Preparation of Highly Dispersed Pentlandites (M,M‘)₉S₈ (M, M‘ = Fe, Co, Ni) and Their Catalytic Properties in Hydrodesulfurization

A series of highly dispersed single phase pentlandites (Co 9 S 8, NiCo 8 S 8, FeCo 8 S 8, Ni 3 Co 6 S 8, Ni 4.5 Fe 4.5 S 8 ) was prepared by coprecipitation followed by sulfidation and reducing treatment at 300 °C. These mixed sulfides consist of crystalline particles with homogeneous distribution of the elements as shown by high-resolution microscopy and EDX analysis. The distribution of the cations in tetrahedral and octahedral sites of the pentlandite structure was characterized by EXAFS and Mössbauer spectroscopy. The catalytic activity of the sulfides in the model thiophene hydrodesulfurization reaction increases in the following order: Ni 4.5 Fe 4.5 S 8 ≪ FeCo 8 S 8 < Co 9 S 8 < NiCo 8 S 8 < Ni 3 Co 6 S 8 . Activity−properties correlations are discussed, on the basis of extended Hückel electronic structure calculations and temperature programmed reduction measurements.