Strategies for the synthesis of large zeolite single crystals

The formation of large zeolite single crystals can be achieved by controlling the factors affecting the crystallization process. A review of several major strategies for the synthesis of large zeolite single crystals based on our studies is presented. Through the addition of a nucleation suppresser to the reaction mixture and optimization of the synthesis conditions, pure uniform large single crystals of LTA and FAU (X) are obtained. Large single crystals of MOR, MFI and BET are prepared using the 'two-silicon source' technique. In the presence of fluoride, a large number of single crystals including silicalite-I, B-, Ti-MFI, AlPO₄-5, -11, -34, GaPO₄ and InPO are promoted. It is found that a clear homogeneous solution favors the crystallization of large single crystals of AFI. The alcoholic synthesis route has proved to be one of the most effective ways to obtain large single crystals of some zeolites and metal phosphates.