ZSM-35 zeolite, possessing the FER (Ferrierite) framework topology, is a medium-pore aluminosilicate zeolite distinguished by its unique two-dimensional channel system comprising intersecting 10-membered ring (10-MR) channels (5.4 × 4.2 Å) and 8-membered ring (8-MR) channels (3.5 × 4.8 Å). First synthesized by Beech at Imperial Chemical Industries (ICI) in 1981, ZSM-35 has emerged as one of the most versatile and industrially relevant zeolites, particularly in methanol-to-olefins (MTO), shape-selective isomerization, alkylation, and adsorptive separation processes. This article presents a comprehensive overview of the catalytic, separation, and emerging applications of ZSM-35 zeolite, discussing its structural advantages, performance benchmarks, and future research directions.
Keywords: ZSM-35 zeolite, Ferrierite framework, MTO reaction, shape-selective catalysis, xylene isomerization, ethylene selectivity
Zeolites have revolutionized the petrochemical and chemical industries over the past six decades, serving as the backbone of numerous catalytic and separation processes. Among the more than 250 known zeolite framework types, ZSM-35 occupies a special niche owing to its hybrid pore architecture that combines medium-pore (10-MR) and small-pore (8-MR) characteristics within a single crystal.
ZSM-35 was first reported by Beech (1981) at ICI and was assigned the FER code by the International Zeolite Association (IZA). The name "ZSM-35" derives from the Zeolite Socony Mobil nomenclature, where the number 35 indicates its order of discovery within the ZSM series.
The chemical composition of ZSM-35 can be generally expressed as:
The Si/Al ratio is tunable from approximately 5 to infinity, allowing precise control over acidity, hydrophobicity, and catalytic behavior.
| Property | Value |
|---|---|
| Framework type | FER (Ferrierite) |
| Channel system | 2D, intersecting |
| 10-MR channel | 5.4 × 4.2 Å (along [010]) |
| 8-MR channel | 3.5 × 4.8 Å (along [001]) |
| Cage type | Ferrierite cage |
| Space group | Immm (orthorhombic) |
| Si/Al ratio | 5–∞ (tunable) |
| Crystal density | ~1.95 g/cm³ |
| Unit cell parameters | a = 18.6 Å, b = 17.9 Å, c = 7.5 Å |
