Hydrogen bonding to oxygen in siloxane bonds drives liquid phase adsorption of primary alcohols in high-silica zeolites

Abstract

Upon liquid phase adsorption of C1-C5 primary alcohols on high silica MFI zeolites (Si/Al = 11.5-140), the concentration of adsorbed molecules largely exceeds the concentration of traditional adsorption sites: Brønsted...

Polysilicate Porous Organic Polymers (PSiPOPs), a Family of Porous, Ordered 3D Reticular Materials with Polysilicate Nodes and Organic Linkers

“…Since X-ray diffraction demonstrated the exclusive presence of amorphous material (Figures SI-2–SI-4), the reticular network was elucidated using an NMR crystallography approach (Figure ). − …”

Noncontact In Situ Multidiagnostic NMR/Dielectric Spectroscopy

“…As an example of the applicability of the developed methodology for investigating solvent–surface interactions and the physicochemical properties of confined systems, water confined in the micropores of an MFI-11.5 zeolite has been investigated. While defect-free all-silica MFI zeolites are highly hydrophobic materials, the framework defects and Bro̷nsted acid sites (BAS) in Al-substituted zeolites such as MFI-11.5 facilitate water intrusion, with water being adsorbed in these hydrophilic sites . The 1 H NMR spectrum and the average dielectric permittivity of water in the micropores of MFI-11.5 are depicted in Figure for different hydration levels.…”

“…Since the degree of reorganization of the water network is dependent on the surface chemistry, determination of the change in dielectric properties of the intruded water offers a versatile methodology to characterize the influence of specific surface chemistry. This, in combination with the possibility of simultaneous access to quantitative atomic-level information about speciation, interactions, dynamics, etc., from the NMR spectra, ,, makes the developed methodology a versatile surface characterization technique for characterizing and generating structure–function relationships for a wide variety of porous materials like zeolites, periodic mesoporous silicas, organo silicas, etc., with applications ranging from catalysis, adsorption, and energy storage.…”

“…Characterization of interfacial interactions is, however, extremely tedious, especially in 3D porous materials such as zeolites, mesoporous silicates, metal–organic frameworks (MOFs), and covalent organic frameworks (COFs). Such materials are nevertheless abundantly implemented in chemical applications, − in molecular water research, , and for energy storage applications. − Specifically for zeolites, solvent (e.g., water, alcohol) pore wall interactions impact catalysis and adsorption processes. , …”

“…Not only is NMR characterization nearly unaffected by the length scale of periodicity, with the advent of high-pressure magic-angle spinning (MAS), , but also high-pressure in situ MAS NMR studies of nanoconfined water systems are within reach. NMR probes local chemical composition and provides molecular-level information on molecular dynamics and intermolecular interactions, including those of and with the confining host material. ,− It yields absolute quantification ( 1 H, 2 H, 13 C, 29 Si, 17 O,···) and probes the local chemical environment of H 2 and H 2 O molecules and their deuterated forms. − While NMR is focused on local atomic-level characterization, dielectric relaxation spectroscopy (DRS), the time-domain variant of electrochemical impedance spectroscopy (EIS), yields medium-to-long-range information on the confined water phase and its phase transitions . For water confined in hydrophobic mesoporous (organo-)­silicas, for example, DRS revealed a nonfreezable water layer at the pore wall/water interface, demonstrating layering of the confined water .…”