Synthesis, characterization and evaluations of micro/mesoporous ZSM-5 zeolite using starch as bio template

Abstract

We report a simple and economical method to synthesis hierarchical ZSM-5 zeolite using a natural polymer, soluble starch, as a mesotemplate. The synthesized samples were characterized with X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, nitrogen sorption, ammonia temperature-programmed desorption and thermogravimetric analysis. The crystallinity and Mordenite Framework Inverted structure of the samples was confirmed by X-ray diffraction and Fourier transform infrared spectroscopy analysis. Scanning electron microscopy and transmission electron microscopy images revealed the presence of mesopores in the synthesized samples. The nitrogen adsorption/desorption results of the hierarchical samples have been found to be in agreement with the scanning electron microscopy and transmission electron microscopy results and support the development of mesoporosity. The acidity of the hierarchical zeolite was studied using ammonia temperature-programmed desorption. The thermogravimetric analysis confirmed the thermal stability of the synthesized samples up to 750 °C. The catalytic activities of the modified and unmodified zeolites were specifically tested for the esterification of acetic acid with benzyl alcohol. The results indicate that the hierarchical ZSM-5 catalyst offers a better catalytic yield (76%) than the unmodified systems.