The synthesis and catalytic properties of hydrogenation catalysts of the RaneyR type derived from aluminum-nickel and aluminum-molybdenum-nickel RSR alloy powders have been evaluated. Two binary aluminum-nickel alloys, RSR 588, with 50 w/o Ni corresponding to currently available RaneyR commercial alloys, and RSR 587, with 28.5 w/o Ni corresponding to the proeutectic composition which produces exclusively Al3Ni as the precursor phase, were synthesized. One ternary, RSR 589, aluminum-molybdenum-nickel alloy with a nickel and molybdenum content to correspond to a commercial promoted RaneyR alloy was prepared.
The hydrogenation catalytic activity for six organic compounds representing diverse functionalities was measured in a bench scale batch liquid slurry catalytic reaction. Each catalyst was suspended in an agitated solution of the reaction (0.8 to 5M) at 22°C under a constant hydrogen over pressure of 0.86 atmospheres. A declining pressure technique was also used as a measure of catalytic activity where the catalyst was suspended in an agitated solution of the three reactants at 80°C at an initial hydrogen pressure of four atmospheres. The reactants selected consisted of acetone, nitrobenzene, itaconic acid, butyronitrile, toluene, and dextrose. The organic functionalities hydrogenated consisted of the conversion of:
(1) Carbonyl to alcohol
(2) Nitro group to amine group
(3) Double carbon bond to a single carbon bond
(4) Nitrile group to an amine group
(5) Aromatic to a hydroaromatic ring
(6) Aldehyde to an alcohol.
RSR 587 catalyst, containing 28.5 w/o nickel, provides superior hydrogenation rates over bulk cast RaneyR nickel catalysts by factors ranging from 2 to 20 for selected reactions. Rapid solidification followed by heat treatmen0t at 850°C of Al ∼42 w/o Ni powders yielded the greatest specific catalytic activity and provides a unique enrichment path for the formation of the peritectic phase, A13Ni, and subsequently the most active skeletal nickel pore structure with the least amount of waste aluminum.