Selective Hydrogenation of m-Dinitrobenzene to m-Nitroaniline over Ru-SnOx/Al2O3 Catalyst

Series catalysts of Ru-SnOx/Al2O3with varying SnOxloading of 0–3 wt% were prepared, and their catalytic activity and selectivity have been discussed and compared for the selective hydrogenation ofm-dinitrobenzene (m-DNB) tom-nitroaniline (m-NAN). The Ru-SnOx/Al2O3catalysts were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and hydrogen temperature-programmed reduction (H2-TPR) and desorption (H2-TPD). Under the modification of SnOx, the reaction activity increased obviously, and the best selectivity tom-NAN reached above 97% at the complete conversion ofm-DNB. With the increasing of the SnOxloading, the amount of active hydrogen adsorption on the surface of the catalyst increased according to the H2-TPD analysis, and the electron transferred from Ru to SnOxspecies, as determined by XPS, inducing an electron-deficient Ru, which is a benefit for the absorption of the nitro group. Therefore, the reaction rate and product selectivity were greatly enhanced. Moreover, the Ru-SnOx/Al2O3catalyst presented high stability: it could be recycled four times without any loss in activity and selectivity.Keywords:Ru catalyst;SnOxdoping;hydrogenation;m-dinitrobenzene;m-nitroaniline;catalyst recycling