Comparison of organic ligand effects on morphology control between disc-like zeolite L crystals and zeolite A and W crystals

Thin disc-like zeolite L crystals were hydrothermally synthesized in the presence of organic ligands, such as catechol and acetylacetone. Thus, zeolite L crystals with many channel entrances on the surface were obtained. Although it was speculated that the complex formation of the organic ligands with aluminate ion in the reaction gels influenced the formation of the disc-like zeolite L crystals, bis-tris which can form a complex with aluminate ion did not show the same effect on zeolite L morphology as catechol and acetylacetone. So, the influence of ligands on crystal morphology was compared between some types of zeolites. Both catechol and bis-tris increased crystal size of zeolite A and zeolite W. Thus, the ligand effect on crystal shapes of disc-like zeolite L was different from that of zeolite A and zeolite W. Moreover, the ligand effect was also examined under agitation. For zeolite L synthesis with the addition of catechol and acetylacetone, the obtained crystalline phase was changed to zeolite T by agitation. Hence, other than the complex formation of aluminate ion with ligands such as catechol, the heterogeneous distribution of reactants probably played an important role in the formation of the disc-like zeolite L crystals.