Synthesis and Characterization of Highly Stable Nano-Sized Y Zeolite

Nano-sized Y zeolite has attracted increasing attention in the petroleum refining industry due to its excellent diffusion properties and abundant external surface acid sites. However， synthesizing highly stable nanosized Y zeolite still remains challenging. A novel hydrothermal crystallization method was developed using inexpensive anionic surfactant ammonium fatty alcohol ether sulfate （AESA） as a template agent. The synthesis involved a strategy of multiple gel formation steps， multi-stage crystallization， and post-addition of silicon source. The effects of synthesis conditions， AESA/Al2O3 ratio， and Na2O/Al2O3 ratio on the morphology and physicochemical properties of the zeolite were investigated. The synthesized materials were characterized by powder X-ray diffraction （XRD）， X-ray fluorescence spectroscopy （XRF）， N₂ physisorption fourier transform infrared spectroscopy （FT-IR）， pyridine-adsorbed FT-IR （Py-FTIR）， solid-state NMR （29Si MAS NMR and 27Al MAS NMR）， scanning electron microscopy （SEM）， transmission electron microscopy （TEM）， and EDS-mapping. The hydrothermal stability at high temperatures was compared between the nano-sized Y and commercial Y zeolites. The results demonstrate that under optimized synthesis conditions， the nano-sized zeolite exhibits an average particle size of 83 nm， a silica-alumina ratio （SAR） of 5.8， a unit cell parameter of 24.62 Å， and a specific surface area of 887 m²/g. After hydrothermal treatment at 600 °C， the reduction rate of relative crystallinity was 16.0%， which recovered to 7.1% after acid treatment. Compared to commercial Y zeolite， the nano-sized Y zeolite possesses highly developed secondary pore structure （pore size distribution mainly in the 10~80 nm range）， retains more acid sites， and exhibits superior stability， which were attributed to its improved framework integrity and higher SAR.