Hydrogenation of Nitrobenzene over a Pd/Al2O3 Catalyst - Mechanism and Effect of the Main Operating Conditions

Abstract

The catalytic hydrogenation of nitrobenzene (NB) was studied in a three-phasebasket reactor with a commercial Pd/Al2O3 sample as catalyst. The kinetic experiments allowed a better understanding of the mechanism behind the formation ofaniline (ANL) and by-products, a topic not yet well comprehended. The effect ofsome operating conditions was studied and the existence of more by-productsthan mentioned in the literature was stated; specifically, benzene formation wasverified. Both the reaction kinetics and selectivity were found to be stronglydependent on the temperature, while the effect of total pressure is not that pronounced. Moreover, the high selectivity of the catalyst used in the present workwas proved, and as such the deep hydrogenation of ANL to form by-products onlyoccurs in considerable extension when the NB concentration in the reaction mixture becomes negligible.