Pressure-induced penetration of guest molecules in high-silica zeolites: the case of mordenite
Authors: Arletti R., Leardini L., Vezzalini G., Quartieri S., Gigli L., Santoro M., Haines J., Rouquette J., Konczewicz L.
Autors Affiliation: Univ Turin, Dipartimento Sci Terra, I-10125 Turin, Italy; Interdept Ctr Nanostruct Interfaces & Surfaces NI, I-10135 Turin, Italy; Univ Messina, Dipartimento Fis & Sci Terra, I-98166 Messina S Agata, Italy; Univ Modena & Reggio Emilia, Dipartimento Sci Chim & Geol, I-41125 Modena, Italy; CNR, Ist Nazl Ott, I-50019 Sesto Fiorentino, Italy; European Lab Non Linear Spect LENS, I-50019 Sesto Fiorentino, Italy; Univ Montpellier, Equipe C2M, UMR CNRS 5253, Inst Charles Gerhardt Montpellier, F-34095 Montpellier 5, France; Univ Montpellier, Lab Charles Coulomb, UMR CNRS 5221, F-34095 Montpellier 5, France
Abstract: A synthetic high-silica mordenite (HS-MOR) has been compressed in both non-penetrating (silicone oil, s.o.) and penetrating [methanol : ethanol : water (16 : 3 : 1) (m.e.w.), water : ethanol (3 : 1) (w.e.), and ethylene glycol (e.gl.)] pressure transmitting media (PTM). In situ high-pressure (HP) synchrotron X-ray powder diffraction (XRPD) experiments allowed the unit cell parameters to be followed up to 1.6, 1.8, 8.4, and 6.7 GPa in s.o., w.e., m.e.w., and e.gl., respectively. Moreover, e.gl. was also used as a PTM in in situ HP Raman and ex situ IR experiments. The structural refinement of HS-MOR compressed in e.gl. at 0.1 GPa – the lowest investigated pressure – revealed the presence of 3.5 ethylene glycol molecules per unit cell. The infrared spectrum of the recovered sample, after compression to 1 GPa, is consistent with the insertion of ethylene glycol molecules in the pores. XRPD and Raman spectroscopy experiments performed under pressure indicated the insertion of a small number of guest molecules. Ethylene glycol is partially retained inside mordenite upon pressure release. A symmetry lowering was observed in s.o. above 0.8 GPa, while above 1.6 GPa the patterns indicated a rapid loss of long range order. From ambient pressure (Pamb) to 1.6 GPa, a high cell volume contraction (Delta V = -9.5%) was determined. The patterns collected with penetrating PTM suggested the penetration of guest molecules into the porous host matrix, starting from a very low P regime. The entrapment of PTM molecules inside micropores contributes to the stiffening of the structure and, as a consequence, to the decrease of the compressibility with respect to that measured in s.o. From the structural point of view, HS-MOR reacts to compression and to the penetration of different guest species with appropriate framework deformations. Interestingly, ethylene glycol is partially retained inside mordenite upon pressure release, which is of importance for potential application of this composite material.
Journal/Review: PHYSICAL CHEMISTRY CHEMICAL PHYSICS (PRINT)
Volume: 17 (37) Pages from: 24262 to: 24274
KeyWords: SYNCHROTRON POWDER DIFFRACTION; INDUCED OVER-HYDRATION; INDUCED AMORPHIZATION; ELASTIC BEHAVIOR; WATER INTRUSION; NA-A; DEFORMATION MECHANISM; MICROPOROUS MATERIALS; LI-A; ADSORPTIONDOI: 10.1039/c5cp03561aCitations: 15data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2021-10-24References taken from IsiWeb of Knowledge: (subscribers only)Connecting to view paper tab on IsiWeb: Click hereConnecting to view citations from IsiWeb: Click here