Amorphization of USY zeolite induced by sodium chloride and high temperature steaming

• Published in: Microporous and mesoporous materials Vol. 224; pp. 168 - 175
• Main Authors: Sandoval-Díaz, Luis-Ernesto, Ruíz-Cardona, Yefferson-Stid, Trujillo, Carlos-Alexander
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.04.2016
• Subjects: Desilication; Sodium chloride contamination; Steaming; USY zeolite; Zeolite amorphization; Zeolite amorphization; USY zeolite; Desilication; Sodium chloride contamination; Steaming
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2015.11.021

The present study shows the effect of sodium contamination over the structural evolution of USY under conditions similar to the regenerator of an FCC unit. Increasing loads of Na+ (as NaCl) were added on a sample of commercial USY, and the admixtures were treated at fixed hydrothermal conditions. Sample evolution was followed by powder X-ray diffraction (XRD), Raman spectroscopy, nitrogen sorptometry, and scanning electron microscopy (SEM). The results of this research show that the materials amorphize irreversibly with increasing Na+ level, with a marked loss of microporosity, but interestingly, without a substantial depletion of framework aluminum. The structural map of the outcoming samples was figured out by XRD and Raman scattering experiments, showing that at the molecular scale the destruction occurs selectively on faujasite six-membered rings. [Display omitted] •USY zeolite was loaded with increasing amounts of NaCl and steamed at the typical temperature of a FCC regenerator.•The samples exhibit a gradual deterioration of the texture and crystal properties with increasing load.•The amorphization occurs by consuming NaCl and by evolution of HCl from the reactive media.•The destruction seems to occur preferentially on six-member rings of the FAU structure.