# Role of Oxygen Vacancies in Fe/Ru-Based Catalysts for the Reverse Water Gas Shift Reaction: Performance and Characterization

## TL;DR

This study explores how Fe/Ru-based catalysts with oxygen vacancies can efficiently convert CO2 into CO at lower temperatures, offering a cost-effective solution for CO2 utilization.

## Contribution

The novel contribution is identifying a 75% Fe-25% Ru catalyst on Ce-doped Al2O3 that optimizes CO2 conversion and stability through enhanced metal-support interactions.

## Key findings

- A 75% Fe-25% Ru catalyst on Ce-doped Al2O3 showed optimal CO2 conversion and CO selectivity.
- Oxygen vacancies and metal-support interactions significantly influence catalytic performance at lower temperatures.
- The catalyst maintained stability under repeated temperature cycles up to 800 °C.

## Abstract

The Reverse Water–Gas
Shift (RWGS) reaction is a key process
for converting carbon dioxide (CO2) into carbon monoxide
(CO), enabling downstream synthesis of fuels and chemicals while contributing
to CO2 emissions mitigation. This study investigates the
performance of several Fe
x
-Ru
y
-based catalysts supported on different doped oxide
materials (La–Al2O3, Ce–Al2O3, Sm-CeO2, Si–Al2O3), with the goal of identifying a cost-effective and
thermally stable alternative to purely noble metal systems. Catalysts
were evaluated in atmospheric conditions up to 800 °C and subjected
to repeated temperature ramp cycles to assess CO2 conversion,
CO selectivity, and long-term stability. Comprehensive characterization
was performed using ICP-OES, BET, TPR, XRD, HRTEM, and XPS. The results
reveal that optimizing the strength of the metal–support interaction,
as well as the active metals ratio can have a significant impact,
in terms of available active sites, which influences the catalytic
performance, especially at lower temperatures (<500 °C). It
was found that a ratio of 75% Fe and 25% Ru on Ce-doped Al2O3 provided this balance of properties. These findings
provide insight into the design of robust, economically viable RWGS
catalysts for efficient CO2 utilization.