Molecular Modeling of the Synthesis of Zeolites and Related Nanoporous Materials
type: CreativeWork
description: Zeolites are microporous inorganic crystals with a framework that mainly contains silicon, oxygen and aluminum. The chemical composition is comparable to quartz, but the crystal structure is fundamentally different. Zeolites contain regular cavities (channels and cages) with a maximum diameter of 1.2 nanometer, large enough to contain small organic molecules. The walls of the cavities represent a huge internal surface (of the order of 1000 m2/g). Due to the well-defined shape of these channels and cages, only the molecules with a compatible structure can enter the internal cavities of a zeolite. This principle is called shape selectivity and it enables the separation of chemically similar but structurally different molecules. A Si/Al substitution in the framework introduces a catalytically active site on the walls of the zeolite cavities. During the past 60 years, all these specific properties have driven the development of new zeolites and the implementation of zeolites in industrial applications. The world-wide production of zeolites amounts to 4.2 million tons per annum, with applications in diverse markets such as petrochemistry, agriculture, animal husbandry, pharmacy, and so on. The most important applications in the western world include catalytic cracking in the petrochemical industry, ion exchange (softening and purification of water), and the separation and extraction of gases and solvents. A recent development in this field is the search for micro- and mesoporous materials. The IUPAC defines a microchannel as a pore with a diameter ranging from 0.25 nm to 2 nm, while a mesopore has a diameter between 2 nm and 50 nm. The limited diffusion rate of guest molecules in the micropores of a conventional zeolite is a well-known obstacle for the transport of reagents and reaction products. Another issue is the formation of side-products that reduce the diffusion rates and block the access to catalytically active sites. The regeneration of a zeolite catalyst, in wh…
abstract: Zeolites are microporous inorganic crystals with a framework that mainly contains silicon, oxygen and aluminum. The chemical composition is comparable to quartz, but the crystal structure is fundamentally different. Zeolites contain regular cavities (channels and cages) with a maximum diameter of 1.2 nanometer, large enough to contain small organic molecules. The walls of the cavities represent a huge internal surface (of the order of 1000 m2/g). Due to the well-defined shape of these channels and cages, only the molecules with a compatible structure can enter the internal cavities of a zeolite. This principle is called shape selectivity and it enables the separation of chemically similar but structurally different molecules. A Si/Al substitution in the framework introduces a catalytically active site on the walls of the zeolite cavities. During the past 60 years, all these specific properties have driven the development of new zeolites and the implementation of zeolites in industrial applications. The world-wide production of zeolites amounts to 4.2 million tons per annum, with applications in diverse markets such as petrochemistry, agriculture, animal husbandry, pharmacy, and so on. The most important applications in the western world include catalytic cracking in the petrochemical industry, ion exchange (softening and purification of water), and the separation and extraction of gases and solvents. A recent development in this field is the search for micro- and mesoporous materials. The IUPAC defines a microchannel as a pore with a diameter ranging from 0.25 nm to 2 nm, while a mesopore has a diameter between 2 nm and 50 nm. The limited diffusion rate of guest molecules in the micropores of a conventional zeolite is a well-known obstacle for the transport of reagents and reaction products. Another issue is the formation of side-products that reduce the diffusion rates and block the access to catalytically active sites. The regeneration of a zeolite catalyst, in wh…
author: Verstraelen, Toon
language: eng
keywords: Chemistry
date published: 2009
date modified: 2026-07-24T02:22:52Z
provider: Ghent University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Ghent University

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property ID: Handle
value: http://hdl.handle.net/1854/LU-677098