A Review of the Structural Properties and Applications of Zeolites

Abstract

The industry of zeolite synthesis has developed over the last decade, with an extensive usage in many industrial processes due to their resistance to chemical and thermal operating conditions. Basic reactants and templates are used as starting components for synthesising zeolites. In the basic reactants, an aluminium source, a silicon source, and water are generally used as the reactants for the synthesis process. In this process, as mentioned earlier, the zeolite framework depends mainly on the silica and alumina in building the primary units of the structure, while the water acts as the solvent during the synthesis process. Generally, water is used in these processes because it is capable of dissolving most of the ionic compounds that are used at the conditions of the process. The low viscosity of water makes it a good medium in which the reaction can take place, resulting in metastable phases with considerable crystal growth and various shapes. However, some compounds are insoluble in water, even at supercritical conditions. Therefore, mineralizers, such as sodium carbonate, sodium borate, and sodium sulphide, are added to enhance the solubility of the solute. This review article presents the structure, properties, and synthesis methods of zeolites , including in-situ synthesis, and secondary growth method. The advantages as well as the limitations of these synthesis methods are indicated. Also, a short overview of today’s state of the art of zeolite membranes applications is summarized and compared, as they are widely used in many technical and commercially relevant separation processes. The experimental work and results obtained from using zeolite NaY for ethanol dehydration were above 5000 indicating the great potential of these material in the separation processes.