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<p>Hierarchical mesoporous ZSM-5 zeolites were prepared via alkaline desilication and pillaring, and characterized by a combination of XRD, N<sub>2</sub> adsorption, <sup>29</sup>Si MAS NMR, SEM, and low-field 1D and 2D (<i>T</i><sub>1</sub>–<i>T</i><sub>2</sub> correlation) <sup>1</sup>H NMR relaxation of confined water. Alkaline treatment resulted in a&#xa0;progressive desilication, increased mesopore volume, and the formation of surface defects, whereas pillaring produced more ordered mesoporosity. The <i>T</i><sub>1</sub>–<i>T</i><sub>2</sub> correlation maps revealed distinct relaxation regimes reflecting the strength of the water–surface interactions. The samples with different mesopore organization exhibit very different surface relaxivities and <i>T</i><sub>1</sub>/<i>T</i><sub>2</sub>: as compared with the&#xa0;parent microporous zeolite, the samples with disordered mesoporosity introduced via the alkaline treatment show higher surface relaxivities but lower <i>T</i><sub>1</sub>/<i>T</i><sub>2</sub>, whereas the pillared sample, oppositely, exhibits surface relaxivities close to that of the parent sample and essentially higher <i>T</i><sub>1</sub>/<i>T</i><sub>2</sub> ratio. The decoupling of <i>T</i><sub>1</sub> and <i>T</i><sub>2</sub> points out on a complex water dynamics in the pillared zeolite with ordered micro- and mesoporosity.</p>

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Time-Domain Low Field 1H NMR Study of Water Confined in Hierarchical Mesoporous ZSM-5 Zeolites

  • 期刊论文

  • 发表日期：

    2026年7月28日

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  • Marina G. Shelyapina,
  • Dmitry Mizyulin,
  • Kirill B. Nerinovski,
  • Konstantin V. Tyutyukin,
  • Azamat Samadov,
  • Rosario I. Yocupicio‑Gaxiola,
  • Irina A. Zvereva,
  • Vitalii Petranovskii

摘要

Hierarchical mesoporous ZSM-5 zeolites were prepared via alkaline desilication and pillaring, and characterized by a combination of XRD, N2 adsorption, 29Si MAS NMR, SEM, and low-field 1D and 2D (T1–T2 correlation) 1H NMR relaxation of confined water. Alkaline treatment resulted in a progressive desilication, increased mesopore volume, and the formation of surface defects, whereas pillaring produced more ordered mesoporosity. The T1–T2 correlation maps revealed distinct relaxation regimes reflecting the strength of the water–surface interactions. The samples with different mesopore organization exhibit very different surface relaxivities and T1/T2: as compared with the parent microporous zeolite, the samples with disordered mesoporosity introduced via the alkaline treatment show higher surface relaxivities but lower T1/T2, whereas the pillared sample, oppositely, exhibits surface relaxivities close to that of the parent sample and essentially higher T1/T2 ratio. The decoupling of T1 and T2 points out on a complex water dynamics in the pillared zeolite with ordered micro- and mesoporosity.