STUDIES ON THE SYNTHESIS OF ZEOLITE ZSM-5 WITH DIFFERENT MORPHOLOGY AND CRYSTAL SIZE

Factors affecting the hydrothermal crystallization of zeolite ZSM 5 such as n (SiO 2)/ n (Al 2O 3), crystallization temperature, alkalinity, oxyanion, seeding and aging, from K 2O Al 2O 3 SiO 2 TPABr(tetrapropyl ammonium bromide) H 2O aluminosilicate gels were studied The high crystalline ZSM 5 zeolites of larger size were obtained from these gels, and their crystal morphology tended to transform from spherulite to euhedralite and grew larger when increasing either Al 2O 3 content or crystallization temperature or replacing KOH by less alkaline K 2CO 3 Oxyanion such as NO - 3 played a role to some extent in preventing the formation of euhedralite in richer alumina recipe Compared with seeding, a combination of aging and crystallization was more facile in tailoring of crystal size from 1 0 to 40 μm It was shown by IR that the aged gel did not have the structural characteristics of ZSM 5 crystallite In addition, the observation that no XRD peak broadening of (002) diffraction was observed as compared with standard sample α SiO 2 revealed the absence of tiny crystals (less than 0 5 μm) in as synthesized zeolite samples