Dexterous template-free synthesis of ferrisilicate with MFI morphology using rice husk ash

Abstract Sodium silicate, the supernatant solution extracted from rice husk ash was used as silica source in hydrothermal synthesis of Fe ZSM-5 zeolites by an organic-free method. Characterization techniques such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), BET, X-Ray Fluorescence (XRF), Diffuse Reflectance Spectroscopy — Ultra Violet (DRS-UV) and Temperature-Programmed Desorption-ammonia (NH 3 -TPD) unambiguously confirm the formation of Fe ZSM-5. Phosphoric acid used in the synthesis, forms an oxo-anion complex with iron and this complex acts as surface directing agent in the formation of Fe ZSM-5 zeolites. Characterization results prove that rice husk ash can successfully be recycled as ferrisilicates with MFI morphology even in the absence of template.