Reactions of secondary saturated alcohols over reduced nickel oxideCab-O-Sil catalysts in the presence of hydrogen variables affecting ether formation

Abstract

Dehydration of secondary alcohols in the gas phase over nickel catalysts was investigated by passing the gaseous mixture of the alcohol and hydrogen over a catalyst of reduced NiO on CabOSil in the temperature range 160–190 °C. The reactivity of secondary alcohols towards ether formation is appreciably less than that of primary alcohols at similar conditions. The activity of the catalyst which depends on the percentage of nickel and on its reduction temperature is appreciably reduced by small additions of sodium ion to the catalyst and by small amounts of water in the gas stream. The structure of the alcohol influences the extent of ether formation. It decreases as the alcohol becomes more bulky. It seems that the polarity of the alcohol, as indicated by Taft's correlation, also participates in determining the extent of ether formation. These results are consistent with the interpretation that the activity of reduced nickel oxide as a catalyst for dehydration of alcohols is due to its intrinsic acidity and probably also to its intrinsic basicity.