How to Deal with a Deactivated VOC Catalyst?

Core Reasons for VOC Catalyst Deactivation

The essence of VOC catalyst deactivation is the destruction or functional degradation of active sites, mainly stemming from three factors: First, chemical poisoning, where impurities such as sulfides and halogens in the exhaust gas undergo irreversible reactions with precious metals (Pt, Pd) or non-precious metals (Co, Mn) active components, forming stable compounds that cover the active sites, leading to deactivation within a few hours under low-temperature conditions; Second, physical coverage, where oil mist, dust, and high-boiling-point organic compounds deposit on the catalyst surface, blocking pores and covering active sites, reducing the specific surface area from 200m²/g to below 100m²; Third, high-temperature sintering, where long-term operation at excessively high temperatures (>600℃) leads to agglomeration of active components and sintering of the support, resulting in a significant decrease in catalytic efficiency. In addition, high humidity environments can exacerbate adsorption deactivation of precious metal catalysts, especially platinum-based catalysts, whose activity decreases by 30% at humidity above 70%.

VOC Catalyst Regeneration Methods and Industrial Cases

To address the deactivation problem, mainstream regeneration technologies are divided into two categories: physical and chemical. Physical regeneration includes high-temperature calcination at 600-800℃ (to remove carbon deposits) and ultrasonic cleaning (to remove surface dust); chemical regeneration can dissolve sulfide residues through dilute acid/alkali washing, or restore the valence state of active components through high-temperature reduction with hydrogen gas. Innovative low-temperature plasma regeneration technology can decompose surface deposits at room temperature, reducing energy consumption by 40% compared to high-temperature methods.

Practical case studies demonstrate its effectiveness: A chemical company used a platinum-based catalyst to treat toluene-containing waste gas.  Sulfide poisoning reduced the purification rate from 95% to 62%. After regeneration using a 700°C high-temperature calcination for 2 hours followed by dilute nitric acid washing, the catalyst activity recovered, and the purification rate rose to 92%, saving over 120,000 yuan annually in replacement costs.  It maintained an efficiency of over 85% for four consecutive months. Another example involves a honeycomb cobalt-based catalyst in a paint shop, which became deactivated due to carbon deposition. After ultrasonic cleaning and low-temperature activation at 350°C, the VOC removal rate increased from 65% to 89%, and the anti-carbon deposition ability improved, extending the service life to 1.5 times the original cycle. Laboratory data shows that a titanium-based catalyst still achieved a toluene removal rate of 90% after three plasma regeneration cycles, demonstrating superior stability compared to traditional thermal regeneration.

Precautions after VOC Catalyst Regeneration

Three key aspects require management after regeneration: First, activity testing:  VOC removal rate should be tested using gas chromatography to ensure compliance (≥85%), preventing incomplete regeneration and potential environmental hazards; Second, operating condition adaptation: Control the waste gas temperature between 300-500°C, humidity ≤60%, and pre-treat to remove dust, sulfides, and other impurities to reduce secondary deactivation; Third, storage and inspection: Regenerated catalysts should be sealed and stored in a dry environment, and activity changes should be monitored regularly during operation, with small-scale activation maintenance performed every three months. Furthermore, anti-poisoning catalysts (such as titanium-based and vanadium-based) require targeted pre-treatment processes after regeneration to further extend their service life.

VOC catalyst deactivation can be reversed through precise regeneration technology. Combined with optimized operating conditions and regular maintenance, this can significantly reduce operating and maintenance costs. Choosing the appropriate regeneration process and anti-poisoning catalysts can achieve long-term stable operation of the VOC treatment system, helping companies comply with environmental regulations and improve efficiency while reducing costs.

Author: Hazel
Date: 2025-12-26