Catalytic properties of niobium sulphides in the conversion of nitrogen containing molecules

The catalytic properties of niobium sulphides, i.e. NbS(3) and Nb(1.12)S(2) have been examined in the conversion of nitrogen-containing molecules ( n-pentylamine and pyridine), and in the hydrogenation of biphenyl. Compared to MoS(2), NbS(3) and Nb(1.12)S(2) show higher activities for all these reactions and a peculiar ability to perform C-N and C-C bond cleavage. The activities for these last reactions have been related to the acid-base properties of niobium compounds. Moreover, the trisulphide is more active than Nb(1.12)S(2). These differences in activities are discussed in relation to the structural features of both sulphides and the existence in NbS(3) of S(2)(2-) groups and metal-metal pairing.