PRELIMINARY STUDIES ON THE SYNTHESIS OF ALKALINE-FREE LARGE CRYSTALS OF ZSM-5

Single crystals of ZSM-5 were synthesized in three systems containing Na** plus - TPA, Li** plus - TPA, and NH** plus //4 - TPA, respectively. Applying a reaction mixture of the molar composition 8 TPA plus 123 (NH//4)//2O plus Al//2O//3 plus 59 SiO//2 plus 2280 H//2O, alkaline-free, homogeneous, and pure single crystals of ZSM-5 were prepared up to a length of 350 mu m. The crystal size and yield were found to be dependent on the water content of the starting reaction mixture and on the type of aluminium source; for example, boehmite and aluminium-triisopropylate.