Structural, compositional and acidic characteristics of nanosized amorphous or partially crystalline ZSM-5 zeolite-based materials

Kostas S. Triantafyllidis*, Lori Nalbandian, Pantelis N. Trikalitis, Athanasios K. Ladavos, Thomas Mavromoustakos, Christakis P. Nicolaides

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

Partially crystalline and X-ray amorphous ZSM-5 zeolite-based aluminosilicates have been synthesized and thoroughly characterized by chemical analysis, XRD, FT-IR, solid state MAS NMR, N2 adsorption, TEM, NH3-TPD and isopropanol dehydration as the catalytic test reaction. The X-ray amorphous and low-crystallinity samples were hydrothermally synthesized at temperatures as low as 25°C and consisted of nanosized well-formed particles of almost spherical shape and with dimensions of about 20-30 nm. These samples exhibited very low microporosity and remarkably high meso/macropore volume (pore diameters ≥30nm) and/or high external surface area. The first Bragg peaks were observed in the XRD patterns of the samples synthesized at 90°C and their position on the 2θ-axis was the same as those of a reference highly crystalline ZSM-5 zeolite sample. The particle/crystal size and microporosity of the partially crystalline materials increased with increasing hydrothermal synthesis temperature and % relative XRD crystallinity. Incorporation of aluminum in the ZSM-5 zeolitic framework was significantly enhanced at higher relative crystallinities, i.e. >60%. The X-ray amorphous aluminosilicates possessed tetrahedral aluminum atoms which were more zeolitic in character and induced a higher number of acidic framework hydroxyls (Brønsted acid sites), as compared to those found in a con-ventional silica-alumina.

Original languageEnglish
Pages (from-to)89-100
Number of pages12
JournalMicroporous and Mesoporous Materials
Volume75
Issue number1-2
DOIs
StatePublished - 12 Oct 2004
Externally publishedYes

Keywords

  • Acidity
  • Framework aluminum
  • Nanosized zeolites
  • Partially crystalline ZSM-5
  • Porosity

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials

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