Enhancement of the hydrodesulfurization and C−S bond cleavage activities of rhodium phosphide catalysts by platinum addition

To enhance the hydrodesulfurization (HDS) activity of SiO2-supported Rh phosphide catalysts, various second metal-added Rh–P catalysts were developed; furthermore, the effect of the addition of the second metal on the HDS performance was examined. The second metals (M: Ru, Pt, and Ir) were selected as per the Sabatier principle. In situ X-ray diffraction revealed the formation of an Rh2P phase in the Rh–M–P catalyst after reduction. The addition of Ru and Pt to the Rh–P catalyst enhanced the C−S bond cleavage activity, whereas the addition of Ir had virtually no effect. The Rh–Pt–P catalyst demonstrated the highest HDS activity among Rh–M–P catalysts. The characterization results revealed the presence of positively charged Pt on the Rh–Pt–P catalyst surface, in which Pt and Rh cooperatively act as active sites to enhance the C−S bond cleavage activity.