# Operando Ru and Ti K‐Edge X‐Ray Absorption Study of the Low‐Temperature Sabatier Reaction on Ru/TiO2 Catalysts

## TL;DR

This study uses advanced X-ray techniques to observe how a high-temperature treatment affects the structure and performance of a catalyst used in a key chemical reaction.

## Contribution

The study reveals dynamic structural and chemical changes in Ru/TiO2 catalysts during the Sabatier reaction using operando X-ray absorption spectroscopy.

## Key findings

- Reduction of Ru nanoparticles occurs faster in CO-containing gas mixtures compared to CO-free ones.
- XAS at the Ti K-edge provides insights into oxygen vacancies and the oxidation state of the support.
- Catalyst activation times correlate with the observed structural changes under reaction conditions.

## Abstract

Stimulated by recent findings of a beneficial effect of a high‐temperature treatment on the activity and selectivity of highly active and selective Ru/TiO2 catalysts in the CO
x
methanation, a detailed study of the dynamic changes in the chemical and structural properties is performed, induced by this treatment and their correlation with the changes in the catalytic performance of the catalyst. These changes are characterized by time‐resolved operando X‐ray absorption spectroscopy at the Ru and Ti K‐edges, together with structural characterization by high‐resolution transmission electron microscopy. The observation of differently long times required for the reduction of the oxidic Ru nanoparticles in CO‐free CO2/H2 gas mixtures (1000 min) and in trace amounts of CO containing CO/CO2/H2 gas mixtures (100 min) under reaction conditions (190 °C, atmospheric pressure) correlates very well with the different times required for catalyst activation in these reaction gas mixtures.

Operando X‐ray absorption spectroscopy (XAS) was used to characterize Ru/TiO2 nanoparticle catalysts in the COx methanation reaction. Near‐edge XAS at the Ru K‐edge offers access to the oxidation state of the Ru nanoparticles at different reaction stages, the Ti K‐pre‐edge region provides information on the number of O‐vacancies/the oxidation state of the support. Structural information is obtained from the extended fine structure.© 2026 WILEY‐VCH GmbH