Stability of Iron-Molybdate Catalysts for Selective Oxidation of Methanol to Formaldehyde: Influence of Preparation Method

  • Kristian Viegaard Raun
  • Lars Fahl Lundegaard
  • Pablo Beato
  • Charlotte Clausen Appel
  • Kenneth Nielsen
  • Max Thorhauge
  • Max Schumann
  • Anker Degn Jensen
  • Jan-Dierk Grunwaldt
  • Martin HøjEmail author


Iron molybdate/molybdenum oxide catalysts with varying content of Mo (Mo/Fe = 1.6 and 2.0) were synthesized by a mild hydrothermal method and structurally characterized by XRD, XPS, Raman spectroscopy, SEM–EDX, BET and ICP-OES. The stability of the prepared catalysts in selective oxidation of methanol to formaldehyde was investigated by catalytic activity measurements for up to 100 h on stream in a laboratory fixed-bed reactor (5% MeOH, 10% O2 in N2, temp. = 380–407 °C). Excess MoO3 present in the catalyst volatilized under reaction conditions, which lead to an initial loss of activity. Interestingly, the structure of the excess MoO3 significantly affected the stability of the catalyst. By using low temperature hydrothermal synthesis, catalysts with the thermodynamically metastable hexagonal h-MoO3 phase was synthesized, which yielded relatively large crystals (2–10 µm), with correspondingly low surface area to volume ratio. The rate of volatilization of MoO3 from these crystals was comparatively low, which stabilized the catalysts. It was furthermore shown that heat-treatment of a spent catalyst, subject to significant depletion of MoO3, reactivated the catalyst, likely due to migration of Mo from the bulk of the iron molybdate crystals to the surface region.

Graphical Abstract

Fe2(MoO4)3/MoO3 catalysts for selective oxidation of methanol were synthesized by hydrothermal synthesis forming large hexagonal-MoO3 crystals. Significantly lower rate of catalyst deactivation due to volatilization of MoO3 under reaction conditions was observed for the large h-MoO3 compared to smaller crystals of thermodynamically stable α-MoO3.


Formox Formaldehyde Iron molybdate Hexagonal MoO3 Catalyst deactivation 



This work is a collaboration between the CHEC research center at The Department of Chemical and Biochemical Engineering at Technical University of Denmark (DTU), Karlsruhe Institute of Technology (KIT) and Haldor Topsøe A/S. We thank the Independent Research Fund Denmark for the financial support (DFF—4184-00336).

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.

Supplementary material

10562_2019_3034_MOESM1_ESM.docx (1.8 mb)
Supplementary material 1 Activity, selectivity and carbon mole balance measurements, reference Raman spectra, Arrhenius plots, SEM images of sample FeMo_2.0h and FeMo_2.0α, XPS spectra and operando Raman spectra for the FeMo_2.0h sample. (DOCX 1822 kb)


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Kristian Viegaard Raun
    • 1
  • Lars Fahl Lundegaard
    • 2
  • Pablo Beato
    • 2
  • Charlotte Clausen Appel
    • 2
  • Kenneth Nielsen
    • 3
  • Max Thorhauge
    • 2
  • Max Schumann
    • 1
  • Anker Degn Jensen
    • 1
  • Jan-Dierk Grunwaldt
    • 4
  • Martin Høj
    • 1
    Email author
  1. 1.Department of Chemical and Biochemical EngineeringTechnical University of Denmark (DTU)Kgs. LyngbyDenmark
  2. 2.Haldor Topsøe A/SKgs. LyngbyDenmark
  3. 3.Department of PhysicsTechnical University of Denmark (DTU)Kgs. LyngbyDenmark
  4. 4.Institute for Chemical Technology and Polymer ChemistryKarlsruhe Institute of Technology (KIT)KarlsruheGermany

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