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Acidic properties of nanolayered ZSM-5 zeolites
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Wu, Leilei, Magusin, Pieter C. M. M., Degirmenci, Volkan, Li, Meiqin, Almutairi, Sami M. T., Zhu, Xiaochun, Mezari, Brahim and Hensen, Emiel J. M. (2014) Acidic properties of nanolayered ZSM-5 zeolites. Microporous and Mesoporous Materials, Volume 189 . pp. 144-157. doi:10.1016/j.micromeso.2013.08.042 ISSN 1387-1811.
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Official URL: http://dx.doi.org/10.1016/j.micromeso.2013.08.042
Abstract
The acidic properties of nanolayered ZSM-5 zeolites synthesized with the aid of multiquaternary ammonium surfactants were investigated in detail. A substantial fraction of Al is present in highly dispersed form at extraframework positions indicative of the defective nature of the calcined nanolayered zeolites. Acidity characterization reveals that the Brønsted acid sites are similar in strength to those in bulk HZSM-5. Nanolayered zeolites contain a higher amount of Brønsted acid sites (BAS) at their external (mesopore) surface. Unilamellar zeolites have a higher concentration of external BA and silanol sites than multilamellar ones. The number of BAS in the nanolayered zeolites is considerably lower than the tetrahedral Al content, the difference increasing with nanolayer thickness. Except for one particular sample (nanolayered ZSM-5 synthesized from C22-6-6OH2 template), the total turnover of methanol normalized per BAS trends inversely with the concentration of BAS. There is no correlation with the concentration of external BAS. Catalyst deactivation due to coke mainly depends on the BAS concentration. A unilamellar ZSM-5 zeolite prepared using C22-6-6OH2 displayed substantially improved performance in terms of a much lower rate of coke deactivation in line with earlier data Choi et al. [10]. Since the acidic and textural properties of this zeolite did not differ significantly from the others, it remains to be determined why this zeolite performs so much better.
Item Type: | Journal Article | ||||||
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Divisions: | Faculty of Science, Engineering and Medicine > Engineering > Engineering | ||||||
Journal or Publication Title: | Microporous and Mesoporous Materials | ||||||
Publisher: | Elsevier Science BV | ||||||
ISSN: | 1387-1811 | ||||||
Official Date: | 1 May 2014 | ||||||
Dates: |
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Volume: | Volume 189 | ||||||
Page Range: | pp. 144-157 | ||||||
DOI: | 10.1016/j.micromeso.2013.08.042 | ||||||
Status: | Peer Reviewed | ||||||
Publication Status: | Published | ||||||
Access rights to Published version: | Restricted or Subscription Access |
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