SUSTAINABLE ZEOLITE BETA FROM FLY ASH: A GREEN PATHWAY TO CATALYTIC MATERIALS

Abstract

Zeolite Beta, a high-silica aluminosilicate with the BEA framework, was successfully synthesized from coal fly ash using an alkali fusion–hydrothermal method assisted by tetraethylammonium hydroxide (TEAOH) as a structure-directing agent. The fusion of fly ash with sodium hydroxide at 550 °C enabled the breakdown of the aluminosilicate glass phase, and subsequent hydrothermal treatment at 150 °C yielded highly crystalline zeolite. X-ray diffraction (XRD) confirmed the formation of the BEA framework with characteristic peaks at 7.6° and 22.5°. Fourier transform infrared (FTIR) spectroscopy revealed asymmetric Si– O–Al stretching, symmetric T–O vibrations, and double-ring features typical of Zeolite Beta. Scanning electron microscopy (SEM) showed irregular intergrown crystallites forming polycrystalline aggregates, while energy-dispersive spectroscopy (EDS) confirmed the dominance of Si, Al, O, and Na, with minor Ca and Fe impurities from fly ash. The study demonstrates that fly ash can be effectively converted into Zeolite Beta, thus coupling industrial waste utilization with the production of high-value catalytic materials.