The selectivity of nitrile hydrogenation to prim. sec. and tert. amines is dominantly controlled by the transition metal, similar selectivities are observed in gas phase flow and liquid phase batch runs. All amines are formed during one residence at the catalyst surface. Istopic labeling in acetonitrile hydrogenation and co-hydrogenationof acetonitrile and butyronitrile show that the hydrogen atoms in the amine groups of the product are not provided by H_(ads) at the metal surface, but by the methyl group of other acetonitrile molecules. It is concluded that N-bonded surface complexes are likely intermediates for the formation of prij. sec. adn tert. amines.
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