The Preparation of Zeolite Membranes and Coatings

Techniques involved in the preparation of zeolitic films on stable supports can be divided into four categories (1) pre-treatment of the supports, in which the most important is chemical treatment (such as the siloxation of surface-to-anchor zeolite crystallites), (2) synthesis of zeolite film precursors, (3) growth of films on the support surfaces, and (4) elimination of small defects, which can be achieved by chemical vapor deposition (CVD) of silica sources (by reaction with silicon alkoxide or other silylation agents) and other techniques. Processes (2) and (3) are crucial in the preparation of films, 

In the next example (Example 2), a different approach for the preparation of zeolite films will be presented. This method was first proposed by Iler in 1979,11321 and involved the assembly of charged nano-sized particles layer by layer to form multilayer films based on electrostatic interaction, hence called the layer-by-layer (LBL) self-assembly technique. 

Example 2 Applications of LBL self-assembly technique in the preparation of zeolite films.[133] 

Zeolite membranes can also be prepared by the LBL self-assembly technique by using other inert supports, such as gold and carbon, instead of polystyrene beads. This technique for film preparation has several advantages. First, it is the first example of 

Code Molar composition of the starting solution T (°C) Time (t/h) Crystal size (nm) 

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