Ozone Decomposition Catalyst in UV Ozone Disinfection Applications

UV ozone disinfection technology utilizes 254 nm UV light to irradiate ambient air, converting oxygen (O₂) into ozone (O₃). Ozone is a powerful oxidant that can disrupt the DNA or RNA of viruses and bacteria, achieving high‑efficiency sterilization. This technology combines the immediate germicidal effect of UV light with the broad‑spectrum, long‑lasting oxidizing power of ozone, and is widely used in space disinfection, water treatment, medical instrument sterilization, food processing, and many other fields.

However, ozone itself is a strong oxidizing gas that can irritate and damage the human respiratory tract. If the residual ozone left after the disinfection process is discharged directly without treatment, it will not only pollute indoor air but also pose health risks to operators and nearby personnel. Therefore, how to efficiently and safely remove residual ozone after UV ozone disinfection has become a critical issue that must be addressed in the application of this technology.

1. Risks of Ozone Residuals and the Need for Treatment

During the operation of UV ozone disinfection equipment, the amount of ozone generated depends on factors such as the power of the UV lamp, exposure time, and air flow rate. After disinfection, unused ozone remains in the enclosed space or inside the equipment, and its concentration can reach tens to hundreds of ppm. According to occupational safety and health standards, the permissible exposure limit for ozone in workplace air is typically 0.1 ppm (8‑hour time‑weighted average). Above this level, personnel may experience coughing, chest tightness, headaches, and long‑term exposure may even cause irreversible lung damage.

Studies have quantitatively examined UV‑induced ozone decomposition: when the initial ozone concentration ranged from 69.7 to 365 ppm, passing through a UV irradiation zone with a total length of 103 cm achieved only about 75% decomposition. This indicates that relying solely on UV light itself leaves a considerable proportion of residual ozone untreated, necessitating additional off‑gas treatment measures.

Common methods for treating residual ozone include activated carbon adsorption, thermal decomposition, and catalytic decomposition. Although activated carbon is simple, it reacts with ozone to form carbon dioxide, leading to high consumption and a risk of combustion. Thermal decomposition requires heating to 300–400 °C, which consumes significant energy. In comparison, catalytic decomposition operates efficiently at ambient temperature, requires no external energy input, and produces no secondary pollution, making it the preferred solution for ozone off‑gas treatment in the UV ozone disinfection industry.

2. Technical Principle and Key Advantages of Catalytic Decomposition

Ozone decomposition catalysts typically use transition metal oxides (such as oxides of manganese, copper, cobalt, cerium, etc.) as active components. The working principle is based on redox reactions on the catalyst surface: ozone molecules (O₃) adsorb onto active sites on the catalyst surface and, through a series of electron transfer steps, decompose into oxygen molecules (O₂). The overall reaction can be expressed as: 2O₃ → 3O₂. The catalyst is not consumed in the reaction; it merely provides a platform for the reaction to occur, enabling long‑term use.

Compared with other ozone decomposition methods, catalytic decomposition offers the following significant advantages in UV ozone disinfection scenarios:

• Ambient‑temperature operation, no external energy required. High‑quality manganese‑based catalysts can efficiently decompose ozone at room temperature. This is especially important for UV ozone disinfection equipment—since the disinfection process itself occurs at ambient temperature, off‑gas treatment requires no additional heating or lighting, resulting in virtually zero operating cost.
• High decomposition efficiency. In a properly designed catalytic reactor, ozone decomposition efficiency can exceed 99%. For example, honeycomb‑type catalysts can achieve >99% removal, reducing high‑concentration ozone off‑gas to safe emission levels.
• Safe, non‑toxic, and no secondary pollution. The only product of catalytic decomposition is oxygen; no harmful byproducts are generated. The catalyst contains no combustible materials such as activated carbon, so there is no risk of combustion when treating high‑concentration ozone.
• Long service life. High‑quality catalysts can have a service life of more than 2 years.

3. Key Performance Indicators for Catalysts

When selecting a catalyst for UV ozone disinfection equipment, the following performance indicators deserve special attention.

Specific Surface Area

A higher specific surface area provides more active sites per unit volume, enhancing the catalyst's capacity. High‑quality ozone decomposition catalysts have a specific surface area of 160–240 m²/g, with abundant micropores inside the catalyst that effectively adsorb ozone molecules and promote catalytic decomposition.

Active Component Content

The effective content of active components directly determines catalytic efficiency. Catalysts manufactured by chemical synthesis allow precise control over each process parameter, and the active component content can reach over 80%; powder forms without binders can even achieve more than 99% active content.

Structural Form and Pressure Drop

UV ozone disinfection equipment typically handles large air flows with low ozone concentrations. Honeycomb‑type catalysts offer advantages such as easy loading/unloading and low flow resistance, effectively reducing fan energy consumption in high‑flow scenarios.

Mechanical Strength

Catalysts must withstand airflow impact and temperature variations during long‑term operation, so mechanical strength directly affects service life. High‑quality catalysts have an average crush strength greater than 40 N/cm, and some products can even reach 45 N/cm or more.

Bulk Density

Bulk density directly influences the catalyst loading volume and equipment cost. High‑specific‑surface‑area catalysts can have a bulk density as low as 0.68–0.70 g/cm³, reducing the weight of catalyst required to treat the same air flow by about one‑third.

4. Typical Application Scenarios and Technical Considerations

Ozone Sterilization Cabinets and Disinfection Rooms

After sterilizing utensils, medical instruments, or surfaces in an ozone sterilization cabinet, residual ozone inside the cabinet must be rapidly decomposed before the door can be safely opened. The catalyst is typically installed in the exhaust duct or internal circulation system of the cabinet, and the catalytic decomposition process is automatically initiated after the disinfection cycle ends.

Space Disinfection Equipment (Human‑Occupancy Scenarios)

In disinfection scenarios where personnel may be present during operation, real‑time ozone control is especially critical. Studies have developed high‑efficiency disinfectors based on vacuum ultraviolet radiation combined with manganese‑based catalytic ozone decomposition technology. These devices use 254 nm UV light and highly oxidizing ozone to sterilize the space, while an additional manganese‑based catalytic decomposition module removes excess ozone, enabling simultaneous human occupancy. This design has important value in medical facilities, public spaces, and similar environments.

Ozone Off‑Gas Treatment in Swimming Pool Water Treatment Systems

A swimming pool ozone‑UV advanced oxidation disinfection system consists of an air compressor, oxygen generator, ozone generator, UV lamps, UV reactor, off‑gas treatment unit, and intelligent control module. The ozone generator produces ozone via corona discharge, and the pool water mixed with ozone enters the UV reactor, where photocatalytic reactions generate highly oxidative hydroxyl radicals that decompose organic matter and inactivate microorganisms. In such systems, the off‑gas treatment unit is crucial for decomposing residual ozone.

Museums, Libraries, and Other Sensitive Environments

Ozone can oxidize and damage paper, textiles, cultural relics, and other materials. In museums, libraries, and similar venues that use UV ozone disinfection, residual ozone must be thoroughly removed after disinfection to protect valuable collections and artifacts. Catalytic decomposition, which produces only oxygen and has no corrosive effects, is ideal for these settings.

5. Practical Engineering Considerations

When integrating a catalytic decomposition unit into UV ozone disinfection equipment, particular attention should be paid to the following aspects.

Matching Operating Conditions

Catalyst selection should be based on actual operating parameters—including inlet ozone concentration, gas flow rate, temperature, humidity, and the possible presence of other impurity gases. Ozone concentrations vary widely across different scenarios, from a few ppm to several hundred ppm, so the appropriate catalyst specification must be chosen. The maximum treatment concentration of the catalyst can reach 90 mg/L, and the selection should ensure that the actual concentration falls within this range.

Installation Position and Airflow Distribution

The catalyst should be placed in the airflow path to ensure that all ozone‑containing gas passes through the catalytic bed. At the same time, direct contact of the catalyst with liquid water or excessively humid gas should be avoided, as this can impair catalytic efficiency.

Regular Maintenance and Performance Monitoring

Although the catalyst has a service life of more than 2 years, the catalyst bed should be regularly inspected for clogging and activity decay. It is recommended to reserve sampling ports or monitoring interfaces in the system design to facilitate routine maintenance.

Cost Evaluation

Cost evaluation of catalysts should not focus solely on unit price; comprehensive costs must be calculated by considering important factors such as bulk density, catalytic efficiency, and service life. Although a longer‑lasting catalyst may have a higher initial purchase cost, it may be more economical over the entire life cycle.

UV ozone disinfection technology plays an irreplaceable role in many industries due to its high efficiency and broad‑spectrum germicidal capability. Catalytic decomposition, with its unique advantages of ambient‑temperature operation, high efficiency, and no secondary pollution, provides a reliable engineering solution for removing residual ozone after disinfection. As awareness of indoor air quality and occupational health and safety continues to grow, the application of ozone decomposition catalysts in the UV ozone disinfection industry will become increasingly widespread and in‑depth. For engineers and technical professionals involved in the design and operation of UV ozone disinfection equipment, a thorough understanding of the technical principles and key performance indicators of catalytic decomposition will facilitate the construction of safer, more efficient, and more economical ozone off‑gas treatment systems.