mfi-type zeolite membranes (zsm-5) were prepared on α-alumina tubular supports and tested for separation of h2/co mixtures. the effect of pressure and temperature on h2 and co flows and selectivity was investigated. the best results in this work were obtained with a zsm-5 membrane prepared over a porous α-alumina tube seeded with zeolite nanocrystals synthesized with microwave technique. in thi...

Hierarchical zeolite monoliths with multimodal porosity are of paramount importance as they open up new horizons for advanced applications. So far, hierarchical zeolites based on nanotube scaffolds have never been reported. Inspired by the organization of biominerals, we have developed a novel precursor scaffolding-solid phase crystallization strategy for hierarchical zeolites with a unique nan...

Proton-energy differences, ammonia adsorption, and D/H-exchange barriers for methane at selected isolated Brønsted sites in zeolites FAU, MFI, BEA, ERI, and CHA are studied by combined quantum-chemicalclassical (QM/MM) calculations in an attempt to understand the factors that determine the reactivity at these Brønsted sites. The barrier of the D/H-exchange reaction for methane was found to corr...

The self- and collective-diffusion behaviors of adsorbed methane, helium, and isobutane in zeolite frameworks LTA, MFI, AFI, and SAS were examined at various concentrations using a range of molecular simulation techniques including Molecular Dynamics (MD), Monte Carlo (MC), Bennett-Chandler (BC), and kinetic Monte Carlo (kMC). This paper has three main results. (1) A novel model for the process...

Nanosized zeolite crystals (nanozeolites) with narrow particlesize distributions and sizes less than 100 nm have received much attention because of their great potential applications in catalysis and adsorption. The decrease in the crystal sizes results in high external surface areas, reduced diffusion path lengths, and more exposed active sites. For example, small Y-type zeolite crystals have ...

Commercial zeolites with CHA, MFI, and LTL framework topology are subjected to acid treatment chromic (H2CrO4) solutions concentrations ranging between 0.1 10 w/%. As forms polymeric species as a function of concentration, specific effects obtained these three zeolites, differing by their topology, pore size, Si/Al ratios crystal size. The etched characterized X-ray diffraction, SEM, TEM, N2 ph...

Fig. 1: Silicalite-1 crystal, top: building scheme with 90° rotated subunits, bottom: picture of the x-z-plane in normal optical mode (transmission). 1. Introduction Adsorption of aromatic hydrocarbons in MFI zeolites has been intensively studied due to the importance of ZSM-5 and the aluminium-deficient analogue, Silicalite-1, in catalysis and separation. Applying different macroscopic techniq...

Zeolites of MFI-type belong to the most important zeolite structures in catalysis and are used in many shape-selective processes in petroleum refining industry, in particular for the kinetic separation of alkane isomers. Practically all important applications involve mixtures. However, due to the experimental difficulty, the number of experimental studies of mixture adsorption and diffusion is ...

The kinetics of alkane cracking in zeolites MFI and FAU have been simulated theoretically from first principles. The apparent rate coefficient for alkane cracking was described as the product of the number of alkane molecules per unit mass of zeolite that are close enough to a Brønsted-acid site to be in the reactant state for the cleavage of a specific C-C bond and the intrinsic rate coefficie...