Catalytic Dehydration of Ethanol to Ethylene Over Steam-Treated ZSM-5 Zeolites

The steam-treated ZSM-5 zeolites are characterized by XRD, N-2 sorption, SEM, Al-27 MAS NMR and NH3-TPD techniques. The steaming procedures do not alter textural structures, but generate significant variations in the acidity. The catalytic properties of steam-treated ZSM-5 catalysts in dehydration of ethanol into ethylene are investigated in a fixed bed reactor at 150-350 degrees C and an atmospheric pressure. The decreased total acid sites and increased ratio of weak acid to strong acid after steam treatment may suppress ethylene from secondary reactions, and therefore lead to improved ethylene selectivity at higher temperature. Compared to parent ZSM-5, ZSM-5 treated at 600 degrees C (ZSM-600) shows excellent stability for ethylene production. The reaction conditions (space velocity and ethanol partial pressure) have significant influences on ethanol conversion and ethylene selectivity.