A facile synthesis of ZSM-11 zeolite particles using rice husk ash as silica source

Abstract

ZSM-11 zeolite particles were prepared through in-situ extraction (extraction and conversion in a single step process) of silica from rice husk ash in the presence of other aqueous-based precursors (sodium aluminate and tetrabutyl ammonium hydroxide) following a simple hydrothermal condition at 100°C. The particles were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA) and field emission scanning electron microscopy (FESEM). XRD pattern confirmed the crystallization of ZSM-11 obtained at 100°C/12 days. The vibration bands at around 548 and 1221cm−1 indicated the presence of double 5-ring (D5R) in the pentasil zeolite structure of ZSM-11. The exothermic peak at 463°C in DTA curve indicated the removal of tetrabutyl ammonium ion (TBA+) which was used as a structure directing agent (SDA). FESEM image showed that nano-sized ZSM-11 particles were agglomerated in the crystals. The Si/Al ratio of ZSM-11 particles was found to be 51 as indicated by the elemental analysis with energy dispersive X-ray (EDX).