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

Abstract

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–N x 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–N x 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.

Enhancing the catalytic performance of Co–N–C derived from ZIF-67 by mesoporous silica encapsulation for chemoselective hydrogenation of furfural

“…1G) reveals that the lattice distance of Co nanoparticles was 0.205 nm, which was assigned to the metallic Co (111) plane. 35,37 This was in accordance with the XRD results. Co–N–C@mSiO 2 -20–600 and Co–N–C@mSiO 2 -20–800 exhibited ∼7.9 nm and 10.5 nm diameter Co nanoparticles, respectively (Fig.…”

“…37 Recently, Liu et al have communicated that the nitrogen species could modify the electronic property of Co in Co-N x species and then enhance H 2 adsorption and dissociation, thereby improving the nitrobenzene hydrogenation activity of Co-based catalysts from a Co-Zn MOF. 37 Hence we speculated that the modified electronic nature of Co by N tuned the adsorption behaviour of H 2 and then enhanced the catalytic hydrogenation performance of Co-N-C@mSiO 2 . Finally, a negligible activity was observed when the reaction proceeded under N 2 instead of H 2 (Table 1, entry 13), indicating that no transfer occurred during furfural hydrogenation.…”

“…[33][34][35] Very recently, we and other groups have found that Co-N x species were the catalytically active sites for the hydrogenation of nitroarenes. [35][36][37] Gong et al reported that the confined Co nanoparticles with Co-N x active sites, derived from the pyrolysis of ZIF-67, promoted the selective hydrogenation of biomass-derived chemicals. 38 Despite all these developments, the amount of Co-N x species was inevitably reduced because of the aggregation of Co nanoparticles and collapse of the resulting matrix structure after high-temperature treatment (e.g.…”

Cyclic Extrusion Synthesis of Mesoporous Carbon-Supported Metal Catalysts for Selective Hydrogenation

“…50 Therefore, its reaction rate is proportional to the starting concentration of reactants, and the reaction rate is increased by the increase of hydrogen pressure. 51 When the H 2 spatial pressure was 2MPa, the highest selectivity of AN (> 99%) would be obtained. Although the conversion rate still raised when the H 2 spatial pressure increased to 3MPa, 2MPa was selected due to the poor selectivity under 3MPa H 2 spatial pressure.…”

Palladium Nanoparticles Inset into the Carbon Sphere with Robust Acid Resistance for Selective Hydrogenation of Chloronitrobenzene

“…However, numerous acid residues are introduced into the crude nitroaromatics of the complicated group substitutions on the benzene molecule for obtaining special characteristics, including halogenation and nitrogenization . Besides, a side reaction of dehalogenation existing in the hydrogenation reaction of halogenated nitrobenzene is inevitable in the industrial processes. , Our previous works ,,,, committed to suppressing the dehalogenation of halogenated nitrobenzene catalytic hydrogenation by heteroatom doping, while the dehalogenation (halogen acid) was still not inhibited completely (∼0.1%). Metal leaching by acid corrosion not only shortens the lifetime of catalysts but also pollutes productions, especially for the fields of pharmacy and the liquid crystal display (LCD) panel industry.…”