Selective hydrogenation of chloronitrobenzene over supported-iridium catalyst

Ir/γ-Al2O3 catalyst used in selective hydrogenation of p-chloronitrobenzene (p-CNB) to produce p-chloroanilines (p-CAN) was prepared by impregnation method. Influences of catalyst activation temperature, reaction temperature, hydrogen pressure and reaction time on conversion of p-CNB and selectivity to p-CAN were studied. Under optimal conditions: catalyst activated at 120°, mole ratio of p-CNB to Ir 3 000, reaction temperature 50°C, hydrogen pressure 0.5 MPa, C2H5OH as solvent and reaction time 2.5 h, both conversion of p-CNB and selectivity to p-CAN can reach 100.0%. When o-CNB and m-CNB are used as reactants, selectivities to o-CAN and m-CAN can achieve 99.2% and 100.0% respectively. After the catalyst is reused for 8 times, conversion of p-CNB and selectivity to p-CAN can still keep at 100.0% and 98.2% respectively by prolonging reaction time to 5 h.