SAPO-34 Properties

SAPO-34 catalyst is a silicoaluminophosphate with CHA topology. Three properties define its role as the dominant MTO catalyst for supplier evaluation: cage-based shape selectivity, mild acidity that suppresses hydrogen transfer, and full regenerability.

Mild Acidity

As a silicoaluminophosphate, SAPO-34 has inherently milder acidity than aluminosilicate zeolites. Si substitutes for P in the AlPO4-34 framework, creating isolated acid sites. This mild acidity favours the olefin-producing methylation and cracking pathways in MTO while suppressing hydrogen transfer that would convert olefins to paraffins and aromatics.

Cage-Based Shape Selectivity

8-MR windows (3.8 A) control access to chabazite cages. Methanol enters and reacts to form olefins; only C2 and C3 olefins can exit. Larger molecules remain trapped and undergo further reaction. This confinement produces 80 to 90 percent C2 plus C3 selectivity — unmatched by any aluminosilicate.

Regenerability

Coke accumulates in chabazite cages but burns cleanly at 500 to 550 C. After 50 plus reaction-regeneration cycles, SAPO-34 retains above 90 percent of initial activity. Steam exposure during regeneration should be minimised to prevent framework dealumination.

See SAPO-34 Structure and the product hub.