NH4-SSZ-13 is etched with an aqueous solution of 40 w/% NH4F under different time/temperature conditions to obtain hierarchical derivatives. The zeolites are characterized by XRD, SEM, N2 physisorption, 29Si/27Al/19F MAS NMR, ICP-AES, and their acidity monitored in situ FTIR spectroscopy using acetonitrile as a probe molecule. results highlight that the zeolite very sensitive high temperature l...

Phenol is an important industrial intermediate for the production of various chemicals such as bisphenol A, phenolic resins, caprolactam, alkylphenols and adipic acid. The cumene hydroperoxide process is the currently used industrial method to produce phenol. Its environmentally stressing aspects have spurred research to replace this process with more benign approaches such as the direct oxidat...

The electrostatic potential (EP) and electric field (EF) are calculated in the TON and CHA zeolites using periodic hybrid B3LYP, PBE, and PW91 functionals considering eight basis sets. Relative root mean square differences between the EP or EF values estimated between the different basis sets are evaluated in several domains available for adsorbate molecules in both zeolites. The EP is interpre...

The main interaction between pyridine and zeolites leads to form a hydrogen bond between the N atom of pyridine and OH groups of zeolites. The present work reports a theoretical study about the structural, vibrational and topological properties of the charge distribution of the molecular complexes between pyridine and a series of acids sites of zeolites. The calculated structural parameters...

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...

Molecular-sieve zeolites, Nafion membranes, low-density polyethylene films, and mixed surfactant vesicles have been used as microreactors to carry out organic photochemical reactions. The photo-cycloadditions of diaryl compounds with long flexible chains included in NaY zeolite or low-density polyethylene films yield intramolecular photocyclomers to the exclusion of intermolecular products. The...