Defect sites in zeolites: origin and healing

Palčić, Ana; Moldovan, Simona; El Siblani, Hussein; Vicente, Aurelie; Valtchev, Valentin (2021) Defect sites in zeolites: origin and healing. Advanced Science, 9 (4). ISSN 2198-3844

Preview

PDF - Published Version - article Available under License Creative Commons Attribution. Download (3MB) | Preview

Abstract

This paper deals with the synthesis conditions–defect formation relationship in zeolites. Silicalite-1 (MFI-type) is used as a model material. Samples synthesized from a system with high basicity (at 100 °C), a system with moderate basicity (at 150 °C), and a fluoride- containing system in neutral medium (at 170 °C) were compared. Well-crystallized materials with sizes ca. 0.1, 1-10, and 30-40 µm were obtained. The samples are analyzed by complementary methods providing information on the short- and long-range order in the zeolite framework. A strong correlation between the number of point defects in the zeolite framework and preparation conditions is established. Silicalite-1 synthesized under mild synthesis conditions from a highly basic system exhibits a larger number of framework defects and thus low hydrophobicity. Further, the calcined samples were subjected to aluminum and silicon incorporation by post- synthesis treatment. The Al/Si incorporation in the zeolite framework and its impact on the physicochemical properties is studied by XRD, TEM/SEM, solid-state NMR, FTIR, and thermogravimetric analyses. The defects healing as a function of the number of point defects in the initial material and zeolite crystal size is evaluated. The results of this study will serve for fine-tuning zeolite properties by in situ and post-synthesis methods.

Item Type:	Article
Uncontrolled Keywords:	zeolites ; defect sites ; silanols ; post-synthesis treatment ; Al/Si incorporation
Subjects:	NATURAL SCIENCES > Chemistry
Divisions:	Division of Materials Chemistry
Depositing User:	Ana Palčić
Date Deposited:	22 Feb 2022 09:49
URI:	http://fulir.irb.hr/id/eprint/7013
DOI:	10.1002/advs.202104414

Actions (login required)

View Item