Hydrothermal synthesis of nanosized ZSM-22 and their use in the catalytic conversion of methanol

Abstract

ZSM-22 zeolite with different crystal lengths was prepared using a modified hydrothermal method. Rotation speed, Si/Al molar ratio and co-solvent have important effects on the crystal size of ZSM-22. The nanosized zeolite samples were characterized by X-ray diffraction, X-ray fluorescence, nitrogen adsorption, scanning electron microscopy, temperature-programmed desorption of ammonia and solid state nuclear magnetic resonance. The catalytic performance of nanosized ZSM-22 was tested using the conversion of methanol. Compared to conventional ZSM-22, the nanosized ZSM-22 zeolite exhibited superior selectivity to ethylene and aromatics and lower selectivity to propylene. Stability against deactivation was clearly shown by the nanosized ZSM-22 zeolite. A higher external surface area and smaller particle size make this nanosized ZSM-22 zeolite attractive for catalytic applications.