NiOx-promoted Cu-based catalysts supported on AlSBA-15 for chemoselective hydrogenation of nitroarenes

Chemoselective hydrogenation of aromatic nitro compounds to the corresponding anilines is an environmentally benign technology for the production of key intermediates in manufacturing of pharmaceuticals, agrochemicals, dyes and fine chemicals. Non-noble metal Cu-based catalysts have been reported as a low-cost alternative but suffer from poor activity. Herein, by fabricating nickel oxide promoted Cu catalysts, a promoted activity was obtained in supported Cu-Ni bimetal catalyst system. Characterizations such as H2-TPR and XPS indicate a strong interaction between Cu and Ni, which contributes to its high activity and selectivity in hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). Control experiments suggest that either monometallic copper or pure nickel oxide is less active for the reaction but the interaction of NiOx with Cu generates much more active species, resulting in significantly improved catalytic reactivity and selectivity. The activity was found to be highly dependent on the contents of Cu0 & Cu+ in Cu-Ni bimetal catalyst, as the specific reaction rates for hydrogenation of p-CNB grew linearly with the increment of Cu0 & Cu+ loadings. Kinetic studies and in-situ DRIFTS of p-CNB imply the 10Cu-5Ni/AlSBA-R catalyst possesses good capacity for the activation of hydrogen and nitro group, leading to high p-CNB conversion and p-CAN production. The present work provides a good example for understanding the interaction between Cu and nickel oxides, and helps to develop highly efficient non-noble metal catalysts for selective hydrogenation of aromatic nitro compounds to corresponding anilines.