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Journal of Sol-Gel Science and Technology

, Volume 19, Issue 1–3, pp 817–819 | Cite as

Study of Acidity of Aerogels ZrO2-SO42− by Isopropanol Dehydration Reaction, Surface Potential and X-Ray Photoelectron Spectroscopy

  • M.K. Younes
  • A. Ghorbel
  • A. Rives
  • R. Hubaut
Article

Abstract

Sulphated zirconia aerogels, with definite atomic ratio S/Zr and hydrolysis ratio (H = H2O/Zr) were prepared by the autoclave method. The addition of sulphate ions causes a decrease of the cristallinity of zirconia. XPS results show the O1s photoelectronpeak which could be decomposed in two components for the reticular oxygen of the zirconia framework and for oxygen attributed to the OH groups and/or sulphates groups, and the S2p photopeak characteristic of sulphates species. The Kelvin probe shows that the value of pure zirconia is around 200 mV. This value grows up to 1200 mV for sulphate doped catalysts. The modification of the work function is probably due to the charge transfer from the zirconium to an oxygen species, responsible for the increase of Lewis acidity. The catalysts prepared with hydrolysis ratio of H = 4 exhibit higher activities in the isopropanol dehydration reaction than those with H = 2 in the temperature range 373 K–423 K.

aerogel sulphated zirconia hydrolysis isopropanol dehydration 

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Copyright information

© Kluwer Academic Publishers 2000

Authors and Affiliations

  • M.K. Younes
    • 1
  • A. Ghorbel
    • 1
  • A. Rives
    • 2
  • R. Hubaut
    • 2
  1. 1.Faculté des Sciences de Tunis, Département de ChimieLaboratoire de Chimie des Matériaux etCatalyseTunisia
  2. 2.Laboratoire de Catalyse Homogène et Hétérogène, URA CNRS 402Université des Sciences et TechnologiesVilleneuve d'AscqFrance

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