Natural zeolites occur in over 40 countries and are mined in 11 of these at a rate of around 250 thousand tonnes per year. Discovery of the characteristic ion-exchange, dehydration and selective-adsorption properties of these zeolites, which are related to their unique honeycomb structure, stimulated the development of severa1 processes for the manufacture of synthetic zeolites. These synthetic...

The recently proposed united atom force field by Dubbeldam et al. (Phys. Rev. Lett. 2004, 93, 088302) for the adsorption of alkanes in MFI-type zeolites was extended to other zeolites in this work. Its applicability to FER-type zeolites was evaluated in detail, for which the Henry coefficients, the isosteric heat of adsorption, the adsorption isotherms, as well as the locations of alkanes in th...

We study the background associated with phenomena observed in zeolites using combinatorial and geometric techniques. We define combinatorial d-dimensional zeolites and show that not all combinatorial zeolites have a unit distance realization inR , and of those that have a unit distance realization, not all have non-overlapping unit-distance realizations. Only few classes of finite 2-d zeolites ...

The direct experimental evidence shows that ethylbenzene disproportionation is a transition state shape selective reaction on zeolites: a bimolecular reaction mechanism via diphenylethane-mediated pathway on large-pore zeolites X and Y (ca. 0.74 nm) and a monomolecular reaction mechanism on medium-pore zeolites ZSM-5 (ca. 0.56 nm) via the ethoxy-mediated intermolecular ethyl group transfer. The...

A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of...

zeolites a, x and hs were synthesized from natural iranian kaolinite by alkaline fusion,,followed by refluxing the mixture. the transformation of zeolites x to hs and y to p were studied at different time intervals by x-ray diffraction and scanning electron microscopy (sem). it was revealed that in solution, zeolites hs and p are more stable than zeolites x and y respectively

Zeolites are nanoporous crystalline alumino-silicates with a rich variety of interesting properties and industrial applications. With over 140 zeolite framework topologies synthetically available—each with its own range of compositions—zeolites offer size-, shapeand electrostaticallyselective adsorption, diffusion and reaction up to remarkably high temperatures. Zeolites are widely used as petr...

Interplay of quantum mechanical calculations and experimental data on hyperfine coupling constants of ethyl radical in zeolites at several temperatures was engaged to study the geometries and binding energies and to predict the temperature dependence of hyperfine splitting of a series of alkyl radicals in zeolites for the first time. The main focus is on the hyperfine interaction of alkyl radic...

Zeolites A, X and HS were synthesized from natural Iranian Kaolinite by alkaline fusion,,followed by refluxing the mixture. The transformation of zeolites X to HS and Y to P were studied at different time intervals by X-ray diffraction and Scanning Electron Microscopy (SEM). It was revealed that in solution, zeolites HS and P are more stable than zeolites X and Y respectively

Zeolites are widely applied as solid acid catalysts in various technological processes. In this work we have computationally investigated how catalytic reactivity scales with acidity for a range of zeolites with different topologies and chemical compositions. We found that straightforward correlations are limited to zeolites with the same topology. The adsorption energies of bases such as carbo...