Catalytic Soot Oxidation Mechanisms and Materials

Catalytic soot oxidation is a cornerstone of modern emissions control, converting harmful carbonaceous particulates into carbon dioxide at reduced temperatures. Reaction pathways generally follow Langmuir–Hinshelwood, Eley–Rideal or Mars–van Krevelen mechanisms, in which soot carbon reacts with adsorbed oxygen species or lattice oxygen. Key to activity is the generation and mobility of reactive oxygen, often governed by oxygen vacancies in metal oxides. Noble metals such as platinum or palladium deliver high activity but are costly and prone to sintering. This has prompted extensive research into alternative materials including transition metal oxides, perovskites, spinels and single‐atom catalysts. Structural design—ranging from three‐dimensionally ordered macroporous architectures to nanostructured doped lattices—aims to maximise soot–catalyst contact, enhance oxygen mobility and preserve active sites under hydrothermal ageing. The interplay with NOx and secondary oxidants such as N₂O can further lower ignition temperatures. Such advances underpin the next generation of diesel particulate filters and industrial reactors, supporting tighter emission standards and improved air quality worldwide.

Research from Nature Portfolio

Recent studies have demonstrated the potential of single‐atom catalysts for soot oxidation. Atomically dispersed ruthenium on ceria surfaces exhibits exceptionally high turnover frequencies, rivalling platinum‐based systems, by promoting interfacial charge transfer that lowers the activation barrier for NO and O₂ activation. This approach achieves robust performance and thermal stability under cyclic redox conditions. In parallel, hierarchically porous potassium–manganese oxide catalysts supported on silica have been engineered with three‐dimensionally ordered macroporous frameworks. These structures combine macropores for soot ingress with microporous tunnels for gas adsorption, leveraging synergistic K–Mn interactions to activate O₂ and NOx at markedly lower temperatures than conventional catalysts.

Catalytic Soot Oxidation Mechanisms and Materials publication trend

The graph below shows the total number of articles in catalytic soot oxidation mechanisms and materials across all publications each year (not limited to Nature Index journals).

Technical terms

Langmuir–Hinshelwood mechanism: reaction between two surface-adsorbed species leading to oxidation.

Eley–Rideal mechanism: direct reaction of a gas-phase molecule with an adsorbed species on the catalyst surface.

Mars–van Krevelen mechanism: oxidation via lattice oxygen with subsequent re-oxidation of the catalyst by gas-phase oxygen.

Oxygen vacancy: a defect site in a metal oxide lattice where an oxygen atom is missing, enhancing oxygen mobility and reactivity.

Single‐atom catalyst: catalyst comprising isolated metal atoms dispersed on a support to maximise atom efficiency and unique electronic properties.

Three-dimensionally ordered macroporous (3DOM) structure: a scaffold featuring interconnected macropores arranged in a regular pattern, improving reactant accessibility.

Diesel particulate filter (DPF): a device that traps and catalytically oxidises soot particles from diesel exhaust to reduce particulate emissions.

References

1. Novel and active Bi2Zr1.9M0.1O7 (M = Mn, Fe, Co, Ni) catalysts for soot particle removal: Engineering surface with rich oxygen defects via partial substitution of Zr‐site. EcoEnergy (2024).
2. A single site ruthenium catalyst for robust soot oxidation without platinum or palladium. Nature Communications (2023).
3. Catalytic Soot CombustionGeneral Concepts and Alkali Promotion. ACS Catalysis (2023).
4. A review on the catalytic combustion of soot in Diesel particulate filters for automotive applications: From powder catalysts to structured reactors. Applied Catalysis A General (2016).
5. Ordered micro/macro porous K-OMS-2/SiO2 nanocatalysts: Facile synthesis, low cost and high catalytic activity for diesel soot combustion. Scientific Reports (2017).
6. Simultaneous removal of NOx and soot particulate from diesel exhaust by in-situ catalytic generation and utilisation of N2O. Applied Catalysis B Environment and Energy (2018).