USY Zeolite Catalyst

USY (Ultra-Stable Y) zeolite is the primary active component in modern FCC catalysts, supplying the acid sites and hydrothermal stability required to survive regenerator conditions above 700 °C in steam. It is manufactured by dealuminating a parent Y zeolite — removing framework aluminium through steam calcination or acid treatment — which raises the framework Si/Al ratio, contracts the unit cell, and creates a secondary mesopore network that improves heavy-feed accessibility.

The result is a material that retains the 12-membered ring FAU supercage topology while trading some of the strong Brønsted acidity of HY zeolite for the thermal resilience that FCC units demand. USY is also used in hydrocracking where high-pressure H₂ and elevated temperatures require stable acid sites and resistance to framework degradation.

The current handbook supply is H-USY powder with SiO₂/Al₂O₃ 12-100, BET surface area above 500 m²/g, and primary crystal size 500-1000 nm. Rare-earth exchange, enhanced mesoporosity, microspheres, or shaped products are separate formulated requirements and must be technically confirmed.

How to Select the Right USY Zeolite Catalyst Grade

USY selection is driven by unit cell size, rare-earth exchange, and mesoporosity — not just composition.

Unit cell size (UCS) is the most practical QC parameter for FCC catalyst developers. Lower UCS (24.24–24.35 Å) correlates with higher framework Si/Al, fewer but stronger acid sites, lower hydrogen-transfer activity, and higher gasoline selectivity. Higher UCS (24.40–24.55 Å) delivers more total acidity, higher cracking activity, and richer hydrogen transfer — useful when maximum conversion or olefin saturation is the target.

Rare-earth exchange (RE-USY) increases activity and hydrogen transfer, which raises gasoline yield for maximum-gasoline FCC modes. RE-free USY is preferred when the refiner wants to maximise propylene and minimise hydrogen transfer — common in petrochemical FCC operation. Specify RE₂O₃ level (typically 0 to 5+ wt%) based on your product slate target.

Mesoporosity from dealumination creates 20–500 Å secondary pores that help heavy feed molecules reach acid sites without excessive cracking. Higher mesopore volume improves bottoms conversion and metals tolerance but can reduce microporous surface area. For resid FCC or heavy hydrocracking feeds, ask about mesopore-enhanced grades.

SiO₂/Al₂O₃ ratio is the bulk composition parameter. The current catalogue bands are 12-15, 20-25, 30-35, 50-70, and 80-100. Choose a band against feed, activity, stability, and formulation requirements.

Current USY Supply Range

Key Specifications

COA data for every shipment can include SiO₂/Al₂O₃ ratio, UCS, BET surface area, Na₂O, RE₂O₃, mesopore volume, particle size distribution, and XRD crystallinity.

FCC: The Primary Application

USY is the core cracking component in FCC catalysts worldwide. Its FAU supercages crack heavy gas oil molecules into gasoline, LPG, and light olefins, while the dealuminated framework survives repeated oxidation-reduction cycles in the regenerator at 700–800 °C.

The UCS you select directly shapes FCC unit economics. Refineries maximising gasoline will choose RE-USY with UCS 24.40+ to promote hydrogen transfer and saturate olefins. Refineries maximising propylene will select RE-free USY with UCS 24.30-24.38 to reduce hydrogen transfer and preserve light olefins. Mesopore-enhanced USY is recommended for resid FCC units where metals tolerance and bottoms cracking are limiting.

For a detailed application guide, see USY for FCC and the FCC catalyst selection guide.

Hydrocracking

USY is used in hydrocracking catalysts where high-pressure H₂ environments demand stable acid sites. The mesoporosity from dealumination benefits heavy-feed hydrocracking by improving diffusion of large molecules to active sites. USY with higher SAR (30-80+) is preferred for hydrocracking because the reduced acid density helps control over-cracking and coke formation.

Specify whether you need USY powder for catalyst formulation or pre-shaped extrudates. Binder selection and metal loading will affect final performance more than the zeolite alone, so plan to evaluate USY in a formulated catalyst rather than as a standalone powder.

Performance Notes: Steam Stability and UCS Control

USY owes its commercial value to one property above all others: steam stability. A non-dealuminated HY zeolite would lose most of its crystallinity and acidity within hours under FCC regenerator conditions. USY survives because dealumination removes the most hydrolysis-susceptible framework aluminium atoms, stabilising the remaining lattice.

The relationship between UCS and performance is well-established: each 0.01 Å reduction in UCS reflects measurable framework dealumination and shifts the activity-selectivity balance. FCC operations that track equilibrium catalyst UCS alongside MAT activity can detect shifts in unit performance before they affect yield. For catalyst developers, UCS is the most actionable single QC parameter — specify your target UCS window when requesting a USY sample.

HY vs USY

HY zeolite and USY share the FAU framework but occupy opposite ends of the acidity-stability spectrum. HY provides maximum Brønsted acidity from proton-exchanged Y zeolite without dealumination, suitable for FCC active matrix and fine-chemical acid catalysis. USY sacrifices some of that acidity for the hydrothermal resilience that FCC and hydrocracking require.

For the full comparison, see HY vs USY. If your process runs above 500 °C in the presence of steam, start your evaluation with USY.

Technical Documents

Download the USY TDS for SiO₂/Al₂O₃, UCS, BET, mesopore volume, Na₂O, RE₂O₃, particle size, and XRD data.

When requesting a sample, specify your target UCS window, SiO₂/Al₂O₃ ratio, RE₂O₃ level (if any), and whether you need powder, microspheres, or extrudates.