Morphology and Activity of Electrolytic Silver Catalyst for Partial Oxidation of Methanol to Formaldehyde Under Different Exposures and Oxidation Reactions

  • S. Lervold
  • K. Arnesen
  • N. Beck
  • R. Lødeng
  • J. Yang
  • K. Bingen
  • J. Skjelstad
  • H. J. VenvikEmail author
Original Paper


Electrolytic silver particles were studied in relation to its morphology changes under different reactive and non-reactive atmospheres, and its catalytic activity in oxidation of methanol to formaldehyde (MTF), carbon monoxide to carbon dioxide, and hydrogen to water. Scanning electron microscopy and X-ray diffraction (XRD) were applied to analyze structural changes in the silver catalyst after exposure or interaction with nitrogen, oxygen, methanol/water, carbon monoxide and hydrogen, applied either individually or in selected combinations, at temperatures approaching 700 °C. The as-received Ag catalyst consists of agglomerated, faceted, polycrystalline particles. These undergo massive morphological changes during MTF reaction conditions. It was found that Ag catalysts exposed to oxygen-free atmospheres (N2, H2/N2 and CH3OH/H2O/N2) at 650 °C exhibit minimal changes in surface morphology compared to the fresh catalyst, while severe restructuring occurs on the mesoscopic scale under oxygen containing atmospheres (O2/N2, H2/O2/N2 and CO/O2/N2) at elevated temperature. This restructuring renders a smoothened surface with refacetted areas and many pinholes, while a small primary crystallite size (~ 40 nm, XRD) is maintained. Such pinholes are commonly described as a result of sub-surface oxygen/hydrogen/hydroxyl interactions. Here, they are present in all samples exposed to oxygen, indicating that presence of hydrogen is not prerequisite. For the CO and H2 oxidation sub-systems, the initial activity was comparable. But, while the conversion of H2 is preserved during 70 h time on stream, the CO conversion gradually reduces from 70 to 10%. This suggests that the restructuring associated with dissolution of O at high temperature inhibits the CO to CO2 pathway.


Electrolytic silver catalyst Formaldehyde Surface morphology CO oxidation H2 oxidation 



We gratefully acknowledge discussions with Terje Pedersen at K.A. Rasmussen AS. This publication forms a part of the iCSI (industrial Catalysis Science and Innovation) Centre for Research-based Innovation, which receives financial support from the Research Council of Norway under Contract No. 237922.

Supplementary material

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Supplementary material 1 (PDF 172 KB)


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

Authors and Affiliations

  1. 1.Department of Chemical EngineeringNTNU - Norwegian University of Science and TechnologyTrondheimNorway
  2. 2.Karlsruhe Institute of TechnologyKarlsruheGermany
  3. 3.SINTEF IndustryTrondheimNorway
  4. 4.Dynea ASLillestrømNorway
  5. 5.K.A. Rasmussen ASHamarNorway

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