Elsevier

Molecular Catalysis

Volume 485, April 2020, 110838
Molecular Catalysis

Well-constructed Ni@CN material derived from di-ligands Ni-MOF to catalyze mild hydrogenation of nitroarenes

https://doi.org/10.1016/j.mcat.2020.110838Get rights and content

Highlights

  • Ni@CN porous materials are synthesized by one-step pyrolysis of a metal-organic framework Ni-MOF.

  • Ni@CN-500 catalyst shows the highest activity, which is superior to those observed with single ligand catalyst.

  • Some challenging nitroarenes are readily hydrogenated with the yield over 90 % and aniline selectivity up to >99 %.

  • Ni@CN-500 is recyclable and versatile for transfer hydrogenation various nitroarenes compounds.

Abstract

1,3,5-benzenetricarboxylate (BTC) and 4,4′-bipyridine (BIPY) are employed in the synthesis of dual ligands Ni-MOFs. The magnetic Ni@CN nanocatalyst is prepared by direct pyrolysis of Ni-MOFs in N2 atmosphere, which exhibited excellent activity in selective hydrogenation of nitrobenzene (NB) to aniline (AN) at 60 °C, 2.0 MPa H2. The conversion of NB can reach 99.1 mol%, and the selectivity of AN is over 99 %. A series of characterizations are obtained by XRD, Raman, XPS, SEM, TEM, TPR and TGA. It is found that the synergic effect of Ni species and N contributes to the increase of catalytic activity of the catalyst. Cycling tests proved that the prepared catalyst could be reused ten times without a visible reduction in catalytic activity of hydrogenation. The excellent stability and activity of Ni@CN nanocatalyst could be assigned to the porosity of carbon material doped with nitrogen, derived from dual ligands Ni-MOFs.

Graphical abstract

The hydrogenation of nitrobenzene to aniline has been effectively carried out over Ni@CN-x catalysts. The results show that Ni@CN-500 composite catalyst exhibits an excellent performance to achieve 99.1 mol% conversion of nitrobenzene and >99 % selectivity of aniline under reaction conditions of 2.0 MPa H2 and 60 °C.

  1. Download : Download full-size image

Introduction

It is a great challenge to pay attention to the environment and reduce the energy consumption and chemical waste in chemical transformation [1]. The selective hydrogenation of nitroarenes into corresponding anilines is widely used in the manufacture of various polymers, drugs, agricultural chemicals, dyes and pigments [[2], [3], [4]]. In the traditional industry, functionalized AN is mainly obtained by large amount of reducing agents such as sodium bisulfite, hydrazine hydrate or some non-recyclable non-noble metal ions (such as tin, iron, zinc), which will bring huge risks to the environment [5]. Therefore, there is an urgent need to develop an efficient and environmentally friendly way to produce AN. Catalytic hydrogenation with hydrogen as a hydrogen source is undoubtedly the best way to produce AN, owning to its low cost, cleanliness and ease of production. Nevertheless, in the past, most of the catalysts used in the catalytic hydrogenation reaction inevitably produced some by-products, such as azoxy derivatives, nitroso and hydroxylamines [[6], [7], [8]]. This is because the strong adsorption of intermediate products to catalysts increases the difficulty of selective hydrogenation of substituents on nitroarenes with other reducible groups (e.g., single bondOH, CC, CO, CN and Csingle bonddouble bondsingle bonddouble bondsingle bondsingle bondl) [[9], [10], [11], [12]].

Most of the literature on the production of aromatic amines is heavily dependent on precious metals, such as Pd, Pt, Rh, and Ru. [1,[13], [14], [15], [16]] The use of these precious metal catalysts can greatly increase the activity of the reaction, but the selectivity often does not perform well. Although selectivity can be improved by adding transition metal salts and additives to the reaction, the addition of these metal salts and additives poisons the reactive sites and reduces the reactivity, and the cost itself is high. Furthermore, it gives new problems to the environment [17,18]. Gold-silver based catalysts exhibit good selectivity for nitro compounds, but lower conversion due to its poor capacity of hydrogen dissociation [19,20]. With the increasingly strict environmental requirements in today's society, green chemistry is being called upon by more and more people, and heterogeneous catalysts for hydrogenation reactions play an important role in this process due to their easy separation characteristics. Therefore, there is an urgent need to develop a non-precious metal heterogeneous catalyst used for the hydrogenation of nitro compounds under mild conditions [21,22].

MOF is an inorganic-organic material composed of inorganic nodes and organic linkers [[23], [24], [25]]. Compared with traditional porous materials, MOFs have many characteristics such as high specific surface area, high porosity, and adjustable pore size [26,27]. Therefore, MOFs are often used in many fields such as catalysis [[28], [29], [30], [31]], gas adsorption and separation [32,33], storage [34], fluorescence and molecular sensors [[35], [36], [37], [38]]. Especially in the field of heterogeneous catalysis [39,40], MOFs materials and their derivatives are considered to be promising. At present, the preparation of porous carbon-containing metals by means of pyrolysis of MOFs is a relatively simple method [41], and the application of the MOFs derivatives obtained after pyrolysis in hydrogenation reaction is also very common, e.g. in the hydrogenation of nitrobenzene to aniline [[42], [43], [44], [45], [46], [47]].

Very recently, our group has published some works on the one step hydrogenation of NB [13,48], the hydrogenation product is cyclohexylamine. Herein, we report a simple preparation method for active N-doped Ni@CN catalyst and its applications in the selective catalytic hydrogenation of nitroarenes under mild conditions. The metal nanoparticles are uniformly distributed on the porous carbon, and the interaction between the nitrogen atoms and the nickel facilitates the formation of relatively electron-deficient and ultra-small sized nickel clusters.

Section snippets

Materials

The chemicals used include Ni(NO3)2·6H2O (98 %, Sinopharm), 1,3,5-benzenetricarboxylate (BTC, Aladdin), 4,4′-bipyridine (BIPY, Aladdin), DMF (98 %, Sinopharm), nitrobenzene (NB, 98 %, Sinopharm). All other chemicals are analyzed for purity.

Synthesis of Ni-MOF

Nickel nitrate hexahydrate (Ni(NO3)2•6H2O, 0.876 g, 3 mmol) as the metal source, BTC (2.270 g, 10.8 mmol) and BIPY (1.406 g, 9 mmol) as ligands, DMF as solvent are added in the PTFE liner. The ratio of metal to each ligand is (3 mmol: 10.8 mmol: 9 mmol = 1:

Characterization of Ni@CN-x materials

Fig. 1(a) shows thus-synthesized Ni-MOF precursor and the simulated XRD patterns. The powder XRD pattern of the Ni-MOF matched well with the standard XRD pattern. The XRD patterns of Ni@CN-x catalysts obtained by calcining Ni-MOF precursor at different temperatures is shown in Fig. 1(b). The XRD patterns of the Ni@CN-x nanocatalysts exhibited three diffraction peaks at around 44.5°, 51.8° and 76.4°, corresponding to the characteristic diffractions of Ni [111], [200] and [220] lattice planes of

Conclusion

The dual-ligands Ni-MOF is synthesized by hydrothermal method, where BTC and BIBY provide carbon source and nitrogen source, which is then pyrolyzed under N2 atmosphere to receive Ni@CN-x catalysts. The best crystallization and pyrolysis conditions are discussed, followed by a series of structural characterizations and catalytic tests. The effects of reaction solvent, temperature, time and H2 pressure on the hydrogenation reaction are investigated systematically. In the hydrogenation of NB, the

Author contributions

All authors contributed to the writing of this manuscript and approved the final version of the manuscript.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

Financial support from the National Natural Science Foundation of China (21673069, 21503074, 21571055), Hubei Province Students Innovation and Entrepreneurship Training Foundation of China (201710512045), Hubei Province Outstanding Youth Foundation (2016CFA040), and Applied Basic Frontier Project of Wuhan Science and Technology Bureau (201911061251001).

References (51)

  • Y. Qu et al.

    Hydrogenation of nitrobenzene catalyzed by Pd promoted Ni supported on C60 derivative

    Appl. Surf. Sci.

    (2019)
  • G. Deniau et al.

    Carbon-to-metal bonds: electrochemical reduction of 2-butenenitrile

    Surf. Sci.

    (2006)
  • S. Zhang et al.

    High catalytic activity and chemoselectivity of sub-nanometric Pd clusters on porous nanorods of CeO2 for hydrogenation of nitroarenes

    J. Am. Chem. Soc.

    (2016)
  • H. Blaser

    A golden boost to an old reaction

    Science

    (2006)
  • H. Wei et al.

    FeOx-supported platinum aingle-atom and pseudo-single-atom catalysts for chemoselective hydrogenation of functionalized nitroarenes

    Nat. Commun.

    (2014)
  • G. Vilé et al.

    Structure and reactivity of supported hybrid platinum nanoparticles for the flow hydrogenation of functionalized nitroaromatics

    ACS Catal.

    (2015)
  • D. He et al.

    An exceptionally active and selective Pt–Au/TiO2 catalyst for hydrogenation of the nitro group in chloronitrobenzene

    Green Chem.

    (2012)
  • X. Liu et al.

    Gold-catalyzed direct hydrogenative coupling of nitroarenes to synthesize aromatic azo compounds

    Angew. Chem. Int. Ed.

    (2014)
  • E.H. Boymans et al.

    A study on the selective hydrogenation of nitroaromatics to N-arylhydroxylamines using a supported Pt nanoparticle catalyst

    Catal. Sci. Technol.

    (2015)
  • Z. Sun et al.

    The solvent-free selective hydrogenation of nitrobenzene to aniline: an unexpected catalytic activity of ultrafine Pt Nanoparticles deposited on carbon nanotubes

    Green Chem.

    (2010)
  • W.C. Cheong et al.

    Isolated iron single atomic site catalyzed chemoselective transfer hydrogenation of nitroarenes to arylamines

    ACS Appl. Mater. Interfaces

    (2019)
  • X. Lu et al.

    Highly selective one-step hydrogenation of nitrobenzene to cyclohexylamine over the supported 10% Ni/carbon catalysts doped with 3‰ Rh

    RSC Adv.

    (2016)
  • W. Shi et al.

    Enhanced chemoselective hydrogenation through tuning the interaction between Pt nanoparticles and carbon supports: insights from identical location transmission electron microscopy and X-ray photoelectron spectroscopy

    ACS Catal.

    (2016)
  • S. Cai et al.

    Highly active and selective catalysis of bimetallic Rh3Ni1 nanoparticles in the hydrogenation of nitroarenes

    ACS Catal.

    (2013)
  • Q. Yang et al.

    Ru/UiO-66 catalyst for the reduction of nitroarenes and tandem reaction of alcohol oxidation/knoevenagel condensation

    ACS Omega

    (2018)
  • Cited by (62)

    View all citing articles on Scopus
    View full text