Hydrothermal Stability of One-Dimensional Pore ZSM-22 Zeolite in Hot Water

Anas K. Jamil, Oki Muraza, Ryota Osuga, Emad N. Shafei, Ki Hyouk Choi, Zain H. Yamani, Ali Somali, Toshiyuki Yokoi

Research output: Contribution to journalArticlepeer-review

Abstract

The hydrothermal stability of 1-D medium pore zeolites ZSM-22 with different nominal Si/Al ratios (30, 46, 80, and 100) was investigated in hot liquid water environments at different temperatures (100, 150, 200, and 250 °C) and different exposure times (6, 12, 36, 72, and 144 h). The changes in the zeolite structure, phase transformation, and textural properties were characterized by X-ray diffraction, scanning electron microscopy, 27Al and 29Si magic-angle spinning nuclear magnetic resonance, temperature-programmed desorption of ammonia, IR spectra, and X-ray fluorescence. After the treatment in a hot water environment, TON framework suffered from desilication (silicon extraction), phase transformation, and crystallinity change. The degree of desilication via siloxane hydrolysis is dependent on the treatment time and temperature. At high temperature (250 °C), severe desilication, textural properties degradation, and formation of extra-framework Al species (EFAL) were observed. This formed EFAL worked as a covering layer protecting the venerable Si bonds and mitigated further leaching of Si species from TON framework with time progress. On the contrary, selective removal of Si species at temperatures lower than 250 °C was observed without the appearance of EFAL.

Original languageEnglish
Pages (from-to)22918-22926
Number of pages9
JournalJournal of Physical Chemistry C
Volume120
Issue number40
DOIs
Publication statusPublished - 2016 Oct 13
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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