ETHANOL CONVERSION OVER ION-EXCHANGED ZSM-5 ZEOLITES

The activities of ZSM-5 zeolites ion exchanged with proton and CuII for ethanol conversion were observed using an ordinary flow reaction in order to explore the role of the proton and the transition metal ion in the conversion of ethanol under an atmosphere with and without oxygen. Proton-exchanged ZSM-5 favoured the dehydration of ethanol to form ethene, irrespective of the presence or absence of oxygen. On the other hand, the transition metal ion in the ZSM-5 promoted the deep oxidation of ethanol to form a deep oxidation product (carbon dioxide + carbon monoxide) under the reaction conditions used. Increasing the concentration of the surface hydroxyl groups of the H-NaZSM-5 catalysts caused an increase in dehydration activity and a decrease in the activity for oxidation. Increased CuII ion-exchange in CuII-NaZSM-5 increased the activity for oxidation of ethanol. Various intermediates were observed in the situ Fourier transform IR spectra of ethanol adsorbed on HZSM-5, and CuII-NaZSM-5. Reaction schemes for the dehydration of ethanol to ethene over HZSM-5 and the oxidation of ethanol over CuII-NaZSM-5 are suggested. © 1990.