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Title: Systematic study on the influence of the morphology of α-MoO{sub 3} in the selective oxidation of propylene

A variety of morphologically different α-MoO{sub 3} samples were prepared by hydrothermal synthesis and applied in the selective oxidation of propylene. Their catalytic performance was compared to α-MoO{sub 3} 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-MoO{sub 3} after calcination at 550 °C. A one-step synthesis of α-MoO{sub 3} rods was possible starting from MoO{sub 3}·2H{sub 2}O 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. - Graphical abstract: Hydrothermal synthesis from MoO{sub 3}·2H{sub 2}O in the presence of HNO{sub 3} led to rod-shaped particles which mainly expose (1 0 0) facets which are the most activemore » surfaces. - Highlights: • Hydrothermal synthesis of MoO3 resulted in either rod or slab shaped particles depending on pH. • At pH<0 rods stable towards calcination and catalytic activity testing were formed. • Rod shaped particles had significantly higher activity than slab shaped ones. • The rod shaped particles mainly expose the (1 0 0) facets which are the most active surfaces. • Total surface area is not main determining factor for catalytic activity.« less
Authors:
;  [1] ; ;  [2] ;  [3] ;  [4] ;  [1]
  1. Karlsruhe Institute of Technology (KIT), Institute for Chemical Technology and Polymer Chemistry (ITCP) and Institute of Catalysis Research and Technology - IKFT, Engesserstr. 20, D-76131 Karlsruhe (Germany)
  2. Technical University of Denmark (DTU), Department of Chemical & Biochemical Engineering, Søltofts Plads, DK-2800 Kgs. Lyngby (Denmark)
  3. Haldor Topsøe A/S, Nymøllevej 55, DK-2800 Kgs. Lyngby (Denmark)
  4. University of Zurich (UZH), Department of Chemistry, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)
Publication Date:
OSTI Identifier:
22486719
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 228; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACETIC ACID; CALCINATION; HYDRATES; HYDROTHERMAL SYNTHESIS; MOLYBDENUM OXIDES; MORPHOLOGY; NITRIC ACID; OXIDATION; PH VALUE; PROPYLENE; RAMAN SPECTROSCOPY; SCANNING ELECTRON MICROSCOPY; SPRAYS; SURFACE AREA; X-RAY DIFFRACTION