TY - JOUR

T1 - Nanoconfined Water in Pillared Zeolites Probed by 1H Nuclear Magnetic Resonance

AU - Shelyapina, Marina

AU - Nefedov, Denis

AU - Antonenko, Anastasiia

AU - Valkovskii, Gleb

AU - Yocupicio-Gaxiola, Rosario I.

AU - Petranovskii, Vitalii

PY - 2023/11/2

Y1 - 2023/11/2

N2 - Here, we report the results of our 1H nuclear magnetic resonance study of the dynamics of water molecules confined in zeolites (mordenite and ZSM-5 structures) with hierarchical porosity (micropores in zeolite lamella and mesopores formed by amorphous SiO 2 in the inter-lamellar space). 1H nuclear magnetic resonance (NMR) spectra show that water experiences complex behavior within the temperature range from 173 to 298 K. The temperature dependence of 1H spin-lattice relaxation evidences the presence of three processes with different activation energies: freezing (about 30 kJ/mol), fast rotation (about 10 kJ/mol), and translational motion of water molecules (23.6 and 26.0 kJ/mol for pillared mordenite and ZSM-5, respectively). For translational motion, the activation energy is markedly lower than for water in mesoporous silica or zeolites with similar mesopore size but with disordered secondary porosity. This indicates that the process of water diffusion in zeolites with hierarchical porosity is governed not only by the presence of mesopores, but also by the mutual arrangement of meso- and micropores. The translational motion of water molecules is determined mainly by zeolite micropores.

AB - Here, we report the results of our 1H nuclear magnetic resonance study of the dynamics of water molecules confined in zeolites (mordenite and ZSM-5 structures) with hierarchical porosity (micropores in zeolite lamella and mesopores formed by amorphous SiO 2 in the inter-lamellar space). 1H nuclear magnetic resonance (NMR) spectra show that water experiences complex behavior within the temperature range from 173 to 298 K. The temperature dependence of 1H spin-lattice relaxation evidences the presence of three processes with different activation energies: freezing (about 30 kJ/mol), fast rotation (about 10 kJ/mol), and translational motion of water molecules (23.6 and 26.0 kJ/mol for pillared mordenite and ZSM-5, respectively). For translational motion, the activation energy is markedly lower than for water in mesoporous silica or zeolites with similar mesopore size but with disordered secondary porosity. This indicates that the process of water diffusion in zeolites with hierarchical porosity is governed not only by the presence of mesopores, but also by the mutual arrangement of meso- and micropores. The translational motion of water molecules is determined mainly by zeolite micropores.

KW - иерархические цеолиты

KW - морденит

KW - ZSM-5

KW - динамика молекул воды

KW - ЯМР

KW - Zeolites/chemistry

KW - Silicon Dioxide/chemistry

KW - Water/chemistry

KW - Magnetic Resonance Spectroscopy/methods

KW - hierarchical zeolites

KW - ZSM-5

KW - water dynamics

KW - mordenite

KW - proton NMR

UR - https://www.mendeley.com/catalogue/01fb687a-a7e2-36c3-a253-5330c239e01d/

U2 - 10.3390/ijms242115898

DO - 10.3390/ijms242115898

M3 - Article

C2 - 37958879

VL - 24

JO - International Journal of Molecular Sciences

JF - International Journal of Molecular Sciences

SN - 1422-0067

IS - 21

M1 - 15898

ER -