A new molecular pathway allows the chemoselective reduction of nitroaromatics on non-noble metal catalysts

[EN] At difference with noble metals, the oxophylic character of non-noble metals strongly facilitates the rupture of the N-O bonds in nitrobenzene, yielding nitrosobenzene as primary reaction intermediate. By combining periodic DFT calculations and kinetic studies, a direct pathway involving successive dissociation of N-O bonds followed by two hydrogenation steps, Ph-NO2 -> Ph-NO -> Ph-N -> Ph-NH -> Ph-NH2, has been found as most favorable on Ni catalysts. The rate determining step of the global process is the hydrogen transfer to adsorbed Ph-N intermediate. The catalyst surface becomes partly oxidized during reaction, which favors the vertical adsorption of the nitroaromatic compounds and enhances selectivity, while total surface oxidation leads to catalyst deactivation. It is proposed that both catalytic activity and selectivity of Ni and, possibly, other non-noble metals can be tuned by controlling the degree of oxidation of the metal surface. (C) 2018 Elsevier Inc. All rights reserved. KeywordsThis work has been supported by the Spanish Government through "Severo Ochoa Program" (SEV-2016-0683) and by Generalitat Valenciana through AICO/2017/153 Project. Red Espanola de Supercomputacion (RES) and Centre de Calcul de la Universitat de Valencia are gratefully acknowledged for computational resources and technical support. The authors also thank the Microscopy Service of UPV for kind help on measurements. R. M. acknowledges "La Caixa - Severo Ochoa" International PhD Fellowships (call 2015). L. L. thanks ITQ for providing a PhD scolarship.Millán-Cabrera, R.; Liu, L.; Boronat Zaragoza, M.; Corma Canós, A. (2018). A new molecular pathway allows the chemoselective reduction of nitroaromatics on non-noble metal catalysts. Journal of Catalysis. 364:19-30. https://doi.org/10.1016/j.jcat.2018.05.004193036