Systematic study on the influence of the morphology of α-MoO3 in the selective oxidation of propylene

Kirsten Schuh, Wolfgang Kleist, Martin Høj, Anker Degn Jensen, Pablo Beato, Greta R. Patzke, Jan-Dierk Grunwaldt

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Abstract

A variety of morphologically different α-MoO3 samples were prepared by hydrothermal synthesis and applied in the selective oxidation of propylene. Their catalytic performance was compared to α-MoO3 prepared by flame spray pyrolysis (FSP) and a classical synthesis route. Hydrothermal synthesis from ammonium heptamolybdate (AHM) and nitric acid at pH 1-2 led to ammonium containing molybdenum oxide phases that were completely transformed into α-MoO3 after calcination at 550 °C. A one-step synthesis of α-MoO3 rods was possible starting from MoO3·2H2O with acetic acid or nitric acid and from AHM with nitric acid at 180°C. Particularly, if nitric acid was used during synthesis, the rod-like morphology of the samples could be stabilized during calcination at 550°C and the following catalytic activity tests, which was beneficial for the catalytic performance in propylene oxidation. Characterization studies using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy showed that those samples, which retained their rod-like morphology during the activity tests, yielded the highest propylene conversion.
Original languageEnglish
JournalJournal of Solid State Chemistry
Volume228
Pages (from-to)42-52
Number of pages11
ISSN0022-4596
DOIs
Publication statusPublished - 2015

Keywords

  • Propylene oxidation
  • Molybdenum oxides
  • Morphology
  • Hydrothermal synthesis
  • Structure sensitivity

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