In Situ Synthesized Silica‐Supported Co@N‐Doped Carbon as Highly Efficient and Reusable Catalysts for Selective Reduction of Halogenated Nitroaromatics

Abstract

AbstractSilica‐supported Co@N‐doped carbon (Co@CN/SiO2) catalysts were first prepared by a one‐step impregnation with a mixed solution of cobalt nitrate, glucose and urea, followed by in situ carbonization and reduction. The Co@CN/SiO2 catalysts were investigated for the selective reduction of nitro aromatics to the corresponding anilines using hydrazine hydrate. The Co@CN/SiO2‐500 carbonized at 500 °C exhibited the highest catalytic activity and excellent stability without any decay of activity after 6 cycles for the reduction of nitrobenzene. Both metallic Co atoms and Co−N species formed in the Co@CN/SiO2 catalysts were active, but the Co−N species were dominant active sites. The high activities of the Co@CN/SiO2 catalysts were attributed to the synergistic effect between the Co and N atoms, promoting heterolytic cleavage of hydrazine to form H+/H− pairs. Representative examples demonstrated that the Co@CN/SiO2‐500 could completely transform various halogen‐substituted nitro aromatics to the corresponding halogenated anilines with high TOFs and selectivity of >99.5 %.