SELECTIVE DEHYDROGENATION OF ETHANOL TO ACETALDEHYDE OVER SILICALITE-1

Silicalite-1 catalyzes ethanol dehydrogenation to acetaldehyde. On the basis of the IR spectra of ethanol adsorbed on its surface, the active sites are believed to be the active oxygen bridges on which dissociative adsorption of ethanol can take place. The active sites are stable compared with the active oxygen bridges on highly dehydrated silica, which also catalyze the selective ethanol dehydrogenation. Since there were trace amounts of acid site on the Silicalite-1, simultaneous ethanol dehydration was observed. However, almost all the acid sites disappeared by heating at 1070 K in the case of Silicalite-1 containing 0.7 wt% of sodium ions, and ethanol was selectively converted to acetaldehyde. In this treatment, the sodium ions partly poison the active sites for dehydrogenation, but their activity is restored by leaching excess sodium ions from the silicalite-1 under reflux in water. © 1990.