Preparation of Co-Mo-γAl 2O 3 and Ni-Mo-γAl 2O 3 catalysts by ph regulation of molybdenum solution. characterization of supported species and hydrogenation activities

Abstract

A new preparation method of the oxidic precursors of Co-Mo-γAl 2O 3, and Ni-Mo-γ Al 2O 3 hydrotreating catalysts has been investigated. The oxo-molybdenum species were added first by an equilibrium adsorption method in a fluidised bed with a pH control of the solution by a regulation process. Different pH were chosen assuming we have different oxo-molybdenum species in solution checked by Laser Raman Spectroscopy (LRS). After subsequent drying and calcination, cobalt or nickel were added by a pore filling method. The oxide precursors have been characterized by X-ray photoelectron Spectroscopy (XPS) and LRS. Then the sulphided catalysts were tested in Hydrogenation of toluene and cyclohexene and the spent sulphided samples have been characterized by XPS. The hydrogenation activities were found to be always more important for Ni-Mo-Al 2O 3 than for Co-Mo-Al 2O 3, catalysts and dependent of the preparation conditions (pH or metal loading). Maximum activities were found for samples impregnated at neutral pH with medium metal loading of the carrier.