Hydrogenolysis of alcohols: III. Effect of supports on reduced nickel oxide for the conversion of alcohols to ethers

Abstract

Catalysts prepared from nickel oxide deposited on kieselguhr, silica, silicaalumina, and alumina were reduced and studied for the conversion of primary alcohols. The alcohols studied were n-propanol, n-butanol, 2-methylbutanol, and 2,2-dimethylbutanol (neopentyl alcohol). The exepriments were made in a pulse reactor in the presence of a flow of hydrogen, at atmospheric pressure and at about 190 °. Three main reactions occur in the presence of a nickel-kieselguhr catalyst: (1) reductive dehydroxymethylation, (2) reductive dehydroxylation, and (3) ether formation. The last two reactions are related to the intrinsic acidic sites of the catalyst. Nickel-kieselguhr catalyst containing 6–10% of nickel gave in the case of n-butanol 73% conversion, with 72 mole % of di- n-butyl ether in the product. The presence of Na + in the catalyst inhibits the formation of ethers, while the dehydroxymethylation reaction increases. A continuous flow reaction at 190 ° demonstrated that nickel-kieselguhr catalyst containing 6% of nickel shows no deterioration after 16 hr of use. At 170 °, with a hydrogen to alcohol ratio of 10 and LHSV of 2, n-butanol reacted to the extent of 89%, with 91% yield of di- n-butyl ether.