Well-Defined MOF-Derived Hierarchically Porous N-Doped Carbon Materials for the Selective Hydrogenation of Phenol to Cyclohexanone

Abstract

Metal organic framework (MOF) derivatives, porous N-doped carbons (CN), can be used as catalyst carriers owing to their excellent structural properties. The microstructures of MOF-derived carbon materials are affected considerably by the atmosphere in which the parent MOFs are pyrolyzed. In this study, a hierarchically porous N-doped carbon hybrid of carbon nanotubes and a porous carbon framework (denoted CN-H) was fabricated by pyrolysis in a H2/Ar atmosphere followed by acid etching, and subsequently, a Pd@CN-H catalyst was synthesized by the addition of Pd nanoparticles on the porous N-doped carbon support. The pyrolysis atmosphere and etching treatment significantly affected the morphology, specific surface area, meso/macropore ratio, and composition of the porous N-doped carbon materials, as well as the catalytic properties of the Pd@CN catalysts for the selective hydrogenation of phenol to produce cyclohexanone. Nitrogen adsorption–desorption measurements and inductively coupled plasma atomic absorption spectroscopy analyses confirmed that pyrolysis in a H2/Ar atmosphere and acid etching significantly increased the number of meso/macropores in Pd@CN-H, thus enhancing the Pd loading and phenol adsorption. As a result of the increased porosity, Pd loading, and phenol adsorption, the cyclohexanone selectivity and phenol conversion were improved. Furthermore, the as-fabricated Pd@CN-H catalyst displayed good reusability in recycling tests. These results provide insights into the synthesis of MOF-derived hybrid carbon materials and their possible utilization in catalysis.

Hierarchical N-Doped CuO/Cu Composites Derived from Dual-Ligand Metal–Organic Frameworks as Cost-Effective Catalysts for Low-Temperature CO Oxidation

“…The isotherms of the three samples could be categorized as type IV with the H 3 hysteresis loop, in accordance with mesoporous materials. 25,27,28 As comparison, N-CuO/Cu exhibited higher Brunauer−Emmett−Teller surface areas (S BET , 66.099 m 2 /g) than samples N-CuO(ex) (9.882 m 2 /g) and N-CuO(op) (34.421 m 2 /g). The increase in S BET can be attributed to the inherited hierarchical flower-like framework providing more complex spatial components for N-CuO/Cu.…”

“…The large surface area, pore volume, and hierarchical pore structure were very beneficial to the exposure of active sites and rapid transportation of gas molecules to catalytic sites. 25,50 As shown in the SEM images of the N-doped CuO/Cu sample, the self-assembly of nanoparticles was directed from CuBDC-MeIM(rt) to construct N-CuO/Cu hierarchical structures, which had an inherited flower-like structure consisting of nanosheets (Figure 5a presented a sheet-like structure, with a size of approximately 100 μm × 5 μm (Figure S5), there was no obvious hierarchical structure, this was attributed to the fact that CuBDC-MeIM(rt) had the complete and well-shaped flower-like structure, and using fusiform basic copper nitrate as the metal node, the strong bond between the metal and the ligand prevented the collapse of the structure after pyrolysis. 51 The morphological properties of CuBDC-MeIM(rt) pyrolyzed at 573 K significantly affected the physicochemical properties of MOF-derived composites.…”

Atom Doping Engineering of Metal/Carbon Catalysts for Biomass Hydrodeoxygenation

“…Additionally, some reactions may be affected by the mass transfer effect, such as catalytic reactions occurring at the solid−liquid interface, so novel catalysts can be developed to meet the specific requirements of the reactions. For example, Shao et al 179 synthesized a hierarchical porous carbon material with high porosity by a simple and efficient route.…”

Rebound behaviors of hydrophilic particle on gas bubble: effect of particle size and liquid properties

“…It is seen that the N-doped carbon particles are very hydrophobic. The preparation of the N-doped carbon particles has been reported by Shao et al 32 To realize phenol hydrogenation, these supports are loaded with very small amounts of Pd, which do not change the hydrophilicity and hydrophobicity of the supports.…”