Catalytic hydrogenation of nitriles over supported mono- and bimetallic catalysts

The bimetallic catalyst systems Pd-Ag/SiO2, Pt-Sn/SiO2, M-Cu/NaY (M = Ru, Rh, Pd, Pt), and M-Ni/NaY (M = Ru, Ph, Pd, Pt) have been tested for the gas phase hydrogenation of acetonitrile and butyronitrile in a fixed-bed microreactor and for the liquid phase hydrogenation of butyronitrile in an autoclave. Addition of M (M = Ru, Ph, Pd, Pt) to Ni promotes the reduction of Ni2+ and significantly increases the hydrogenation rate of butyronitrile in both the gas and the liquid phase. This enhanced activity is indicative of the formation of mixed ensembles on the surface of the bimetallic clusters. Addition of Sn to Pt decreases the activity for acetonitrile hydrogenation and improves the selectivity toward secondary amines. Addition of M (M = Ru, Rh, Pd, Pt) to Cu enhances the reduction of Cu2+ and lowers the activity for acetonitrile hydrogenation. Addition of Ag to Pd lowers the activity for acetonitrile hydrogenation. All M-Cu/NaY catalysts display high selectivity toward the formation of the secondary amine. The interaction between Ru and Ni depends on the Ru precursor; it is stronger with RuCl3 than with RU(NH3)(6)(3+). Addition of ammonia to the reaction mixture lowers the reaction rate, but increases the formation of primary amine. (C) 1999 Academic Press.