Liquid Phase Hydrogenation of Nitrobenzene to Para-Aminophenol over Pt/ZrO2 Catalyst and SO4 2-/ZrO2-Al2O3 Solid Acid

ZrO2-Al2O3 binary oxide was prepared by homogeneous coprecipitation method. SO4 (2-)/ZrO2 and SO4 (2-)/ZrO2-Al2O3 were prepared by impregnation method and were characterized by BET, XRD and TPD. Pt/ZrO2 was prepared by incipient wetness impregnation of ZrO2 with an aqueous solution of H2PtCl6. Subsequently, hydrogenation of nitrobenzene to para-aminophenol over Pt/ZrO2 catalyst and SO4 (2-)/ZrO2-Al2O3 solid acid using water as solvent was performed. The results indicate that para-aminophenol as well as a small quantity of aniline and ortho-aminophenol are obtained without using any environmentally undesirable liquid acid. The para-aminophenol selectivity reaches to 74.9% with 44.8% of nitrobenzene conversion under the optimal reaction conditions. And the amount of Al2O3 in SO4 (2-)/ZrO2-Al2O3 has great influence on the selectivity to para-aminophenol.