SSZ-13 Zeolite Catalyst

SSZ-13 is a high-silica CHA aluminosilicate zeolite used as a precursor for selective catalytic reduction (SCR), and in MTO, methane-to-olefins, and denitrification research. Its 8-membered ring windows (~3.8 A) and chabazite cages provide sites for ion exchange. ZeoCatalyst’s current handbook lists Na-form, NH4-form, and H-form SSZ-13 base powder; finished Cu- or Fe-exchanged catalyst supply requires separate technical confirmation.

Cu-SSZ-13 is the industry-leading formulation: it combines exceptional low-temperature SCR activity with hydrothermal stability that survives repeated exposure to 800 °C+ during diesel particulate filter (DPF) regeneration — a requirement that eliminated earlier-generation SCR catalysts. Fe-SSZ-13 offers an alternative for high-temperature and sulfur-containing exhaust streams where iron’s resistance to SO₂ poisoning outweighs copper’s superior low-temperature activity.

If your application is mobile diesel SCR (on-road, non-road, marine), Cu-SSZ-13 is the default choice. If your application is stationary NOx abatement with sulfur present in the fuel or exhaust, Fe-SSZ-13 or Beta zeolite may be more cost-effective.

How to Select the Right SSZ-13 Zeolite Catalyst Grade

SSZ-13 grade selection starts with four base-powder parameters: SiO2/Al2O3 ratio, cation form, primary crystal size, and powder D50. Metal loading and SCR performance apply only to a separately specified metal-exchanged catalyst.

SiO2/Al2O3 ratio (SAR) controls ion-exchange capacity, acidity, and stability. The current supply range is 10-80, with standard catalogue bands at 12-14, 16-18, 20-22, 28-30, and 30-80. Select a band against the intended exchange level and durability protocol.

Metal choice (Cu vs Fe) determines the operating temperature window. Copper-exchanged SSZ-13 delivers superior NOx conversion at 150-350 °C, the temperature range of light-duty and most heavy-duty diesel exhaust. Iron-exchanged SSZ-13 peaks at 350-550 °C and tolerates higher SO₂ concentrations, making it suitable for stationary engines, marine diesels burning high-sulfur fuel, and power plant SCR.

Metal loading typically ranges from 2-4 wt% for Cu and 1-3 wt% for Fe. Under-loading leaves active sites unused; over-loading leads to metal oxide clustering (CuO or Fe₂O₃) that reduces activity and can catalyze unwanted ammonia oxidation at high temperatures. The optimum is determined by the Si/Al ratio — higher Al content supports higher metal loading before clustering begins.

Precursor form depends on your manufacturing process. Na-, H-, and NH₄-SSZ-13 are the current handbook forms. A pre-exchanged Cu- or Fe-SSZ-13 request must be qualified separately for metal loading, dispersion, particle distribution, activity, and aging resistance.

Current SSZ-13 Supply Range

Metal-exchanged, washcoat-ready, or shaped products are reviewed as separate specifications before quotation.

The batch COA records the acceptance parameters agreed for the selected base powder. Primary crystal size and powder D50 are different measurements; specify which one is critical. A metal-exchanged catalyst COA requires a separate agreed list that may include metal loading by ICP-OES and application-specific tests.

SCR Performance: What Cu-SSZ-13 Delivers

Cu-SSZ-13 replaced Cu-ZSM-5 and Cu-Beta as the diesel SCR standard for a specific reason: hydrothermal stability. Earlier Cu-zeolite SCR catalysts lost significant activity after repeated exposure to temperatures above 650 °C during DPF regeneration. Cu-SSZ-13 retains >80% of its initial NOx conversion activity after hydrothermal aging at 800 °C for 16 hours — a standardized severe aging protocol that simulates full useful life.

The following values describe application benchmarks for Cu-SSZ-13 chemistry, not guaranteed ZeoCatalyst supply specifications. They require validation against a named catalyst grade, test protocol, and aging method:

• NOx conversion at 200 °C: >90% (fresh), >80% (after 800 °C/16h hydrothermal aging)
• Operating window: 150-550 °C with >80% conversion
• N₂ selectivity: >95% across the operating window (minimizes N₂O greenhouse gas byproduct)
• Ammonia storage capacity: 0.8-1.2 mmol NH₃/g at 200 °C (supports high transient conversion)
• Hydrothermal stability limit: Retains CHA crystallinity to 850 °C (dry), 750 °C (10% steam)

Fe-SSZ-13 sacrifices some low-temperature activity for sulfur tolerance. In exhaust streams with 50-200 ppm SO₂, Fe-SSZ-13 retains >85% of its initial activity after 500 hours of exposure, where Cu-SSZ-13 may decline by 15-30% depending on temperature and SO₂ concentration.

See SSZ-13 for SCR for detailed operating conditions by application.

MTO and Other Applications

SSZ-13 can catalyze methanol-to-olefins (MTO) — it shares the same CHA topology as SAPO-34, the dominant MTO catalyst. However, SSZ-13’s stronger acidity produces lower total light olefin selectivity (60-75% vs SAPO-34’s 80-90%) and higher C₄+ byproducts. It is occasionally used in research or niche MTO applications where the higher propylene-to-ethylene ratio of aluminosilicate CHA is desired, but it does not compete with SAPO-34 as a commercial MTO catalyst.

SSZ-13 membranes and adsorbents are used in gas separation, particularly CO₂/CH₄ separation, where the 8-MR windows provide kinetic selectivity favoring CO₂ over methane.

Technical Documentation

• SSZ-13 Technical Data Sheet — Current base-powder SiO₂/Al₂O₃, BET, crystal-size, ion-form, and COA guidance
• SSZ-13 for SCR — Application-specific grade selection and operating conditions
• Best Zeolite for SCR — Cu-SSZ-13 vs Fe-SSZ-13 vs Beta comparison
• SAPO-34 vs SSZ-13 — CHA framework comparison: chemistry determines application

When requesting a sample, specify the application, required SiO2/Al2O3 band, Na/NH4/H form, crystal or powder particle-size requirement, and quantity. For SCR work, state whether you need base powder or a separately qualified metal-exchanged catalyst.