Catalytic Oxidation Processes in Hydrogen-Rich Environments

Catalytic oxidation in hydrogen-rich streams plays a pivotal role in purifying hydrogen for fuel-cell applications, where trace amounts of carbon monoxide (CO) must be removed to prevent catalyst poisoning. The preferential oxidation (PROX) strategy targets CO in the presence of excess H₂ and O₂, ensuring high CO conversions at low temperatures while minimising H₂ consumption. Advances in bimetallic and metal-oxide catalysts, often supported on oxide or zeolitic materials, have enabled fine control over active-site structure, oxygen activation and reaction pathways. Key mechanisms include the Mars-van Krevelen route, in which lattice oxygen participates directly in oxidation, and the Langmuir-Hinshelwood route, where both CO and O₂ adsorb on proximate surface sites. Recent efforts have focused on maximising interfacial sites through alloy formation or metal-support interactions, exploiting water- or hydroxyl-assisted activation to stabilise active species and enhance low-temperature performance. Such developments underpin global efforts to deploy hydrogen as a clean energy vector by ensuring reliable and efficient on-board or stationary purification systems.

Research from Nature Portfolio

Recent studies have elucidated how dynamic structural changes in bimetallic catalysts can govern CO oxidation under varying redox conditions. One report demonstrates that PtCu clusters supported on MgO evolve from oxide clusters to alloyed domains with surface CuOx species; at low temperature CuOx drives CO oxidation via a Mars-van Krevelen mechanism, whereas at higher temperature a synergistic PtCu alloy–CuOx interface activates O₂ through a Langmuir-Hinshelwood pathway. In a related advance, fully-exposed Pt–Fe clusters on defective graphene achieve near-complete CO elimination in hydrogen-rich streams at ambient temperature. Atomically dispersed Fe adjacent to Pt maximises oxygen activation on Fe sites and CO adsorption on electron-rich Pt, yielding excellent PROX activity and selectivity while maintaining long-term stability under realistic conditions.

Catalytic Oxidation Processes in Hydrogen-Rich Environments publication trend

The graph below shows the total number of articles in catalytic oxidation processes in hydrogen-rich environments across all publications each year (not limited to Nature Index journals).

Technical terms

Preferential oxidation (PROX): Selective oxidation of CO in the presence of H₂, targeting removal of trace CO while preserving H₂.

Mars-van Krevelen mechanism: Oxidation pathway in which lattice oxygen from the catalyst oxidises the reactant, followed by re-oxidation of the lattice.

Langmuir-Hinshelwood mechanism: Reaction route where both reactants adsorb onto adjacent surface sites before undergoing reaction.

Bimetallic catalyst: Catalyst composed of two different metals, designed to combine distinct catalytic properties and create synergistic active sites.

Strong metal-support interaction (SMSI): Enhanced bonding between metal nanoparticles and oxide supports that can modify electronic properties and stabilise active species.

References

1. Unraveling distinct effects between CuOx and PtCu alloy sites in Pt−Cu bimetallic catalysts for CO oxidation at different temperatures. Nature Communications (2024).
2. Fully-exposed Pt-Fe cluster for efficient preferential oxidation of CO towards hydrogen purification. Nature Communications (2022).
3. Active Pt/CeO2 catalysts prepared by an alcohol-reduction process for low-temperature CO-PROX reaction. Materials for Renewable and Sustainable Energy (2019).
4. Water-assisted generation of catalytic interface: The case of interfacial Pt-FeOx(OH)y sites active in preferential carbon monoxide oxidation. Journal of Catalysis (2024).
5. Highly Effective Pt-Co/ZSM-5 Catalysts with Low Pt Loading for Preferential CO Oxidation in H2-Rich Mixture. Hydrogen (2023).