Volume 229, 2021

Insight into the mechanism of the water–gas shift reaction over Au/CeO2 catalysts using combined operando spectroscopies

Abstract

The mechanism of the low-temperature water–gas shift (LT-WGS) reaction over Au/CeO2 catalysts with different ceria terminations, i.e., (111), (110), and (100) facets, was investigated. Using combined operando Raman and UV-Vis spectroscopy as well as isotope exchange experiments, we are able to draw conclusions about the reducibility behaviour and the exchange of surface oxygen. Additional density functional theory (DFT) calculations facilitate the vibrational bands assignments and enhance the interpretation of the results on a molecular level. A facet-dependent role of gold is observed with respect to the oxygen dynamics, since for the CeO2(111) facet the presence of gold is required to exchange surface oxygen, whereas the CeO2(110) facet requires no gold, as rationalized by the low defect formation energy of this facet. This behaviour suggests that surface properties (termination, stepped surface) may have a strong effect on the reactivity. While the reduction of the support accompanies the reaction, its extent does not directly correlate with activity, highlighting the importance of other properties, such as the dissociative adsorption of water and/or CO2/H2 desorption. The results of our facet-dependent study are consistent with a redox mechanism, as underlined by H218O isotopic exchange experiments demonstrating the ready exchange of surface oxygen.

Graphical abstract: Insight into the mechanism of the water–gas shift reaction over Au/CeO2 catalysts using combined operando spectroscopies

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
09 dic. 2019
Accepted
22 ene. 2020
First published
22 ene. 2020

Faraday Discuss., 2021,229, 232-250

Insight into the mechanism of the water–gas shift reaction over Au/CeO2 catalysts using combined operando spectroscopies

M. Ziemba, M. V. Ganduglia-Pirovano and C. Hess, Faraday Discuss., 2021, 229, 232 DOI: 10.1039/C9FD00133F

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