Clustering of metal atoms in organic media: V. Production of tailored selectivity in nickel catalysts: Comparisons with Raney nickel

Abstract

Nickel atoms dispersed in weakly complexing solvents (“solvated nickel atoms”) at low temperatures form small metal particles on warmup. These particles can be almost totally amorphous or in the form of small crystallites, depending on the solvent employed. The particles can be tailored to have high catalytic activity or selectivity in hydrogenation and isomerization reactions and to have unusual magnetic properties. Ferromagnetic or nonferromagnetic particles can be prepared, and these particles are effectively stabilized toward sintering by strongly bound organic fragments of the starting solvent. Catalytic activities of the black powders obtained from various solvents have been studied in some detail and indicate: (1) Ni-pentane is an extremely active hydrogenation catalyst for benzene, 1-butene, 1-heptene, and butadiene, more active than Raney Ni; (2) Ni-toluene is also quite active like Ni-pentane, but is selective for hydrogenation of 1,3-butadiene to 1- and 2-butenes before conversion to butane; and (3) Ni-THF is fairly unreactive as a hydrogenation or olefin isomerization catalyst.