Template-free Synthesis for Nano-crystalline Zeolite

In hydrothermal synthesis of zeolites, organic-structure-directing agents (OSDA) are employed to form zeolite structure, in addition to alkali metals, and Si and Al sources. Recently, there has been growing interest in OSDA-free synthesis of zeolites, such as MFI and MOR. Since formation of zeolite nuclei and crystals proceeds in a strong alkaline solution, however, nucleation/crystallization and resolution of zeolites simultaneously occurs, leading to low yield of zeolite and poor crystallinity due to deposition of amorphous silica. In contrast, we successfully prepared MFI and MOR zeolite nanocrystals via hydrothermal synthesis in a water/surfactant/organic solvent, where the non-ionic surfactants adsorbed on the surface of the zeolite precursors likely induced the formation of zeolite nuclei. Moreover, it is considered that the adsorbed surfactant inhibit the zeolite nuclei and crystal from their resolution. Main objective of this study is development of OSDA-free synthesis of MFI zeolite at high zeolite yield.