HZSM-5 and phosphorus-modified ZSM-5 zeolites have been studied by means of in situ IR spectroscopy, temperature- desorption and XPS for adsorption behavior and surface state, by flow method for measuring catalytic activity and selectivity of conversion of ethanol to di-Et ether. On ZSM-5 type zeolites having Broensted acid centers, the mechanism of the formation of di-Et ether may be supposed as follows: ethanol mol. is adsorbed on the hydroxyl group of Al-OH to form adsorbed species which then reacts with another mol. of ethanol in the gas phase to form an adsorbed di-Et ether mol., desorption of the latter from the catalyst surface furnished the final product in free state. The addition of phosphoric acid prevents coke deposit.

Key words: ETHANOL, INFRARED SPECTROPHOTOMETRY, ADSORPTION, MOLECULAR SIEVE, X-RAY PHOTOELECTRON SPECTROMETRY, ZEOLITE ZSM-5, TEMPERATURE PROGRAMMING DESORPTION, SURFACE ANALYSIS, IN-SITU, ETHER