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Operando NAP-XPS unveils differences in MoO3 and Mo2C during hydrodeoxygenation


MoO3 and Mo2C have emerged as remarkable catalysts for the selective hydrodeoxygenation (HDO) of a wide range of oxygenates at low temperatures (that is, ≤673 K) and H2 pressures (that is, ≤1 bar). Although both catalysts can selectively cleave C–O bonds, the nature of their active sites remains unclear. Here we used operando near-ambient pressure X-ray photoelectron spectroscopy to reveal important differences in the Mo 3d oxidation states between the two catalysts during the hydrodeoxygenation of anisole. This technique revealed that, although both catalysts featured a surface oxycarbidic phase, the oxygen content and the underlying phase of the material impacted the reactivity and product selectivity during the hydrodeoxygenation. MoO3 transitioned between 5+ and 6+ oxidation states during the operation, consistent with an oxygen-vacancy driven mechanism wherein the oxygenate is activated at undercoordinated Mo sites. In contrast, Mo2C showed negligible oxidation state changes during hydrodeoxygenation and maintained mostly 2+ states throughout the reaction.

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Fig. 1: NAP-XPS of prereduced MoO3 during the HDO of anisole at a photon energy of 473 eV.
Fig. 2: NAP-XPS of Mo2C during the HDO of anisole at a photon energy of 473 eV.
Fig. 3: Normalized Mo 3d spectra of Mo2C-pass during the HDO of anisole measured at a photon energy of 473 eV.

Data availability

All data are available from the corresponding author upon reasonable request.


  1. 1.

    Furimsky, E. Catalytic hydrodeoxygenation. Appl. Catal. A 199, 147–190 (2000).

    CAS  Article  Google Scholar 

  2. 2.

    Huber, G. W., Iborra, S. & Corma, A. Synthesis of transportation fuels from biomass: chemistry, catalysts, and engineering. Chem. Rev. 106, 4044–4098 (2006).

    CAS  Article  PubMed  Google Scholar 

  3. 3.

    Choudhary, T. & Phillips, C. Renewable fuels via catalytic hydrodeoxygenation. Appl. Catal. A 397, 1–12 (2011).

    CAS  Article  Google Scholar 

  4. 4.

    Bu, Q. et al. A review of catalytic hydrodeoxygenation of lignin-derived phenols from biomass pyrolysis. Bioresour. Technol. 124, 470–477 (2012).

    CAS  Article  PubMed  Google Scholar 

  5. 5.

    He, Z. & Wang, X. Hydrodeoxygenation of model compounds and catalytic systems for pyrolysis bio-oils upgrading. Catal. Sustainable Energy 1, 28–52 (2012).

    Google Scholar 

  6. 6.

    Ruddy, D. A. et al. Recent advances in heterogeneous catalysts for bio-oil upgrading via ‘ex situ catalytic fast pyrolysis’: catalyst development through the study of model compounds. Green Chem. 16, 454–490 (2014).

    CAS  Article  Google Scholar 

  7. 7.

    Tran, N., Uemura, Y., Chowdhury, S. & Ramli, A. A review of bio-oil upgrading by catalytic hydrodeoxygenation. Appl. Mech. Mater. 625, 255–258 (2014).

    CAS  Article  Google Scholar 

  8. 8.

    Saidi, M. et al. Upgrading of lignin-derived bio-oils by catalytic hydrodeoxygenation. Energy Environ. Sci. 7, 103–129 (2014).

    CAS  Article  Google Scholar 

  9. 9.

    Schutyser, W. et al. Influence of bio-based solvents on the catalytic reductive fractionation of birch wood. Green Chem. 17, 5035–5045 (2015).

    CAS  Article  Google Scholar 

  10. 10.

    Anderson, E. M. et al. Reductive catalytic Fractionation of corn stover lignin. ACS Sustainable Chem. Eng. 4, 6940–6950 (2016).

    CAS  Article  Google Scholar 

  11. 11.

    Anderson, E., Crisci, A., Murugappan, K. & Román-Leshkov, Y. Bifunctional molybdenum polyoxometalates for the combined hydrodeoxygenation and alkylation of lignin-derived model phenolics. ChemSusChem 10, 2226–2234 (2017).

    CAS  Article  PubMed  Google Scholar 

  12. 12.

    Venkatakrishnan, V. K., Delgass, W. N., Ribeiro, F. H. & Agrawal, R. Oxygen removal from intact biomass to produce liquid fuel range hydrocarbons via fast-hydropyrolysis and vapor-phase catalytic hydrodeoxygenation. Green Chem. 17, 178–183 (2015).

    CAS  Article  Google Scholar 

  13. 13.

    Anderson, E. M. et al. Flowthrough reductive catalytic fractionation of biomass. Joule 1, 613–622 (2017).

    CAS  Article  Google Scholar 

  14. 14.

    Prasomsri, T., Nimmanwudipong, T. & Román-Leshkov, Y. Effective hydrodeoxygenation of biomass-derived oxygenates into unsaturated hydrocarbons by MoO3 using low H2 pressures. Energy Environ. Sci. 6, 1732–1738 (2013).

    CAS  Article  Google Scholar 

  15. 15.

    Prasomsri, T., Shetty, M., Murugappan, K. & Román-Leshkov, Y. Insights into the catalytic activity and surface modification of MoO3 during the hydrodeoxygenation of lignin-derived model compounds into aromatic hydrocarbons under low hydrogen pressures. Energy Environ. Sci. 7, 2660–2669 (2014).

    CAS  Article  Google Scholar 

  16. 16.

    Shetty, M., Murugappan, K., Prasomsri, T., Green, W. H. & Román-Leshkov, Y. Reactivity and stability investigation of supported molybdenum oxide catalysts for the hydrodeoxygenation (HDO) of m-cresol. J. Catal. 331, 86–97 (2015).

    CAS  Article  Google Scholar 

  17. 17.

    Murugappan, K. et al. Supported molybdenum oxides as effective catalysts for the catalytic fast pyrolysis of lignocellulosic biomass. Green Chem. 18, 5548–5557 (2016).

    CAS  Article  Google Scholar 

  18. 18.

    Zhou, G., Jensen, P. A., Le, D. M., Knudsen, N. O. & Jensen, A. D. Atmospheric hydrodeoxygenation of biomass fast pyrolysis vapor by MoO3. ACS Sustainable Chem. Eng. 4, 5432–5440 (2016).

    CAS  Article  Google Scholar 

  19. 19.

    Nolte, M. W., Zhang, J. & Shanks, B. H. Ex situ hydrodeoxygenation in biomass pyrolysis using molybdenum oxide and low pressure hydrogen. Green Chem. 18, 134–138 (2016).

    Article  Google Scholar 

  20. 20.

    Shetty, M., Murugappan, K., Green, W. H. & Román-Leshkov, Y. Structural properties and reactivity trends of molybdenum oxide catalysts supported on zirconia for the hydrodeoxygenation of anisole. ACS Sustainable Chem. Eng. 5, 5293–5301 (2017).

    CAS  Article  Google Scholar 

  21. 21.

    Ren, H. et al. Selective hydrodeoxygenation of biomass-derived oxygenates to unsaturated hydrocarbons using molybdenum carbide catalysts. ChemSusChem 6, 798–801 (2013).

    CAS  Article  PubMed  Google Scholar 

  22. 22.

    Lee, W.-S., Wang, Z., Zheng, W., Vlachos, D. G. & Bhan, A. Vapor phase hydrodeoxygenation of furfural to 2-methylfuran on molybdenum carbide catalysts. Catal. Sci. Technol. 4, 2340–2352 (2014).

    CAS  Article  Google Scholar 

  23. 23.

    Xiong, K., Lee, W. S., Bhan, A. & Chen, J. G. Molybdenum carbide as a highly selective deoxygenation catalyst for converting furfural to 2‐methylfuran. ChemSusChem 7, 2146–2149 (2014).

    CAS  Article  PubMed  Google Scholar 

  24. 24.

    Xiong, K., Yu, W. & Chen, J. G. Selective deoxygenation of aldehydes and alcohols on molybdenum carbide (Mo2C) surfaces. Appl. Surf. Sci. 323, 88–95 (2014).

    CAS  Article  Google Scholar 

  25. 25.

    McManus, J. R. & Vohs, J. M. Deoxygenation of glycolaldehyde and furfural on Mo2C/Mo(100). Surf. Sci. 630, 16–21 (2014).

    CAS  Article  Google Scholar 

  26. 26.

    Lee, W.-S., Wang, Z., Wu, R. J. & Bhan, A. Selective vapor-phase hydrodeoxygenation of anisole to benzene on molybdenum carbide catalysts. J. Catal. 319, 44–53 (2014).

    CAS  Article  Google Scholar 

  27. 27.

    Lee, W.-S., Kumar, A., Wang, Z. & Bhan, A. Chemical titration and transient kinetic studies of site requirements in Mo2C-catalyzed vapor phase anisole hydrodeoxygenation. ACS Catal. 5, 4104–4114 (2015).

    CAS  Article  Google Scholar 

  28. 28.

    Chen, C.-J., Lee, W.-S. & Bhan, A. Mo2C catalyzed vapor phase hydrodeoxygenation of lignin-derived phenolic compound mixtures to aromatics under ambient pressure. Appl. Catal. A 510, 42–48 (2016).

    CAS  Article  Google Scholar 

  29. 29.

    Chen, C.-J. & Bhan, A. Mo2C Modification by CO2, H2O, and O2: effects of oxygen content and oxygen source on rates and selectivity of m-cresol hydrodeoxygenation. ACS Catal. 7, 1113–1122 (2017).

    CAS  Article  Google Scholar 

  30. 30.

    He, S., Broom, J., van der Gaast, R. & Seshan, K. Hydro-pyrolysis of lignocellulosic biomass over alumina supported platinum, Mo2C and WC catalysts. Front. Chem. Sci. Eng. 12, 155–166 (2017).

    Article  Google Scholar 

  31. 31.

    Iida, T. et al. Encapsulation of molybdenum carbide nanoclusters inside zeolite micropores enables synergistic bifunctional catalysis for anisole hydrodeoxygenation. ACS Catal. 7, 8147–8151 (2017).

    CAS  Article  Google Scholar 

  32. 32.

    Knop‐Gericke, A. et al. X‐Ray photoelectron spectroscopy for investigation of heterogeneous catalytic processes. Adv. Catal. 52, 213–272 (2009).

    Google Scholar 

  33. 33.

    Patt, J., Moon, D. J., Phillips, C. & Thompson, L. Molybdenum carbide catalysts for water–gas shift. Catal. Lett. 65, 193–195 (2000).

    CAS  Article  Google Scholar 

  34. 34.

    Sullivan, M. M., Chen, C.-J. & Bhan, A. Catalytic deoxygenation on transition metal carbide catalysts. Catal. Sci. Technol. 6, 602–616 (2016).

    CAS  Article  Google Scholar 

  35. 35.

    Choi, J.-S., Bugli, G. & Djéga-Mariadassou, G. Influence of the degree of carburization on the density of sites and hydrogenating activity of molybdenum carbides. J. Catal. 193, 238–247 (2000).

    CAS  Article  Google Scholar 

  36. 36.

    Song, Z. et al. Molecular level study of the formation and the spread of MoO3 on Au(111) by scanning tunneling microscopy and X-ray photoelectron spectroscopy. J. Am. Chem. Soc. 125, 8059–8066 (2003).

    CAS  Article  PubMed  Google Scholar 

  37. 37.

    Clayton, C. & Lu, Y. Electrochemical and XPS evidence of the aqueous formation of Mo2O5. Surf. Interface Anal. 14, 66–70 (1989).

    CAS  Article  Google Scholar 

  38. 38.

    Marin-Flores, O., Scudiero, L. & Ha, S. X-ray diffraction and photoelectron spectroscopy studies of MoO2 as catalyst for the partial oxidation of isooctane. Surf. Sci. 603, 2327–2332 (2009).

    CAS  Article  Google Scholar 

  39. 39.

    Sian, T. S. & Reddy, G. Optical, structural and photoelectron spectroscopic studies on amorphous and crystalline molybdenum oxide thin films. Sol. Energy Mater. Sol. Cells 82, 375–386 (2004).

    CAS  Article  Google Scholar 

  40. 40.

    Scanlon, D. O. et al. Theoretical and experimental study of the electronic structures of MoO3 and MoO2. J. Phys. Chem. C 114, 4636–4645 (2010).

    CAS  Article  Google Scholar 

  41. 41.

    Baltrusaitis, J. et al. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model. Appl. Surf. Sci. 326, 151–161 (2015).

    CAS  Article  Google Scholar 

  42. 42.

    Frank, B., Cotter, T. P., Schuster, M. E., Schlögl, R. & Trunschke, A. Carbon dynamics on the molybdenum carbide surface during catalytic propane dehydrogenation. Chem. Eur. J. 19, 16938–16945 (2013).

    CAS  Article  PubMed  Google Scholar 

  43. 43.

    Oshikawa, K., Nagai, M. & Omi, S. Characterization of molybdenum carbides for methane reforming by TPR, XRD, and XPS. J. Phys. Chem. B 105, 9124–9131 (2001).

    CAS  Article  Google Scholar 

  44. 44.

    Ledoux, M. J., Huu, C. P., Guille, J. & Dunlop, H. Compared activities of platinum and high specific surface area Mo2C and WC catalysts for reforming reactions: I. Catalyst activation and stabilization: reaction of n-hexane. J. Catal. 134, 383–398 (1992).

    CAS  Article  Google Scholar 

  45. 45.

    Óvári, L., Kiss, J., Farkas, A. P. & Solymosi, F. Reactivity of Mo2C/Mo(100) toward oxygen: LEIS, AES, and XPS study. Surf. Sci. 566, 1082–1086 (2004).

    Article  Google Scholar 

  46. 46.

    Clair, T. P. S. et al. Surface characterization of α-Mo2C(0001). Surf. Sci. 426, 187–198 (1999).

    Article  Google Scholar 

  47. 47.

    Sugihara, M., Ozawa, K., Edamoto, K. & Otani, S. Photoelectron spectroscopy study of Mo2C(0001). Solid State Commun. 121, 1–5 (2001).

    CAS  Article  Google Scholar 

  48. 48.

    Gao, Q., Zhao, X., Xiao, Y., Zhao, D. & Cao, M. A mild route to mesoporous Mo2C–C hybrid nanospheres for high performance lithium-ion batteries. Nanoscale 6, 6151–6157 (2014).

    CAS  Article  PubMed  Google Scholar 

  49. 49.

    Delporte, P., Pham-Huu, C., Vennegues, P., Ledoux, M. J. & Guille, J. Physical characterization of molybdenum oxycarbide catalyst; TEM, XRD and XPS. Catal. Today 23, 251–267 (1995).

    CAS  Article  Google Scholar 

  50. 50.

    Janz, G. J. Thermodynamics of the hydrogenation of benzene. J. Chem. Phys. 22, 751–752 (1954).

    CAS  Article  Google Scholar 

  51. 51.

    Baddour, F. G. et al. Late-transition-metal-modified β-Mo2C catalysts for enhanced hydrogenation during guaiacol deoxygenation. ACS Sustainable Chem. Eng. 5, 11433–11439 (2017).

    CAS  Article  Google Scholar 

  52. 52.

    Moberg, D. R., Thibodeau, T. J., Amar, F. G. & Frederick, B. G. Mechanism of hydrodeoxygenation of acrolein on a cluster model of MoO3. J. Phys. Chem. C 114, 13782–13795 (2010).

    CAS  Article  Google Scholar 

  53. 53.

    Mei, D., Karim, A. M. & Wang, Y. Density functional theory study of acetaldehyde hydrodeoxygenation on MoO3. J. Phys. Chem. C 115, 8155–8164 (2011).

    CAS  Article  Google Scholar 

  54. 54.

    Schaidle, J. A. et al. Experimental and computational investigation of acetic acid deoxygenation over oxophilic molybdenum carbide: surface chemistry and active site identity. ACS Catal. 6, 1181–1197 (2016).

    CAS  Article  Google Scholar 

  55. 55.

    Liang, J. et al. Effective conversion of heteroatomic model compounds in microalgae-based bio-oils to hydrocarbons over β-Mo2C/CNTs catalyst. J. Mol. Catal. A 411, 95–102 (2016).

    CAS  Article  Google Scholar 

  56. 56.

    Lee, J. S., Locatelli, S., Oyama, S. & Boudart, M. Molybdenum carbide catalysts 3. Turnover rates for the hydrogenolysis of n-butane. J. Catal. 125, 157–170 (1990).

    CAS  Article  Google Scholar 

  57. 57.

    Bej, S. K., Bennett, C. A. & Thompson, L. T. Acid and base characteristics of molybdenum carbide catalysts. Appl. Catal. A 250, 197–208 (2003).

    CAS  Article  Google Scholar 

  58. 58.

    Sullivan, M. M., Held, J. T. & Bhan, A. Structure and site evolution of molybdenum carbide catalysts upon exposure to oxygen. J. Catal. 326, 82–91 (2015).

    CAS  Article  Google Scholar 

  59. 59.

    Baddour, F. G., Nash, C. P., Schaidle, J. A. & Ruddy, D. A. Synthesis of α‐MoC1−x nanoparticles with a surface‐modified SBA‐15 hard template: determination of structure–function relationships in acetic acid deoxygenation. Angew. Chem. Int. Ed. 55, 9026–9029 (2016).

    CAS  Article  Google Scholar 

  60. 60.

    Powel, C. & Jablonski, A. NIST Electron Inelastic-Mean-Free-Path Database Version 1.2, SRD 71 (National Institute of Standards and Technology, Gaithersburg, 2010, accessed 24 September 2017).

  61. 61.

    Roiaz, M. et al. Reverse water–gas shift or Sabatier methanation on Ni(110)? Stable surface species at near-ambient pressure. J. Am. Chem. Soc. 138, 4146–4154 (2016).

    CAS  Article  PubMed  Google Scholar 

  62. 62.

    Plot v.0.997 (M. Wesemann & B. J. Thijsse, 2007).

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This research was funded by BP through the MIT Energy Initiative Advanced Conversion Research Program and the National Science Foundation (award no. 1454299). We thank Helmholtz-Zentrum Berlin for the allocation of synchrotron radiation beam time at the ISISS beamline of BESSY II. T.E.J. acknowledges the Alexander-von-Humboldt Foundation for financial support.

Author information




K.M. and Y.R.-L. conceived the research ideas and designed the experiments. K.M. prepared the materials and performed the PXRD. K.M., E.M.A., D.T. and K.S. performed the NAP-XPS experiments. K.M. and D.T. analysed the XPS data. T.E.J. performed the DFT calculations. K.M. and Y.R.-L. co-wrote the paper. Y.R.-L. supervised the project. All the authors discussed the results and commented on the different versions of the manuscript.

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Correspondence to Yuriy Román-Leshkov.

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Supplementary Information

Supplementary Methods; Supplementary Figures 1–58; Supplementary Tables 1-11; Supplementary References

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Murugappan, K., Anderson, E.M., Teschner, D. et al. Operando NAP-XPS unveils differences in MoO3 and Mo2C during hydrodeoxygenation. Nat Catal 1, 960–967 (2018).

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