Research NoteXPS study of a bulk WP hydrodesulfurization catalyst

- The actual active surface of the bulk WP catalyst is a sulfur-containing phase.
- The formation of the tungsten phosphosulfide phase is fast.
- The presence of sulfur decreases the electron densities of the surface WP species.
- Strong adsorption of NH3 (formed by the hydrodenitrogenation of piperidine) on WP.
- NH3 is a strong poison for the metal phosphide hydrodesulfurization catalysts.

The X-ray photoelectron spectroscopy characterization of a bulk WP hydrodesulfurization (HDS) catalyst demonstrated that the actual active surface phase of WP in the HDS of dibenzothiophene (DBT) is a sulfur-containing phase. This tungsten phosphosulfide phase formed faster than the molybdenum phosphosulfide phase, but possessed a lower sulfur content than the corresponding Ni2P and MoP phases. NH3 was the dominant nitrogen-containing species detected in the WP catalyst after simultaneous HDS and hydrodenitrogenation reactions. NH3 decreased the DBT conversion strongly but less than piperidine, indicating that not only N-containing compounds but also NH3 inhibits the HDS activity of WP.

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