The location of p-xylene in a single crystal of zeolite H-ZSM-5 with a new, sorbate-induced, orthorhombic framework symmetry

Molecular modeling of binary liquid‐phase adsorption of aromatics in silicalite

“…The energies in the intersections and zigzag channels are Ϫ60.1 and Ϫ71.9 kJ/mol, respectively. p-xylene molecules at the intersection orient themselves such that the methyl groups point to the straight channel sections, in agreement with experimental observations in the literature (van Koningsveld et al, 1989;Mentzen and Vignemaeder, 1987). Molecules in the zigzag sections orient so that the methyl groups point toward the intersections.…”

“…The as-synthesized form of silicalite is called OR-THO silicalite. It was also found that silicalite may exist in another form referred to as PARA (van Koningsveld et al, 1989). PARA silicalite has the same connectivity and channel structure as ORTHO silicalite, but slight differences in pore size and shape lead to remarkable changes in adsorption characteristics of aromatic molecules.…”

“…Many authors have experimentally studied the adsorption of p-xylene in silicalite by techniques such as X-Ray diffraction, FT-Raman spectroscopy, and NMR (Fyfe et al, 1984;van Koningsveld et al, 1989;Mentzen and Vignemaeder, 1987;Ashtekar et al, 1998;Huang, 1996). Below the loading of four molecules per unit cell, it is found that p-xylene adsorbs at the intersections.…”

“…PARA silicalite has the same connectivity and channel structure as ORTHO silicalite, but slight differences in pore size and shape lead to remarkable changes in adsorption characteristics of aromatic molecules. It is known that on adsorption of more than 4 molecules of p-xylene per unit cell silicalite changes from ORTHO to PARA (van Koningsveld et al, 1989;Fyfe et al, 1984). Single component adsorption of benzene and p-xylene in silicalite both in PARA and ORTHO form have been studied previously (Snurr et al, 1993b), and, based on several observations, it was argued that silicalite changes from ORTHO to PARA also upon adsorption of more than four molecules per unit cell of benzene.…”

Adsorption mechanism of 1,2-dichloroethane into an organophilic zeolite mordenite: A combined diffractometric and gas chromatographic study

“…In the present work, a structural investigation was performed to highlight the adsorption mechanisms in order to select the appropriate isotherm model. X-ray and neutron diffraction techniques are usually employed to characterise the structure of zeolites loaded with hydrocarbon guest species in order to clearly locate their position inside the channel system [28], [29], [30], [31], [32], [33], [34], [35] and [36]. Unfortunately, these experiments are generally performed at low temperatures by incorporating hydrocarbons using the gas phase.…”