The principle, necessity and future trend of aircraft cabin ozone purification technology

The hazards of ozone pollution and the necessity of purification
Ozone (O₃), as a strong oxidizing gas, has a high concentration in the stratosphere at the aircraft cruising altitude (8-12 kilometers) and can easily enter the cabin through the air conditioning bleed system. Long-term exposure to high-concentration ozone environment can cause symptoms such as headaches, shortness of breath, eye irritation, and even cardiovascular disease and immune system damage. International aviation regulations clearly stipulate that the ozone concentration in the cabin at a flight altitude of more than 27,000 feet must be less than 100ppb36. In addition, volatile organic compounds (VOCs) generated by aircraft engine exhaust, hydraulic oil leakage, etc. will form secondary pollutants when mixed with ozone, exacerbating cabin odor and health risks16.

Core Principles of Cabin Ozone Purification System
Modern aircraft ozone purification systems use multi-stage collaborative processing technology, combining physical filtration and chemical catalytic decomposition. The specific process is as follows:
Fresh air pretreatment: After introducing external air, particulate matter and microorganisms are removed through a 200-400 mesh stainless steel wire mesh filter to prevent subsequent catalyst clogging.
Catalytic decomposition: The pretreated air enters the radial reactor and is fully contacted with the ozone decomposition catalyst, and ozone is efficiently converted into oxygen. The reactor adopts an integrated design of the central tube and the ozone removal chamber to ensure conversion efficiency at high air velocity (600,000 mL·g⁻¹·h⁻¹).
Temperature regulation and mixing: The purified fresh air is cooled to a suitable temperature by the heat exchanger and mixed with the cabin circulating air to reduce energy consumption and maintain cabin comfort.
Adsorption filtration: The mixed gas passes through an activated carbon or molecular sieve adsorption bed to further remove residual ozone and microorganisms, and the final ozone concentration can be reduced to below 0.1 mg/m³.
Key technologies and performance optimization of ozone decomposition catalysts
Ozone decomposition catalysts are the core of the system and must meet stringent requirements such as low temperature, high efficiency, strong moisture resistance, and long life. Current mainstream technologies include:
1. Metal honeycomb matrix catalysts
Using stainless steel or iron-based alloy honeycomb structures, they are thin and have high open porosity, high mechanical strength and shock resistance, and are suitable for high air velocity environments. The manganese oxide (such as MnO₂) coated on its surface forms a core-shell structure with a cobalt-manganese complex (CoMnOₓ), which improves catalytic activity and stability through synergistic effects.
2. Nitrogen-doped manganese dioxide loaded with precious metals
The manganese dioxide carrier is modified by nitrogen doping to enhance the oxygen vacancy activity, and combined with precious metal (such as Pd, Ag) loading, it can maintain a conversion rate of more than 90% under conditions of -40°C to 25°C and relative humidity of more than 90%.
3. New layered metal hydroxide (LDH) catalysts
Such as nickel-cobalt hydrotalcite structure (Ni-Co LDH), which can decompose ozone in high humidity (RH>90%) and high air velocity (600,000 mL·g⁻¹·h⁻¹) environments, are low-cost and have excellent water resistance, making them suitable for applications in confined cabin spaces.
Optimal working environment and performance requirements
To ensure efficient operation of the purification system, the catalyst needs to adapt to the following complex working conditions:
Temperature range: -40℃ to 50℃, covering ground parking to high-altitude flight environments.
Humidity tolerance: It needs to maintain activity at a relative humidity of more than 90% to prevent water molecules from occupying the active sites of the catalyst.
Long-term stability: The service life needs to be more than 3 years, and the core-shell structure design can delay the loss of active components and reduce maintenance costs.
The comprehensive value of ozone purification technology
Health protection: Reduce the risk of respiratory diseases, especially protect sensitive groups such as children and pregnant women.
Compliance guarantee: Meet the ozone concentration limit requirements of the International Aviation Organization (FAA, ICAO) to avoid flight delays or diversions.
Energy saving and environmental protection: Catalytic decomposition does not require additional energy consumption, which is in line with the "dual carbon" goals of the aviation industry.
Future development trends
With the advancement of material science, ozone purification technology is developing towards lightweight and intelligent. For example:
Composite coating technology: Improve the moisture resistance of the catalyst through carbon coating or hydrophobic layer design.
Modular integrated system: Integrate the catalytic reactor, heat exchanger and adsorption purification unit to reduce the volume and optimize the airflow distribution.
Intelligent monitoring and regeneration: Combine sensors to monitor ozone concentration in real time, and use the back-purge system to extend the life of the catalyst