Conversion of saturated cyclic and noncyclic amines over a sulphided NiMo/Al2O3 catalyst: mechanisms of carbon nitrogen bond cleavage

The objective of this work was to provide comprehensive hypotheses concerning the mechanisms operative in the C-N bond cleavages occurring during the catalytic conversion of amines over a conventional hydrotreating catalyst, so as to account for experimental observations and to help in developing better hydrodenitrogenation catalysts. The approach consists in a study of the relations between the structure and the reactivity of two series of amines with different numbers of hydrogen atoms on the carbon atoms in the alpha and beta positions with respect to their nitrogen atom. It was found that the hydrogen atoms on the carbon atom in the beta position are involved in the formation of hydrocarbons, and that neither the hydrogen atoms on the carbons in the alpha position nor those on the carbon atoms in the beta position are involved in the formation of condensation products. On the basis of these results, two mechanisms are proposed for the formation of the different reaction products.