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Hierarchical Y and USY Zeolites Designed by Post‐Synthetic Strategies
Author(s) -
Verboekend Danny,
Vilé Gianvito,
PérezRamírez Javier
Publication year - 2012
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201102411
Subject(s) - zeolite , microporous material , crystallinity , mesoporous material , materials science , chemical engineering , catalysis , dissolution , inorganic chemistry , chemistry , organic chemistry , composite material , engineering
Strategic combinations of affordable and scalable post‐synthetic modifications enabled to design a broad family of hierarchical Y and USY zeolites (FAU topology) independent on the Si/Al ratio. Pristine (Y, Si/Al = 2.4), steamed (USY, Si/Al = 2.6), and steamed and dealuminated (USY, Si/Al = 15 and 30) zeolites were exposed to a variety of acid (H 4 EDTA and Na 2 H 2 EDTA) and base (NaOH) treatments, which led to the introduction of mesopore surfaces up to 500 m 2 g −1 , while preserving the intrinsic zeolite properties. Pristine Y and USY zeolites (Si/Al ∼ 2.5) required mild dealumination (to Si/Al > 4 in the case of Y) to facilitate subsequent efficient desilication. Alkaline treatment of Y and USY zeolites with low Si/Al ratios (∼4–6) led to an abundance of Al‐rich debris, which could be removed by a subsequent mild acid wash. On the other hand, severely steamed and dealuminated, hence Si‐rich, USY zeolites (Si/Al = 15 and 30) proved extremely sensitive to the alkaline solution, displaying facile dissolution and substantial amorphization. For the latter group of ultra‐stable Y zeolites, the presence of TPA + in the alkaline solution enables to protect the zeolite structures upon the introduction of mesoporosity by desilication, preserving crystallinity and micropore volume. The sorption and catalytic properties of the hierarchical Y and USY zeolites were superior compared to the conventional counterparts.