This sixty-eighth volume of IARC Monographs considers certain forms of crystalIine and amorphous silica, some silicates (palygorskite, also called attapulgite; sepiolite; wollastonite; and some natura1 and synthetic zeolites, exc1uding erionite), coa1 dust and para-aramid fibrils. Some of these agents are fibrous in nature (palygorskite, sepiolite, wollastonite and sorne natural zeolites, as we...

Serial femtosecond crystallography (SFX) is capable of collecting three-dimensional single-crystal diffraction data using polycrystalline samples. This may dramatically enhance the power of X-ray powder diffraction. In this paper a test has been performed using simulated diffraction patterns. The test sample is a mixture of two zeolites with crystal grain sizes from 100 to 300 nm. X-ray diffrac...

1. Introduction Diffusion is important in many technological processes, particularly those that utilize nanoporous materials like zeolites for adsorptive separations and catalysis, where mass transfer is often the rate-limiting step. For understanding and predicting such processes knowledge of the adsorption and diffusion behaviour of molecular mixtures is essential. It is known, that branched ...

Zeolites are the best known microporous molecular sieves and adsorbe molecules below a particular size in their pore structures. Therefore they are considered as heterogenous catalysts and sorbents [1]. The catalytic properties of zeolites can be understood by investigating the adsorption characteristics of reactions on their surfaces [2, 3]. During the past years the adsorption of some compoun...

Micro/mesoporous zeolitic composites (MZCs) represent an important class of hierarchical zeolitic materials that have attracted increasing attention in recent years. By introducing an additional mesoporous phase interconnected with the microporosity of zeolites, a hierarchical porous system of MZCs is formed which facilitates molecular transport while preserving the intrinsic catalytic properti...

Faujasite (X, Y, and USY) zeolites represent one of the most widely-applied and abundant catalysts and sorbents in the chemical industry. In the last 5 years substantial progress was made in the synthesis, characterisation, and catalytic exploitation of hierarchically-structured variants of these zeolites. Hererin, we provide an overview of these contributions, highlighting the main advancement...

Zeolites with the faujasite structure (FAU) are extensively used as catalysts and in gas separation. A detailed knowledge of their structure, particularly the positions of extra−framework cations in the case of gas adsorption, is therefore central to understanding their performance. Typically zeolites X (Si/Al ~.1.1−1.5) and Y (Si/Al ~5−11) are used. A common assertion of structural determinati...

The chemistry of radicals adsorbed on zeolites is remarkable in that the products of radical-radical reactions, which are nonselective in solution, can be made selective and can be controlled by supramolecular effects and magnetic isotope effects. The photolysis of ketones adsorbed on zeolites can be manipulated so that either primary or secondary radicals produced by photolysis can be directed...

We have investigated various silica zeolites using density functional theory with periodic supercells, plane waves, and pseudopotentials. These zeolitic phases include silica sodalite, chabazite, mordenite, silica LTA, and silicalite. Atom-level geometries, elastic properties, and cohesive energies are presented. Although the zeolites exhibit a wide range of Si-O-Si angles and densities, the co...

guishing high and low Si/Al ratio zeolites and may be important in studies of zeolites that are chemically or physically altered. ence Foundation under Grant CHE 8204417 is gratefully acknowledged. We thank Professor T. L. Barr, Professor J. Vedrine, Dr. C. D. Wagner, Dr. J. M. Stencel, and Dr. T. D. Debies for helpful discussions and for their comments and suggestions concerning this manuscrip...