The effects of seeding in the synthesis of zeolite ZSM-48 in the presence of tetramethylammonium ion

The hydrothermal synthesis of ZSM-48 has been investigated using tetramethylammonium (TMA) ion with and without addition of ZSM-48 seeds. Without addition of seed crystals, main product was ZSM-39. Only cristobalite was formed without addition of TMA in the seeded system. Hence, addition of both seeds and TMA ions is essential to obtain the well-crystallized ZSM-48 samples The morphology of resultant ZSM-48 crystals in the seeded system was hexagonal rod. It was suggested that the ZSM-48 seeds would accelerate the crystallization of ZSM-48 zeolite and avoid the formation of ZPA-39. TMA might assist the growing process of ZSM-48 over seed crystals and stabilize the ZSM-48 structure. (C) 2004 Elsevier Inc. All rights reserved.