Do Ozone Decomposition Catalysts Require Regeneration for Long-Term Use in General Exhaust Gas Purification?

Ozone decomposition catalysts, a material commonly used in industrial waste gas treatment and environmental purification, are being explored for their potential use in the more general field of automotive exhaust gas treatment.

I. Core Conditions Required for General Exhaust Gas Purification

Converting automotive exhaust gases into harmless substances is not a single reaction, but a systemic process that requires simultaneously meeting multiple stringent conditions.
High-temperature environment: Mainstream three-way catalytic converters require high temperatures (usually 250-850°C) to start and operate efficiently, which depends on the heat of the engine exhaust.
Simultaneous treatment of multiple pollutants: It must be able to simultaneously treat three main pollutants:
Carbon monoxide (CO): Oxidized to carbon dioxide (CO₂).
Hydrocarbons (HC): Oxidized to water and carbon dioxide.
Nitrogen oxides (NOx): Reduced to nitrogen (N₂) and oxygen (O₂).
Precise air-fuel ratio: Three-way catalytic converters require the engine to operate within a very narrow window near the stoichiometric air-fuel ratio (approximately 14.7:1) to ensure that oxidation and reduction reactions proceed efficiently and simultaneously.
Low airflow resistance and high durability: The catalyst carrier (such as honeycomb ceramic) must have extremely low back pressure so as not to affect engine performance, and at the same time be able to withstand the high temperatures, vibrations, and potential toxins (such as sulfur and lead) in the exhaust gas.

II. Are Ozone Decomposition Catalysts Suitable for General Exhaust Gas Purification? 

The answer is no, ozone decomposition catalysts are not directly applicable to treating typical automobile exhaust.

The reason is that the "target" is completely different:
The core function of an ozone decomposition catalyst is to efficiently decompose ozone (O₃) into oxygen (O₂) at room temperature or low temperatures. Its design goal is to treat a single, highly oxidizing O₃ molecule.
Ordinary automobile exhaust is a complex mixture, primarily composed of CO, HC, and NOx, and the treatment process requires simultaneous oxidation and reduction reactions, and relies on high temperatures.
However, in specific industrial exhaust gas treatment scenarios, if the exhaust gas contains ozone or requires advanced oxidation processes utilizing ozone to treat VOCs (volatile organic compounds), then ozone decomposition catalysts become crucial for treating residual ozone in the exhaust gas at the end of the process, preventing secondary ozone pollution.

III. Application Principles and Case Studies of Ozone Decomposition Catalysts

Application Principles:
Ozone decomposition catalysts typically use transition metal oxides (such as oxides of manganese, copper, and cobalt) or supported noble metals as active components. Their mechanism is to catalyze the decomposition reaction of ozone: O₃ → O₂ + O• (active oxygen). The catalyst surface provides active sites, significantly lowering the activation energy of this reaction, allowing ozone to decompose quickly and completely at room temperature, preventing its escape.
Practical Application Cases:
In the ozone disinfection process of large water treatment plants, the effluent or exhaust gas may contain ozone that has not been completely dissolved or reacted. If these ozone-containing exhaust gases are directly discharged, they will cause harm to the surrounding environment and human health. In this case, the factory will install an exhaust gas destruction device filled with a honeycomb-shaped ozone decomposition catalyst in the exhaust pipe. The ozone-containing gas flows through the catalyst bed, where the O₃ is catalytically decomposed into harmless O₂ at room temperature, ensuring that the final emissions meet the standards. This is a mature and essential application.

IV. Long-Term Use and Regeneration: Specific Practical Methods

Even in the field of ozone exhaust gas treatment where it is applicable, the catalyst faces temporary deactivation due to water vapor condensation, dust coverage, and trace organic matter contamination. For long-term use, maintenance and regeneration are crucial. 

1. Preventive Maintenance (Extending Lifespan):

Pre-treatment: Install oil removal, dust removal, and water removal (such as condensers and dryers) devices before the catalyst bed to reduce physical coverage and poisoning of the catalyst surface by upstream impurities.
Control operating conditions: Avoid prolonged operation at exhaust gas temperatures below the dew point, which can lead to water condensation inside the catalyst. Appropriately increasing the inlet temperature (e.g., 50-80°C) can significantly improve moisture resistance and service life.
Regular monitoring: Install an ozone concentration monitor to monitor the outlet concentration in real time. A sustained increase in outlet concentration indicates a possible decrease in catalyst activity, requiring inspection.
2. In-situ Regeneration Methods (Restoring Activity):
Hot air purging: For deactivation mainly caused by water vapor or volatile organic compound adsorption, clean hot air (100-120°C) can be continuously passed through the catalyst bed for several hours during system shutdown to evaporate water and desorb some pollutants, restoring most of the activity.
Low-temperature drying pre-treatment: For small or removable catalyst modules, they can be placed in an oven and dried at 100-120°C for 8-12 hours. This is the most direct and effective method for dealing with humidity effects.
3. Professional Regeneration and Replacement:
Chemical cleaning: For catalysts contaminated with stubborn organic matter or sulfides, professional manufacturers need to use specific chemical solutions for cleaning and regeneration. This operation should not be performed by the user.
Partial replacement: For large packed bed reactors, a "layered replacement" strategy can be adopted. The most heavily contaminated part of the catalyst upstream is replaced first, while the downstream part with acceptable activity continues to be used to reduce costs.
Complete replacement: When the catalyst reaches its chemical lifespan (sintering, loss of active components, or irreversible chemical poisoning), and regeneration is ineffective, a complete replacement is necessary. Choosing a reliable brand product with supporting durability data is crucial.

Ozone decomposition catalysts are not designed for treating complex components of ordinary automobile exhaust, but their main application is in the purification of industrial ozone exhaust. Within its applicable field, although catalysts will gradually deactivate, a comprehensive strategy of "prevention first, monitoring and early warning, and timely regeneration" can ensure long-term, stable, and economical operation. Among these, controlling the quality of the incoming gas, avoiding water vapor condensation, and periodic hot air regeneration are the most practical and effective methods that users can implement on-site to guarantee long-term use.

author: Hazel
date: 2026-01-15