Views: 0 Author: QT Publish Time: 2025-08-08 Origin: QT
In industrial SCR (Selective Catalytic Reduction) systems—whether on a diesel engine, a refinery flue, or a coal-fired power plant—catalyst deactivation is one of the most expensive and frustrating problems.
You think you’ve bought a high-quality catalyst, yet performance drops in months. NOx emissions creep up. Maintenance shuts down the line. Costs snowball.
The good news? These failures almost always follow predictable patterns, and in many cases, a better choice of catalyst material can extend service life by years.
From field surveys and industry reports, the most common causes of SCR catalyst problems are:
1.Hydrothermal Aging
Exposure to 700–850 °C exhaust gas with high water vapor destroys the zeolite framework, reducing active sites.
2.Sulfur Poisoning
SO₂ in the flue gas converts to sulfates, blocking active copper or iron sites.
3.Ammonia Slip & Side Reactions
Poor NH₃ storage and uneven distribution lead to unreacted ammonia emissions or the formation of N₂O (a greenhouse gas).
4.Raw Material Impurities
Even a few ppm of heavy metals in feed gas can cause irreversible poisoning.
Most conventional medium-pore zeolites (like ZSM-5) are vulnerable to hydrothermal collapse above 700 °C, especially in wet conditions.
Kamasamudram et al. (Applied Catalysis B: Environmental, 2013) found that ZSM-5 catalysts lost more than 40% of NOx conversion after 24 hours at 800 °C in 10% steam—while small-pore CHA-framework zeolites retained the majority of their activity.
This is where SSZ-13 comes in. It’s a small-pore zeolite (CHA structure) with 3.8 Å pores, which inherently resists both steam-induced dealumination and SO₂ attack.
Advantages of SSZ-13 for High-Temperature SCR:
1.Exceptional Hydrothermal Stability
Zhang et al. (Catalysis Science & Technology, 2021) reported that Cu-SSZ-13 maintained >90% NOx conversion after aging at 850 °C for 50 hours in 10% steam.
2.Better SO₂ Tolerance
Chen et al. (Frontiers in Chemistry, 2022) found that moderate SO₂ exposure at high temperatures had minimal impact on Cu-SSZ-13 activity, due to strong Cu²⁺ anchoring.
3.Reduced Ammonia Slip
Small-pore channels improve NH₃ adsorption at reaction temperature, lowering unreacted ammonia in the exhaust.
4.Uniform Active Sites
Even distribution of Z₂Cu species provides stable performance across different load conditions.
If you are planning to upgrade or replace SCR catalysts, here’s what you should request from suppliers:
Full Structural Analysis – XRD pattern showing CHA peaks
BET Surface Area Report – >400 m²/g indicates intact structure
Si/Al Ratio Documentation – typically 10–30 for optimal balance
SO₂ Resistance Data – preferably from 3rd-party labs
NH₃-TPD Profile – confirms storage capacity and site strength
Pro tip: If your plant operates above 750 °C or processes sulfur-rich fuel, SSZ-13 should be your first candidate.
Q1: Can SSZ-13 completely prevent sulfur poisoning?
A: No catalyst is 100% immune, but SSZ-13 shows slower sulfate formation and better recovery after regeneration than ZSM-5 or Fe-zeolites.
Q2: Will SSZ-13 work in both stationary and mobile SCR systems?
A: Yes, it’s used in diesel trucks, marine engines, power plants, and refinery stacks.
Q3: What if my system runs below 400 °C most of the time?
A: Low-temperature performance depends on the metal loading and dispersion. Cu-SSZ-13 generally performs better in the 200–500 °C range than many other zeolites.
Q4: How do I verify genuine SSZ-13?
A: Ask for XRD, BET, Si/Al ratio, and Cu site characterization reports. We also recommend visiting the production site if possible.
Academic References
Kamasamudram, K. et al. (2013). Applied Catalysis B: Environmental, "Mechanisms of Deactivation for Cu-SSZ-13 and Other Zeolites."
Zhang, X. et al. (2021). Catalysis Science & Technology, "Hydrothermal Stability of Cu-SSZ-13 for NOx Removal."
Chen, H. et al. (2022). Frontiers in Chemistry, "SO₂ Resistance of Cu-SSZ-13 Under SCR Conditions."
