Recent legislation directed at reducing nitrogen levels in fossil fuels has
led to numerous studies of the hydrodenitrogenation (HDN) process, whereby
nitrogen is removed from organic compounds in petroleum feedstocks. In thi
s review a comprehensive study of the coordination, activation, hydrogenati
on, hydrogenolysis and denitrogenation of N-heterocycles assisted by transi
tion metal complexes in either fluid solution or single-site systems, is re
ported. Furthermore, similarities to the reactions occurring in the HDN pro
cess over commercial heterogeneous catalysts are also discussed.