The fate of water in hydrogen-based iron oxide reduction

TL;DR

This study uses advanced cryogenic atom probe tomography to investigate how water forms and interacts during hydrogen-based reduction of iron oxide, providing new insights into the reaction mechanisms crucial for sustainable steel production.

Contribution

It introduces a novel application of cryogenic atom probe tomography to study gas-solid reactions at the atomic level, revealing water formation dynamics during iron oxide reduction.

Findings

Water forms at specific iron-iron oxide interfaces.

Water formation kinetics are characterized in detail.

Interaction of water with redox processes is elucidated.

Abstract

Gas-solid reactions are cornerstones of many catalytic and redox processes that will underpin the energy and sustainability transition. The specific case of hydrogen-based iron oxide reduction is the foundation to render the global steel industry fossil-free, an essential target as iron production is the largest single industrial emitter of carbon dioxide. Our perception of gas-solid reactions has not only been limited by the availability of state-of-the-art techniques which can delve into the reacted solids in great structural and chemical detail, but we continue to miss an important reaction partner that defines the thermodynamics and kinetics of gas phase reactions: the gas molecules. In this investigation, we use the latest development in cryogenic atom probe tomography to study the quasi in-situ evolution of gas phase heavy water at iron-iron oxide interfaces resulting from the direct reduction of iron oxide by deuterium gas at 700{\deg}C. The findings provide new insights into the formation kinetics and location of water formed during hydrogen-based reduction of FeO, an its interaction with the ongoing redox reaction.