Co-K and Mo-K edges Quick-XAS study of the sulphidation properties of Mo/Al2O3 and CoMo/Al2O3 catalysts

The sulphidation process of two catalysts (Mo/Al2O3 and CoMo/Al2O3) has been investigated by time-resolved X-ray Absorption Spectroscopy. With the unique edge jumping capability available at the SOLEIL synchrotron, studies of cobalt and molybdenum species have been conducted simultaneously on the same bimetallic catalyst. A methodology combining Principal Component Analysis and Multivariate Curve Resolution with Alternating Least Squares methods unravels a 3-stepped or 4-stepped sulphidation process for the bimetallic and monometallic catalysts, respectively. An oxysulphide-based molybdenum species has been identified as an intermediate for Mo/Al2O3 and a MoS3-like species has been observed for both catalysts.