Chapter 19 - Strategies Towards the Assembly of Preformed Zeolite Crystals into Supported Layers

Abstract

This chapter reviews the methods used for the assembly of preformed zeolite crystals onto various supported layers. The progress in this area is a result of the tremendous development of the synthesis of zeolite materials in nonconventional forms. Zeolite crystallization is a complex process depending on many parameters such as temperature, pH, composition of the reaction mixture, nature of reactants, and pre-treatment. Typically, synthetic zeolites are produced as a crystalline powder of micron-sized crystallites by hydrothermal treatment of synthesis gels or solutions. Another disadvantage of zeolite powders is that they are difficult to handle, causing loss of material during process set-up or zeolite regeneration. One possibility to optimize the technological use of zeolites is by the formation of zeolite macro particles such as extrudates, tablets, and spheres, meeting the process requirements for activity, pressure drop, and attrition resistance. The methods for the assembly of performed zeolite crystals considered in this chapter are simple and do not involve any substrate modification (other than cleaning) or chemical modification of the zeolite crystals. Considering the progress made in manipulating the zeolite morphology, improvements of the assembly method are highly desirable. Such improvements could lead to the deposition of dense layers of preformed zeolite crystals with tailored zeolite channel orientation in respect of the support and film thickness, both achieved by manipulation of the zeolite crystal morphology.