REACTION OF NICKEL TETRACARBONYL WITH GAMMA-ALUMINA

Nickel tetracarbonyl physisorbed from helium carrier onto partially dehydroxylated γ-alumina at 23-50°C rapidly reacts with surface sites to form a yellow complex, probably adsorbed nickel tricarbonyl. Carbon monoxide rapidly reverses this reaction. In flowing helium, the yellow complex loses further carbon monoxide to form a gray species in which CO Ni is about 1.4. Heating to 100°C reduces the ratio to 0.4. The gray species are small clusters of metallic nickel covered with carbon monoxide. Heating to about 450°C liberates additionally about 0.33 molecules of hydrogen, 0.1 of carbon monoxide, and 0.1 of carbon dioxide. This oxidation of nickel(0) by surface hydroxyl groups occurs even in the presence of hydrogen. Heating nickel carbonyl on highly dehydroxylated alumina liberates no hydrogen. © 1979.