Hydrous zirconia supported iridium nanoparticles: An excellent catalyst for the hydrogenation of haloaromatic nitro compounds

Ir/ZrO2 center dot xH(2)O was prepared by co-precipitation and characterized by TEM, XRD, and XPS. It showed an excellent catalytic performance for the hydrogenation of haloaromatic nitro compounds to the corresponding amines in the mixture solvent of ethanol and water. The catalyst gave both conversion and selectivity to be over 99.9% for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. Besides the intrinsic characterization of iridium in the hydrogenation of haloaromatic nitro compounds, the high activity and selectivity of Ir/ZrO2 center dot xH(2)O is probably attributed to the formation of hydrogen bond between substrate and the hydroxyl groups on the surface of the hydrous catalyst or solvent water to activate the N=O bond in nitro group. The activated N=O bond is easy to be attacked by the activated hydrogen, so the hydrogenation is promoted. (C) 2009 Elsevier B.V. All rights reserved.