Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Zirconia-Supported Vanadium Oxide Catalysts for Ammoxidation and Oxidation of Toluene: A Characterization and Activity Study

In English

Författare

Summary, in English

A series of samples of vanadia supported on monoclinic zirconia were prepared with nominal loadings from a half up to sixteen theoretical vanadia layers. The samples were characterized with X-ray diffraction, scanning electron microscopy combined with energy dispersive X-ray analysis, high-resolution electron microscopy, Raman and diffuse reflectance infrared spectroscopy, and were used in the oxidation and the ammoxidation of toluene. At loadings in the monolayer range, Raman and infrared bands from decavanadate-like and dehydrated tetrahedral vanadia species were at ca. 990 and ca. 1025 cm−1, respectively. Raman bands at 821 and 880 cm−1 were present only at the lowest loading and are characteristic of orthovanadate and pyrovanadate species, respectively. X-ray diffraction, Raman and infrared spectroscopic results revealed formation of some crystalline V2O5 and ZrV2O7 at loadings exceeding a theoretical monolayer. In this case, consideration of Raman intensity variations allowed the conclusion that additional non-crystalline vanadia must be present. According to high-resolution electron micrographs, this vanadia consists of an amorphous overlayer, 4–8 atomic layers thick. In toluene oxidation zirconia-supported vanadia compared with crystalline V2O5 was found less selective for benzaldehyde formation. In toluene ammoxidation, on the other hand, vanadia on zirconia was found to possess good activity and selectivity for benzonitrile formation. Amorphous vanadia was the most active structure on zirconia, while the selectivities for nitrile and aldehyde formations were almost independent of the loading for one theoretical layer and above.

Publiceringsår

1993

Språk

Engelska

Sidor

51-72

Publikation/Tidskrift/Serie

Applied Catalysis A: General

Volym

106

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Chemical Engineering
  • Production Engineering, Human Work Science and Ergonomics

Nyckelord

  • catalyst characterization (BET/XRD/DRIFTS/FT-Raman spectroscopy/EDX/SEM / HREM)
  • toluene oxidation
  • toluene ammoxidation
  • vanadie-zirconia
  • zirconia (monoclinic)

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0926-860X