One-dimensional medium-pore zeolites are promising catalysts for propylene production from naphtha cracking due to their high selectivity. However, fast deactivation pore mouth blockage is preventing these being widely used in commercial applications. In this study, we molecular dynamics simulations investigate the diffusion of three one-dimensional aluminosilicate frameworks (ZSM-23, ZSM-22, Z...

This article reviews recently published work showing how inelastic neutron scattering spectroscopy can be used to identify species found in zeolite ZSM-5 as a catalyst for conversion of methanol hydrocarbons. The advantages and disadvantages the technique are illustrated, current challenges identified.

Self-di!usion in zeolites is studied using a simple mean-"eld theory and dynamic Monte-Carlo simulations of di!usion on a lattice model of the zeolite pore space. Our method is powerful, because of its simplicity, #exibility and ability to study the in#uence of various factors: the topology of the pore network, the fraction of strong adsorption sites, the relative strengths of weak and strong s...

Zeolite catalysis is determined by a combination of pore architecture and Brønsted acidity. As Brønsted acid sites are formed by the substitution of AlO4 for SiO4 tetrahedra, it is of utmost importance to have information on the number as well as the location and neighbouring sites of framework aluminium. Unfortunately, such detailed information has not yet been obtained, mainly due to the lack...

Two NMR techniques, zH MAS NMR and echo Fourier 27AI NMR, have been applied for the first time to the investigation of Bronsted sites in dehydrated hydrogen forms ofzeolites. The “AI signal of SiOHAl sites, which was “NMR-invisible” until now, yields a quadrupole coupling constant C,,= 16 MHz for the dehydrated zeolite H-ZSM-5. The values of C,, determined from the ZH MAS NMR spectra of SiODAl ...

Kaolin with alumina and silica content is used as the main material in this research to study synthesis of ZSM-5 zeolite. The hydrothermal process was carried out through different aging times, namely 12, 24 36 hours. Tetrapropyl ammonium bromide (TPABr) a template for Mobile Five-1 (MFI) structure guide. X-ray diffraction (XRD) infrared spectroscopy (FTIR) instruments were characterize zeolite...

Adsorption of glycine on the acid site of H-ZSM-5 has been studied at an embedded ONIOM (MP2/6-31G(d,p): UFF) level of theory. Four possible modes of adsorptions are considered. The zwitterionic adsorption is the most stable conformation with the highest adsorption energy of 47.22 kcal/mol. The glycine zwitterion is protonated and stabilized by the anionic zeolite framework. The second most sta...

in the present work, b-zsm-5 zeolite membranes were synthesized on porous tubular α-alumina supports by several subsequence in situ crystallization hydrothermal treatments. the tio2- bohmite and ɣ- alumina intermediate layers were applied to improve the lattice matching between zeolite layer and the support. the uniform membrane intermediate layers with low permeation resistance were prepared o...