Zeolites

Abstract

The article contains sections titled: 1. Introduction 2. Nomenclature 3. History 4. Structure, Composition, and Properties 4.1. Framework Structure 4.2. Nonframework Cations 4.3. Chemical and Physical Properties 4.3.1. Physical Properties 4.3.2. Chemical Properties 5. Characterization 6. Occurrence, Mining, and Processing of Natural Zeolites 7. Production of Synthetic Zeolites 7.1. Chemistry of Zeolite Synthesis 7.2. Composition of Reaction Mixtures 7.3. Raw Materials 7.3.1. Synthesis Conditions 7.3.2. Examples of Industrial Zeolite Syntheses 7.3.3. Post Synthesis Treatments 7.3.4. Environmental Aspects 8. Commercial Applications and Importance 8.1. Natural Zeolites 8.2. Synthetic Zeolites 8.2.1. Adsorption 8.2.2. Membranes 8.2.3. Catalysis 8.2.4. Other Uses 9. Toxicology Zeolites are hydrated aluminosilicates with a three‐dimensional framework structure constructed of SiO 4 and AlO 4 tetrahedra linked through oxygen atoms. They contain regular channels or interlinked voids whose aperture diameters are in the micropore range. The regular nature of the channels and apertures, whose dimensions are of the same order of magnitude as molecular diameters, enables the zeolites to function as molecular sieves and gives them value as selective adsorbents for separating substances and as shape‐selective catalysts. This article gives an overview of history, structure, properties, occurrence, production, and applications of zeolites.

Amino-Acid Adsorption in MFI-Type Zeolites Enabled by the pH-Dependent Ability to Displace Water

“…This results in the chemical formula given by H 7 [Al 7 Si 89 O 192 ] per unit cell. The framework is built by interconnected five rings, which form a 3D ten-ring pore structure , with an effective pore size of 5.4 × 5.6 Å . For a given pH in the adsorption experiments, MFI-27 was equilibrated prior to use.…”

Atomic Layer Deposition in a Metal–Organic Framework: Synthesis, Characterization, and Performance of a Solid Acid

“…Aluminum oxides and aluminates are ubiquitous in catalysis, both as supports and as active species themselves. − Aluminum-based acid catalysts such as aluminas, zeolites, − and aluminates in general are especially noteworthy due to their remarkable and well-studied properties …”

Electrosynthesis of dimethyl carbonate from methanol and CO2 using potassium methoxide and the ionic liquid [bmim][Br] in a filter‐press cell: a study of the influence of cell configuration

“…Molecular sieves were also tested as dehydrating agents to trap the water being formed and shift the equilibrium to higher production of DMC (CH 3 OH + CO 2 →DMC + H 2 O). Molecular sieves are crystalline aluminosilicates with a three‐dimensional framework structure of SiO 4 and AlO 4 distributed in tetrahedral chains linked through oxygen atoms . They have a very narrow distribution of micropores and only components with critical diameter smaller than the opening of the micropores will be adsorbed .…”