Vanadium Oxide on TiO2(B) - a HREM Study of Catalysis by Support Interaction

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Abstract

A model catalyst system with a loading range between 1/4 to 10 theoretical layers of vanadium oxide on TiO2(B ) support was tried for selective ammoxidation and oxidation of toluene. In the case of ammoxidation, a peak in conversion rate per unit surface area was found for a catalyst with a coverage of about 2 theoretical layers, indicating a strong interaction between the catalyst and the otherwise inactive support. The presence and amount of vanadium oxide on the support surface was verified by diffuse reflectance infrared spectroscopy, energy-dispersive elemental X-ray mapping and chemical analysis. By high resolution electron microscopy, the 32~ volume loss of the K2Ti409 support precursor on calcination was shown to be achieved by formation of microscopic, facetted voids ("negative crystals") in the bulk of the material. Initially, surfaces appeared dean and without any anomalous surface features. This can be explained by similar scattering power of V and Ti, and similar structure types. However, the active phase could be "developed" to visibility by prolonged exposure to the electron beam, which produced 1-2 am particles of reduced vanadium oxides on the surface.

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Subject classification (UKÄ) – MANDATORY

  • Chemical Sciences
  • Chemical Engineering
  • Production Engineering, Human Work Science and Ergonomics
Original languageEnglish
Pages (from-to)33-40
JournalUltramicroscopy
Volume34
Issue number1-2
Publication statusPublished - 1990
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Ergonomics and Aerosol Technology (011025002), Chemical Engineering (011001014), Polymer and Materials Chemistry (LTH) (011001041)