Understanding the Hydrodenitrogenation of Heteroaromatics on a Molecular Level

The cleavage of recalcitrant C-N linkages in heteroaromatic molecules is a critical component of hydrodenitrogenation (HDN) reactions, the processes by which N atoms are removed from crude fuels. C-N bond cleavage of heteroaromatics with traditional HDN catalysts such as sulfided Ni/Mo-Al₂O₃ and Ni/W-Al₂O₃ requires aggressive conditions to hydrogenate the heterocyclic rings and often unnecessarily saturates the carbocyclic rings as part of the C-N cleavage process. In contrast, small-molecule models have illustrated selective hydrogenation of the heterocyclic ring, providing mechanistic insight into HDN processes and inspiring the design of new, more selective HDN catalysts.