SSZ-13 Properties

SSZ-13 zeolite catalyst combines the CHA framework with aluminosilicate chemistry, creating properties uniquely suited to SCR: high ion-exchange capacity for Cu and Fe, exceptional hydrothermal stability, and cage-confined active sites for supplier-grade NOx reduction.

Ion-Exchange Capacity

Framework Al creates negative charges balanced by Cu2+ or Fe3+ through aqueous ion exchange. Si/Al ratios of 12 to 18 provide enough Al for 2 to 4 wt percent metal loading while retaining hydrothermal stability. This is fundamentally different from SAPO-34, which has very limited ion-exchange capacity.

Hydrothermal Stability

Cu-SSZ-13 retains CHA crystallinity to 850 C dry and 750 C in 10 percent steam. The structural basis: chabazite cages confine Cu ions at specific sites, preventing migration and CuO clustering during DPF regeneration. This is the property that made Cu-SSZ-13 the diesel SCR standard.

SCR Activity

Cu-SSZ-13 delivers above 90 percent NOx conversion at 200 C fresh, retaining above 80 percent after 800 C hydrothermal aging for 16 hours. Operating window of 150 to 550 C at above 80 percent conversion. N2 selectivity above 95 percent.

See SSZ-13 Structure and the product hub.