarylethers by KOSi.

References

  1. 1

    Stirling, D. The Sulfur Problem: Cleaning up Industrial Feedstocks (ed. Clark, J. H. ) (RSC Clean Technology Monographs, RSC, 2000).

    Google Scholar 

  2. 2

    Ho, T. C. Deep HDS of diesel fuel: chemistry and catalysis. Catal. Today 98, 3–18 (2004).

    Article  Google Scholar 

  3. 3

    Angelici, R. J. Hydrodesulfurization & Hydrodenitrogenation (Encyclopedia of Inorganic Chemistry, Wiley, 2006); http://doi.org/10.1002/0470862106.ia090

    Google Scholar 

  4. 4

    Prins, R. et al. Mechanisms of hydrodesulfurization and hydrodenitrogenation. Catal. Today 111, 84–93 (2006).

    Article  Google Scholar 

  5. 5

    Girgis, M. J. & Gates, B. C. Reactivities, reaction networks, and kinetics in high-pressure catalytic hydroprocessing. Ind. Eng. Chem. Res. 30, 2021–2058 (1991).

    Article  Google Scholar 

  6. 6

    Vicic, D. A. & Jones, W. D. Deep hydrodesulfurization in homogeneous solution: access to a transition-metal insertion complex of 4,6-dimethyldibenzothiophene. Organometallics 17, 3411–3413 (1998).

    Article  Google Scholar 

  7. 7

    Vicic, D. A. & Jones, W. D. Modeling the hydrodesulfurization reaction at nickel. Unusual reactivity of dibenzothiophenes relative to thiophene and benzothiophene. J. Am. Chem. Soc. 121, 7606–7617 (1999).

    Article  Google Scholar 

  8. 8

    Sattler, A. & Parkin, G. Carbon–sulfur bond cleavage and hydrodesulfurization of thiophenes by tungsten. J. Am. Chem. Soc. 133, 3748–3751 (2011).

    Article  Google Scholar 

  9. 9

    Sattler, A., Janak, K. E. & Parkin, G. Modeling aspects of hydrodesulfurization by molybdenum hydride compounds: desulfurization of thiophene and benzothiophene and C–S bond cleavage of dibenzothiophene. Inorg. Chim. Acta 369, 197–202 (2011).

    Article  Google Scholar 

  10. 10

    Lin, S., Herbert, D. E., Velian, A., Day, M. W. & Agapie, T. Dipalladium(I) terphenyl diphosphine complexes as models for two-site adsorption and activation of organic molecules. J. Am. Chem. Soc. 135, 15830–15840 (2013).

    Article  Google Scholar 

  11. 11

    Hirotsu, M., Tsuboi, C., Nishioka, T. & Kinoshita, I. Carbon–sulfur bond cleavage reactions of dibenzothiophene derivatives mediated by iron and ruthenium carbonyls. Dalton Trans. 40, 785–787 (2011).

    Article  Google Scholar 

  12. 12

    Oster, S. S., Grochowski, M. R., Lachicotte, R. J., Brennessel, W. W. & Jones, W. D. Carbon-sulfur bond activation of dibenzothiophenes and phenoxythiin by [Rh(dippe)(𝜇-H)]2 and [Rh2(dippe)2(𝜇-Cl)(𝜇-H)]. Organometallics 29, 4923–4931 (2010).

    Article  Google Scholar 

  13. 13

    Furimsky, E. & Massoth, F. E. Regeneration of hydroprocessing catalysts. Catal. Today 17, 537–660 (1993).

    Article  Google Scholar 

  14. 14

    Torres-Nieto, J., Arévalo, A., García-Gutiérrez, P., Acosta-Ramíez, A. & García, J. J. Catalytic desulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene with nickel compounds. Organometallics 23, 4534–4536 (2004).

    Article  Google Scholar 

  15. 15

    Bunquin, J. C. & Stryker, J. M. Transition metal catalysts for hydrodesulfurization. US patent US20140174989 A1 (2014).

  16. 16

    Sunyer, J. et al. The association of daily sulfur dioxide air pollution levels with hospital admissions for cardiovascular diseases in Europe (The Aphea-II study). Eur. Heart J. 24, 752–760 (2003).

    Article  Google Scholar 

  17. 17

    Fedorov, A., Toutov, A. A., Swisher, N. A. & Grubbs, R. H. Lewis-base silane activation: from reductive cleavage of aryl ethers to selective ortho-silylation. Chem. Sci. 4, 1640–1645 (2013).

    Article  Google Scholar 

  18. 18

    Buccella, D. & Janak, K. E. Reactivity of Mo(PMe3)6 towards benzothiophene and selenophenes: new pathways relevant to hydrodesulfurization. J. Am. Chem. Soc. 130, 16187–16189 (2008).

    Article  Google Scholar 

  19. 19

    Bianchini, C., Meli, A. & Vizza, F. Role of single-site catalysts in the hydrogenation of thiophenes: from models systems to effective HDS catalysts. J. Organomet. Chem. 689, 4277–4290 (2004).

    Article  Google Scholar 

  20. 20

    Chehata, A., Oviedo, A., Arévalo, A., Bernès, S. & García, J. J. Reactivity of [Ru3(CO)12] with dibenzothiophene, methylbenzothiophene, and methyldibenzothiophene. Organometallics 22, 1585–1587 (2003).

    Article  Google Scholar 

  21. 21

    Garcia, J. J. & Maitlis, P. Hydrodesulfurization of dibenzothiophene into biphenyl by tris(triethylphosphine)platinum(0). J. Am. Chem. Soc. 115, 12200–12201 (1993).

    Article  Google Scholar 

  22. 22

    Ma, X., Sakanishi, K. & Mochida, I. Hydrodesulfurization reactivities of various sulfur compounds in diesel fuel. Ind. Eng. Chem. Res. 33, 218–222 (1994).

    Article  Google Scholar 

  23. 23

    Wang, L., He, W. & Yu, Z. Transition-metal mediated carbon–sulfur bond activation and transformations. Chem. Soc. Rev. 42, 599–621 (2013).

    Article  Google Scholar 

  24. 24

    Lawrence, N. J., Drew, M. D. & Bushell, S. M. Polymethylhydrosiloxane: a versatile reducing agent for organic synthesis. J. Chem. Soc. 1, 3381–3391 (1999).

    Google Scholar 

  25. 25

    Toutov, A. A. et al. Silylation of C–H bonds in aromatic heterocycles by an Earth-abundant metal catalyst. Nature 518, 80–85 (2015).

    Article  Google Scholar 

  26. 26

    Toutov, A. A., Liu, W.-B., Betz, K. N., Stoltz, B. M. & Grubbs, R. H. Catalytic C–H bond silylation of aromatic heterocycles. Nat. Protoc. 10, 1897–1903 (2015).

    Article  Google Scholar 

  27. 27

    Postigo, A., Kopsov, S., Zlotsky, S. S., Ferreri, C. & Chatgilialoglu, C. Hydrosilylation of C–C multiple bonds using (Me3Si)3SiH in water. Comparative study of the radical initiation step. Organometallics 28, 3282–3287 (2009).

    Article  Google Scholar 

  28. 28

    Barham, J. P. et al. KOtBu: a privileged reagent for electron transfer reactions? J. Am. Chem. Soc. 138, 7402–7410 (2016).

    Article  Google Scholar 

  29. 29

    Studer, A. & Curran, D. P. Organocatalysis and C–H activation meet radical- and electron-transfer reactions. Angew. Chem. Int. Ed. 50, 5018–5022 (2011).

    Article  Google Scholar 

  30. 30

    Studer, A. & Curran, D. P. The electron is a catalyst. Nat. Chem. 6, 765–773 (2014).

    Article  Google Scholar 

  31. 31

    Fukumoto, K., Sakai, A., Oya, T. & Nakazawa, H. Desulfurization of N,N-dimethylthioformamide by hydrosilane with the help of an iron complex. Isolation and characterization of an iron–carbene complex as an intermediate of C =S double bond cleavage. Chem. Commun. 48, 3809–3811 (2012).

    Article  Google Scholar 

  32. 32

    Kukula, P., Dutly, A., Rüegger, H. & Prins, R. Molecular rearrangement in the Birch reduction of dibenzothiophenes. Tetrahedron Lett. 48, 5657–5659 (2007).

    Article  Google Scholar 

  33. 33

    Pangborn, A. M., Giardello, M. A., Grubbs, R. H., Rosen, R. K. & Timmers, F. J. Safe and convenient procedure for solvent purification. Organometallics 15, 1518–1520 (1996).

    Article  Google Scholar 

  34. 34

    Frisch, M. J. et al. Gaussian 09 Revision D.01 (Gaussian Inc., 2013).

  35. 35

    Becke, A. D. Density functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98, 5648–5652 (1993).

    Article  Google Scholar 

  36. 36

    Ditchfield, R., Hehre, W. J. & Pople, J. A. Self-consistent molecular-orbital methods. IX. An extended Gaussian-type basis for molecular-orbital studies of organic molecules. J. Chem. Phys. 54, 724–728 (1971).

    Article  Google Scholar 

  37. 37

    Zhao, Y. & Truhlar, D. G. Density functionals with broad applicability in chemistry. Acc. Chem. Res. 41, 157–167 (2008).

    Article  Google Scholar 

  38. 38

    Legault, C. Y. CYLview 1.0b (Université de Sherbrooke, 2009); http://www.cylview.org

Download references

Acknowledgements

Support of this work by BP under the XC2 program is gratefully acknowledged. A.A.T. is additionally grateful to the Resnick Sustainability Institute at Caltech, Dow Chemical, and Bristol–Myers Squibb for predoctoral fellowships, and to NSERC for a PGS D fellowship. K.N.H. is grateful to the US National Science Foundation (CHE-1205646 and CHE-1361104) for financial support and to the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the US National Science Foundation (OCI-1053575). Y.L. thanks the ‘National Thousand Young Talents Program’ and ‘Jiangsu Specially-Appointed Professor Plan’ in China for financial support. E.P.A.C. thanks K. Lammertsma (Division of Organic Chemistry, Vrije Universiteit Amsterdam, The Netherlands) for access to, and SURFsara (www.surfsara.nl) for their support in using the Lisa Computer Cluster. G. Huff, G. Sunley, D. Braden, P. Metelski, M. Pinderski, E. Doskocil, A. Lucy, C. Buda, A. Dinse, R. Taylor, J. Bercaw, J. Labinger, M. Howard, M. Desmond, J. Elks, D. Leitch and F. Bell are gratefully thanked for technical contributions and/or invaluable discussion.

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A.A.T., A.F. and R.H.G. had the idea and designed experiments with M.S., J.W.S., R.C. and K.N.B. A.A.T., M.S., A.F. and K.N.B. performed experiments and analysed data. Y.-F.Y., Y.L., E.P.A.C. and K.N.H. designed, performed, analysed, and interpreted density functional theory calculations. A.A.T., A.F., M.S., K.N.B. and E.P.A.C. wrote the manuscript with contributions from all authors. All authors contributed to discussions.

Corresponding authors

Correspondence to John W. Shabaker or Kendall N. Houk or Robert H. Grubbs.

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Competing interests

A company commercializing the technology reported in this paper is being founded and one of the authors (A.A.T.) will be a co-founder. The other authors declare no competing interests.

Supplementary information

Supplementary Information

Supplementary Notes 1–7, Supplementary Figures 1–7, Supplementary Table 1. (PDF 1014 kb)

Supplementary Data 1

Cartesian coordinates of calculated structures. (XLSX 60 kb)

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Toutov, A., Salata, M., Fedorov, A. et al. A potassium tert-butoxide and hydrosilane system for ultra-deep desulfurization of fuels. Nat Energy 2, 17008 (2017). https://doi.org/10.1038/nenergy.2017.8

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