Comparative vapor phase synthesis of ETBE from ethanol and isobutene over different acid zeolites

Vapor phase synthesis of ETBE from ethanol and isobutene has been investiga ted over US-Y, Beta, and ZSM-5 zeolites with different Si/Al ratios, using Amberlyst-15 as a reference catalyst. The zeolites were characterized by X- ray diffraction and nitrogen adsorption-desorption isotherms at 77 K. Total acidity of the Beta zeolites was determined by ammonia-TPD measurements wh ereas IR spectroscopy was used to investigate the OH stretching region and evaluate the Bronsted and Lewis acid contents by pyridine adsorption. Beta zeolites, with higher external surface area, were more active than the othe r zeolites. The highest yields of ETBE were obtained for Beta samples with high Bronsted acid content and low SiOH/AIOHSi ratio. (C) 2001 Academic Pre ss.