Efficient chemoselective hydrogenation of halogenated nitrobenzenes over an easily prepared γ-Fe2O3-modified mesoporous carbon catalyst

Abstract

Efficient chemoselective hydrogenation of halogenated nitrobenzenes using low-cost catalysts is an important research area of applied catalysis. In this work, a Fe metal organic gel (Fe-MOG) was prepared via metal coordination interaction between Fe(NO₃)₃·9H₂O and 1,4-naphthalenedicarboxylic acid. Fe-MOG was used as the precursor for the fabrication of a low-cost γ-Fe₂O₃-modified mesoporous carbon catalyst (γ-Fe₂O₃/MC) through carbonization under an N₂ atmosphere at high temperature. The obtained γ-Fe₂O₃/MC catalyst had high catalytic activity and selectivity for the hydrogenation of Cl⁻, Br⁻ and I⁻ functionalized nitrobenzenes without any obvious dehalogenation. The hydrogenation reactions had a product yield and selectivity for the corresponding halogenated aniline of 100% when using hydrazine hydrate as the reducing agent. The whole hydrogenation reaction process was environmentally friendly because of its harmless byproducts (H₂O and N₂). In addition, the γ-Fe₂O₃/MC catalyst was recyclable because of the magnetism of the γ-Fe₂O₃ active sites. The catalytic activity of the γ-Fe₂O₃/MC catalyst was not obviously decreased after being recycled five times. Therefore, the γ-Fe₂O₃/MC catalyst has great potential for future applications in the chemoselective hydrogenation of halogenated nitrobenzenes.