Excellent catalytic properties over nanocomposite catalysts for selective hydrogenation of halonitrobenzenes

A partially reduced Pt/ γ-Fe 2O 3 magnetic nanocomposite catalyst (Pt/ γ-Fe 2O 3-PR) exhibited excellent catalytic properties in the selective hydrogenation of 2 , 4 -dinitrochlorobenzene and iodonitrobenzenes. The selectivity to 4-chloro- m-phenylenediamine (4-CPDA), meta-iodoaniline ( m-IAN), and para-iodoaniline ( p-IAN) reached 99.9%, 99.8%, and 99.4%, respectively, at complete conversion of the substrates. The hydrodehalogenation of 4-CPDA and IANs was fully suppressed for the first time over Pt/ γ-Fe 2O 3-PR. It was found that CO chemisorption on the Pt nanoparticles deposited on the partially reduced γ-Fe 2O 3 and Fe 3O 4 nanoparticles was very weak, implying a weak tendency of the electronic back-donation from the Pt nanoparticles to the π ∗ antibonding orbitals of the adsorbed molecules. We believe that this is a cause of the superior selectivity to the haloanilines in the hydrogenation reactions of interest over the Pt/ γ-Fe 2O 3-PR catalyst.