Abstract

All important effective ultrasonication variables encountered during carrying out the dehydration of methanol on H-MOR zeolite catalysts to produce dimethylether are studied in the present communication. These variables include; (a) the type of ultrasonication media, (b) the ultrasonication period, and (c) the volume of the ultrasonication liquid media per a given weight of the solid zeolite catalyst. Scanning electron microscope (SEM) photographs of the zeolite have clarified that methanol by itself used as an ultrasonication medium gives the best results concerning the homogeneity of particle sizes compared to the untreated catalyst, where large agglomerates and non-homogeneous clusters appeared. Water used as a sonicated medium showed many large agglomerates in addition to some smaller particles. The d-spacing values obtained from XRD data were plotted as a function of ultrasonication period and volume of methanol per gram of the zeolite in fixed volume of the different alcohols examined. All these data were found to give precise correlation with the catalytic activity of the sonicated H-MOR zeolite. These findings certified that ultrasonication has a deep effect on the unit cell resolution and hence on the catalytic behavior of the dehydration of methanol to dimethyl ether (DME). NH₃-TPD shows that ultrasound irradiation has enhanced the acidity of H-MOR catalyst and hence it is catalytic performance for DME formation.

Key words: Ultrasonication, H-MOR, dimethyl ether (DME), methanol.