ZIF-Derived Co-Based Catalysts for Efficient Hydrogenation of Aromatic Compounds: the Study of the Co–Nx Active Sites

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This work reports a highly effective Co-based catalyst prepared by pyrolyzing a Co–Zn bimetallic metal–organic framework (CoZn-BMZIFs). This Co–Zn@NC catalyst takes advantage of the highly dispersed Co nanoparticles, large surface area, and high concentration of Co–Nx active species to facilitate the catalytic performance in an aromatic hydrogenation reaction using nitrobenzene as the probe substance. The introduction of a Zn element in the precursor enhances the Co nanoparticle dispersion and increases the specific surface area during pyrolysis. Furthermore, the formation of Co–Nx active species can further improve the catalytic activity. 2Co–1Zn@NC-800 shows the best catalytic performance with an aniline yield of >99.5% under mild conditions. The kinetic study was also carried out to obtain the apparent activation energy of the reaction. The density functional theory (DFT) calculation reveals that nitrogen doping in the catalysts could enhance the H2 adsorption and dissociation by lowering the reaction energy and the energy barrier.