Catalytic hydrogenation of sulfur-containing nitrobenzene over Pd/C catalysts: In situ sulfidation of Pd/C for the preparation of PdxSy catalysts

• Pd/C was in situ sulfided to PdxSy/C during hydrogenation of 4-nitrothioanisole.
• The sulfidation was highly dependent on temperature.
• The sulfided Pd/C exhibited high stability.

The preparation of supported palladium sulfides catalysts has attracted much attention due to their good sulfur-resistant properties in the hydrogenation of sulfur-containing compounds. In this work, we unambiguously demonstrated that Pd/C catalyst could be in situ sulfided by organic sulfur-containing reactant molecules and the sulfidation was highly dependent on temperature. The in situ sulfidation of Pd/C catalyst was composed of a reaction of Pd with the sulfur derived from the cleavage of CS bond of sulfur-containing reactant molecules, followed by a transformation to PdxSy at high temperatures (around 120 °C). The sulfided Pd/C catalyst could be used for at least 18 recycles without a significant loss in its activity during the hydrogenation of sulfur-containing nitrobenzene at 180 °C with 3 MPa H2, which could be attributed to the stable presence of Pd4S and Pd16S7.

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