Hydrogenation of p-Chloronitrobenzene on Au Nano-Clusters: Effects of Support

Gold nanocluster has been reported to have high activity and selectivity for various liquid phase hydrogenation reactions. In this study, gold clusters were loaded on various supports, i.e., TiO₂, ZnO, Fe₂O₃, ZrO₂, and CeO₂. The Au-cluster catalysts were prepared by deposition-precipitation method using HAuCl4 as the precursor. These catalysts were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic properties of these catalysts were studied in a batch slurry reactor for hydrogenation of p-chloronitrobenzene (p-CNB) at 1.1 MPa H₂ pressure, 373 K and 300 rpm. The activity decreased in the following order: Au/TiO₂ ≧ Au/ZnO ≧ Au/CeO₂ (Nikki) ≧ Au/CeO₂ (Evonik) ≧ Au/Fe₂O₃ ≧ Au/ZrO₂. TiO₂-supported Au clusters had a higher activity than others, due to its hydrophilicity.