Structural Change of Supported Ni-Mo Sulfide Catalysts During the Hydrogenation of Coal-Derived Liquid

N. Matsubayashi, H. Shimada, T. Sato, Y. Yoshimura, M. Imamura, and A. Nishijima
[Fuel Process. Technol., Vol.41, pp.261-271, 1995]

The different structures of Ni-Mo/Al₂O₃ catalysis used in the secondary hydrogenation of coal-derived liquids were analyzed by the X-ray absorption fine structure (XAFS) method to clarify the catalysis deactivation mechanisms during the hydroprocessing. The XAFS analyses revealed the agglomeration of MoS₂ crystallities, as well as the decomposition of the catalytically active 'Ni-Mo-S' structure in the sampled catalysts. A greater amount of agglomeration was observed in the catalyst taken from the reactor exit of the reactor presumably caused the enhanced agglomeration of the MoS₂ crystallities. On the other hand, the changes observed in the local structure around Mo and Ni due to the decomposition of the Ni-Mo-S structure were pronounced in the catalyst sampled at the most probable cause of the decomposition.