Preparation and reactivity of UV light-reduced Pd/α-Fe2O3 catalyst towards the hydrogenation of o-chloronitrobenzene

Abstract

A type of Pd/α-Fe2O3 catalyst was synthesized by a convenient UV light-induced reduction in the presence of Fe3+ ions. The synthesized Pd/α-Fe2O3 particles were characterized by X-ray diffraction (XRD), low-resolution transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectrum (XPS), atomic force microscope (AFM), scan electron microscopy with energy dispersion spectra (SEM-EDS), FT-IR and BET. Related characterizations confirm that UV light-induced reduction is a feasible, simply and environment-friendly method for the preparation of supported catalysts containing active metal. Furthermore, hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN) by the selected Pd(0.5%)/α-Fe2O3 was investigated systematically. The α-Fe2O3-supported Pd catalyst was found to exhibit good catalytic activity and selectivity for the o-CNB reduction under mild conditions. The hydrogenation of o-CNB over the resulting Pd-based catalyst gave a 100% o-CNB conversion and 91.4% selectivity of o-CAN under the reaction conditions of 50°C, 2h, 1MPa hydrogen pressure, no-CNB/nPd=6000:1. Moreover, the resulting Pd-based catalyst remained higher hydrogenation reactivity after three runs even if a sharply decrease in activity was observed at the fourth run. The obtained results reveal the as-prepared Pd/α-Fe2O3 is an efficient catalyst for the hydrogenation of o-CNB even at a high level of substrate concentration.