Reactions of alcohols: V. Conversion of alcohols to ethers over nickel and other transition metal catalysts in the presence of hydrogen

Abstract

The reactions of primary alkanols have been investigated over reduced nickel oxide and other transition metal oxides and metals in the presence of a flow of hydrogen in a micropulse reactor. The temperature of reduction of nickel oxide greatly affects its catalytic activity and selectivity for the conversion of n-butanol to dibutyl ether. After 20 hr of reduction at 190 ° or after 1 hr of reduction at 300 ° the catalyst shows 50% reactivity and 90% selectivity for the conversion of butanol to dibutyl ether. The ether forming properties of the reduced nickel oxide were correlated with the intrinsic acidic sites of the catalyst. Both the activity and selectivity of the catalyst are impaired by the presence of pyridine. The selectivity of the nickel catalyst towards ether formation is also influenced by the amounts of butanol injected. An injection of at least 2–6 μl of butanol per 200 mg of catalyst is required for 80% selectivity for dibutyl ether formation. Of the transition metal catalysts, Ni, Ir, and Pd show good properties for the conversion of alcohols to ethers. Rh and Ru, under similar conditions act as dehydration and dehydrogenation catalysts, while cobalt acts only as a dehydrogenation catalyst.