Issue 28, 2008

A combined theoretical–experimental study on the acidity of WOx-ZrO2 systems

Abstract

This work provides a chemical approach to the relationship between structure and electronic behavior of the active surface of the WOx-ZrO2 system as a function of W loads. This study shows that the electronic hardness (η), the Lewis and Brønsted acidity are functions of the local coordination and of the polymerization degree of the WOx domain. From theoretical calculations the observed behavior in the WOx-ZrO2 system is explained: the Brønsted acidity increases while the Lewis acidity decreases as the W centers go from tetrahedral to octahedral coordination and as the condensation degree of the WOx domain increases. Our results also indicate that not all the Brønsted sites in the WOx domains are equally acid, and that as the W load increases the most acid sites decrease in number due to the condensation process. This finding also means a decrease on the average acidity per H site. Additionally, our results suggest that for surface densities in the 4–7 W nm−2 range, mainly dimeric-tungstate species are present. A maximum in Brønsted acidity was observed for a W surface density about 7 W nm−2.

Graphical abstract: A combined theoretical–experimental study on the acidity of WOx-ZrO2 systems

Article information

Article type
Paper
Submitted
20 Feb 2008
Accepted
21 Apr 2008
First published
05 Jun 2008

Phys. Chem. Chem. Phys., 2008,10, 4181-4188

A combined theoretical–experimental study on the acidity of WOx-ZrO2 systems

A. Galano, G. Rodriguez-Gattorno and E. Torres-García, Phys. Chem. Chem. Phys., 2008, 10, 4181 DOI: 10.1039/B802934B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements