In VOCs treatment in the printing and spraying industries, although UV photolysis or low-temperature plasma equipment can efficiently decompose organic waste gas, it inevitably produces a large amount of residual ozone. The role of ozone decomposition catalysts is to rapidly reduce ozone (O₃) to oxygen (O₂). However, many companies report that the catalysts become ineffective within three months of installation, or completely fail under certain weather conditions—the root cause lies in mismatches with operating conditions.

I. Humidity: The Number One Killer of Ozone Decomposition
Printing and spraying exhaust gases typically contain high levels of moisture (especially after the baking process). Water molecules compete with ozone for active sites on the catalyst, causing a sharp decline in ozone decomposition efficiency.

Low Humidity Conditions (RH < 30%): Ordinary manganese-based catalysts are sufficient, offering low cost and high activity.

High Humidity Conditions (RH > 60%): Moisture-resistant ozone decomposition catalysts must be selected, such as hydrophobically modified manganese oxides or supported noble metal (Pt, Pd) catalysts. Noble metal systems are less sensitive to moisture, but their price is 5-8 times that of manganese-based catalysts.

II. Temperature: Low-Temperature Activity Determines Practicality
Printing and spraying exhaust gas temperatures are typically between 25-50℃, falling within the normal temperature range. Conventional manganese-based catalysts exhibit good activity at room temperature, but their efficiency significantly decreases when the exhaust gas temperature drops below 10℃ (in winter or northern regions).

Noble metal ozone decomposition catalysts are virtually unaffected by temperature within the 0-40℃ range, making them suitable for environments with large temperature fluctuations or low temperatures.

III. Space Velocity and Residence Time 

Printing workshops typically experience large volumes of exhaust gas with frequent airflow fluctuations. The catalyst design space velocity (exhaust gas treatment volume per unit time / catalyst volume) should be controlled between 10,000-30,000 h⁻¹. Excessive space velocity will cause ozone to be blown away before it can diffuse to the inner surface of the catalyst. When selecting a catalyst, the actual airflow and catalyst bed pressure drop must be provided to the supplier to ensure a residence time ≥ 0.1 seconds.

IV. Impurities and Poisoning Risk 

Spray painting exhaust gases often contain small amounts of paint mist, silicone oil, and phosphorus- or sulfur-containing substances, which can irreversibly poison the catalyst. For exhaust gases with low purity, precious metal catalysts with stronger resistance to poisoning should be prioritized; if there is a high-efficiency filter upstream, manganese-based catalysts are perfectly adequate.

There is no universal catalyst, only the solution best suited to your production line conditions. We offer free exhaust gas condition diagnostics and small-sample testing of ozone decomposition catalysts to assist you in making accurate selections within 30 days. Feel free to leave a message or send a private message for one-on-one technical consultation.

author:kaka

date:2026/4/3