EXAFS STUDY IN-SITU OF THE REDUCIBILITY O F A SILICA-SUPPORTED COBALTFISCHER-TROPSCH CATALYST

The reduction under hydrogen flow of a 25% Co/SiO2 catalyst for the hy drocarbons synthesis have been followed in situ by Extended X-Ray Adso rption Fine Structure Spectroscopy (EXAFS). The analysis of the EXAFS spectra enables the identification of a Co3O4 spinel phase before trea tment. The two step reduction of Co3O4 to CoO then Co degrees, as obse rved by EXAFS, is consistent with the studies in XPS (surface) and TPR (bulk). The coordination number of cobalt has been determined at each reduction step.