Chemoselective hydrogenation of halonitroaromatics over γ-Fe2O3-supported platinum nanoparticles: The role of the support on their catalytic activity and selectivity

""Solvated platinum atoms, obtained by metal vapour synthesis (MVS), were conveniently used to prepare γ-iron oxide and γ-alumina supported Pt catalysts containing small metalnanoparticles of controlled size,ranging 0.5 – 3.0 nm in diameter (HRTEM). The γ-Fe2O3-supported Pt system showed higher catalytic activity and selectivity thanthose of a similarly prepared γ-Al2O3-supported system in the selective hydrogenation reactions of p- and o-chloronitrobenzeneto the corresponding haloanilines,in mild reaction conditions (25 °C, 0.1 MPa hydrogen pressure) (p-chloronitrobenzene: Specific Activity (SA) = 59.5 min-1,Selectivity = 99.9%; o-chloronitrobenzene: SA = 42.8 min-1, Sel.99.2%). The Pt\\\/γ-Fe2O3 systemalso showed high catalytic efficiency (Sel. > 98%, at 100% of conversion) inthe selective hydrogenationsof m-chloro-, p- and o-bromo- and p- and o-iodo- nitrobenzenes. XPS structural studies performed on a pristine Pt\\\/γ-Fe2O3sample as well as on a sample recovered after the reaction,indicate that the catalytic process did not induce permanent modification in the chemical and\\\/or electronic structure of the catalyst according with the high reusability of the system.""