Growth of larger crystals of ZSM-5 in the system 4(TPA) 2O-38(NH 4) 2O-x(Li,Na,K) 2 O-A1 2O 3-59SiO 2-750H 2O

Abstract

The synthesis of zeolite TPA-ZSM-5 with (NH 4) 2O/Al 2O 3 = 38 and different amounts of Li 2O, Na 2O or K 2O was studied. Kinetic crystallization data and the growth of the crystals as a function of time are reported. The results show an increment of the size of the crystals when alkali metal oxide is added to the system. With Li 2O, unusually uniform, large, lathshaped crystals of ZSM-5 ∼ 140 ± 10 μm in length were obtained. The time of nucleation is long when only (NH 4) 2O is used with TPA and decreases when alkali metal oxide is added to the system.