Catalytic Properties of Platinum Nanoclusters Supported on Iron Oxides for the Solvent-Free Hydrogenation of Halonitrobenzene

It is of significance to investigate the support effect in heterogeneous metal catalysts. Pt/Fe₃O₄, Pt/ γ-Fe₂O₃, and Pt/α-Fe₂O₃ nanocomposites with the same Pt nanoclusters were prepared by adsorbing Pt colloidal particles stabilized with simple ions and solvent molecules on different iron oxide supports. The catalytic performances over the as-prepared catalysts for the selective hydrogenation of o-chloronitrobenzene (o-CNB) in the absence of solvent were evaluated. It was found that the catalytic activity and selectivity over the prepared iron oxide-supported Pt nanocluster catalysts were higher than those of a commercial Pt/C catalyst. The selectivity towards o-chloroaniline over Pt/γ-Fe₂O₃ or Pt/α-Fe₂O₃ was higher than that over Pt/Fe₃O₄, while the catalytic activity over Pt/Fe₃O₄ was 50% higher than that over Pt/α-Fe₂O₃. The Pt/iron oxide catalysts also exhibited excellent catalytic properties for the solvent-free selective hydrogenation of other tested halonitrobenzenes, with the selectivity to corresponding haloanilines being > 99%. In addition, the influences of temperature and hydrogen pressure on the solvent-free selective hydrogenation of o-CNB over Pt/Fe₃O₄ were studied. This work is helpful in understanding the superior properties of iron oxide-supported metal nanocluster catalysts and provides a foundation for further developing highly efficient catalytic systems based on metal nanoclusters.