How to Determine if a Catalyst Has Become Inactive?

I. Core Reasons for Catalyst Deactivation

Catalyst deactivation is not a sudden event, but rather the result of long-term interaction between operating conditions and materials. Four core reasons account for over 95% of deactivation:

Surface fouling and blockage (62%): Oil stains in corona discharge workshops, ink residue in printing workshops, and PM2.5 in automotive exhaust can adhere to the pores. Data from a printing company shows that without pretreatment, the catalyst's pores were 40% blocked due to fouling within 3 months.

Active component poisoning (21%): Sulfur-containing fuel exhaust and chlorine-containing ink solvents react with platinum-based active components. A car repair shop experienced a 70% irreversible drop in catalyst activity within 2 months due to the use of low-quality fuel.

High-temperature sintering (12%): When the air outlet temperature of the corona discharge machine exceeds 80°C, the active components will agglomerate. In an electronics factory, the catalyst's active sites decreased by 35% within 6 months because the catalytic device was located near high-temperature equipment.

Natural aging (5%): Under normal operating conditions, active components are lost year by year. High-quality catalysts have a lifespan of 3-5 years, while inferior products only last 1-2 years. 

II. Direct Impacts of Catalyst Deactivation

Deactivation not only affects environmental compliance but also increases operating costs:

Environmental risks: After catalyst deactivation in a corona discharge workshop, the ozone emission concentration increased from 0.03 mg/m³ to 0.21 mg/m³, far exceeding the national standard of 0.1 mg/m³, resulting in a fine of 50,000 RMB per incident.

Production losses: Deactivation in a printing workshop led to residual odors, a 12% decrease in product qualification rate, and a 20% increase in rework costs.

Health hazards: Due to catalyst deactivation in a workshop, the absenteeism rate due to ozone poisoning among employees increased by 15%.

III. Four Steps to Accurately Determine Catalyst Deactivation

Sensory Initial Assessment
If a pungent ozone odor reappears after the corona discharge workshop starts operation, or if the odor in the printing workshop persists for more than one hour, or if the catalyst surface becomes black and sticky, deactivation can be initially determined. An employee at an electronics factory detected the deactivation problem three weeks in advance through "smelling and observing the appearance."

Simple Test
Back-flush with 0.3-0.5 MPa compressed air. If there is a lot of dust and oil at the outlet, it indicates scaling. If the catalyst temperature rise during operation is less than 5℃ (normal is 5-10℃), then the activity has decreased.

Instrumental Detection
Key indicator: the difference in ozone concentration between the inlet and outlet. The treatment efficiency of a new catalyst is ≥95%. If it drops below 70% (e.g., inlet 1.0 mg/m³, outlet 0.3 mg/m³), or the outlet concentration > 0.1 mg/m³, it indicates deactivation. In automotive exhaust treatment, exceeding the national standard of 0.05 mg/m³ for nitrogen oxides also requires attention.

Historical Data Comparison

If the replacement cycle is shortened from one year to six months, or if energy consumption increases by 15% under the same working conditions, maintenance is required even if the standards are not exceeded. 

IV. Scientific Treatment Solutions for Catalyst Deactivation

Mild fouling: Compressed air purging + drying at 80°C, cost only 5 RMB/m²; Moderate deactivation: Original manufacturer regeneration (re-coating with active components), cost is 50% of replacement, performance restored to over 90%; Severe deactivation (treatment efficiency <60%): Replace with a specialized catalyst, such as an anti-ink fouling type for printing workshops or an anti-sulfur type for automotive exhaust, extending the lifespan by 30%.

Regular assessment and maintenance are key to efficient catalyst operation. Monthly visual inspection, quarterly simple testing, and semi-annual instrument testing are recommended. Using high-quality catalysts can reduce the risk of deactivation by 40%.

Author: Hazel
Date: 2025-12-18