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 investigated 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 whereas IR spectroscopy was used to investigate the OH stretching region and evaluate the Brønsted and Lewis acid contents by pyridine adsorption. Beta zeolites, with higher external surface area, were more active than the other zeolites. The highest yields of ETBE were obtained for Beta samples with high Brønsted acid content and low SiOH/AlOHSi ratio.