Elsevier

Journal of Catalysis

Volume 381, January 2020, Pages 443-453
Journal of Catalysis

Host-guest chemistry immobilized nickel nanoparticles on zeolites as efficient catalysts for amination of 1-octanol

https://doi.org/10.1016/j.jcat.2019.11.021Get rights and content

Highlights

  • Nickel silicate and NiAl-LDHs phase were firmly anchored on USY zeolites.

  • The hierarchical USY@Ni materials featured well-dispersed Ni nanoparticles.

  • USY@Ni displayed elevated selectivity to primary amine in 1-octanol amination.

  • This strategy could achieve highly dispersed metal nanoparticles on zeolites.

Abstract

Nickel silicate and NiAl-LDHs (layered double-hydroxides) have been controllably fabricated on the crystal surface of Si-rich and Al-rich USY zeolites, respectively, through a distinctive in-situ hydrothermal growth approach. This was realized by the host-guest chemistry that induced chemoselective interactions between adscititious Ni source and constituent species of zeolite framework. Upon hydrogen reduction, nickel silicate and NiAl-LDHs were transformed to highly dispersed Ni nanoparticles (NPs) immobilized in the SiO2 and Al2O3 matrix, respectively, which were firmly anchored around the USY crystals. The controllable immobilization of Ni NPs created well preserved hierarchical porosity in USY zeolites. With highly dispersed metallic Ni active sites in Al2O3 matrix supported on USY zeolite, the USY@Ni-3 catalyst exhibited similar conversion but significantly enhanced selectivity in the reductive amination of 1-octanol to corresponding alkylamines in comparison to conventional Raney Ni catalyst.

Introduction

Alkylamines are extensively used as building blocks in a variety of high value-added chemicals including pharmaceuticals, polymers, dyes, pigments, and plasticizing agents, which play essential roles both in bulk and fine chemical industries [1], [2]. In the huge alkylamine family, aliphatic primary amines are of particular importance, serving as intermediates for further derivatization reactions, which stimulates researchers to develop eco-efficient synthesis route for the primary amines [3]. Nevertheless, the established traditional strategies for the primary amine synthesis, such as hydroamination of alkene or alkynes, and amination of aryl halides, encounter the disadvantages of poor selectivity, low atom-economy and toxic byproducts [4], [5]. As an alternative way, the reductive amination of the corresponding alcohols, producing water as the sole stoichiometric side product, emerges as an atom-economic and environmental-benign method for the production of amines [6].

The reductive amination of aliphatic alcohols proceeds via nucleophilic substitution reaction by means of borrowing hydrogen mechanism [7]. As described in Scheme 1, alcohol is firstly dehydrogenated to alkanal, which then translates to imine by condensation with ammonia, and finally the hydrogen returns to imine, forming primary amine [8], [9]. However, as the primary amine is more nucleophilic than ammonia to react with electrophiles, it is prone to over-alkylate the alcohol producing secondary amines and tertiary amines. Besides, the imine intermediate easily dehydrogenates to the corresponding nitrile or condensates with the primary amine giving rise to N-alkyl-imine and ammonia. Thus, the main challenge is to break thermodynamic equilibrium and minimize the selectivity of the nitrile and undesirable amines, in which case the choice of an effective catalyst is highly desired to achieve high activity and selectivity towards primary amine. The premier catalysts mainly focus on a variety of homogeneous pincer Ru complexes [10], [11], [12] and heterogeneous noble metals, such as supported Pd [13], Ru [14], Pt [15] and bimetallic catalysts [16], [17]. However, the above catalysts suffer from the problems of the catalyst recovery and the high cost of noble metals in practical industrial applications. Recent years have witnessed the development of a series of heterogeneous supported transition metal catalysts [18], [19], [20]. Amongst, Co-based catalysts are always performed in bimetallic format such as Ag-Co [21], [22], Co-Pd [17], Co-Ru [23], and Pt-Co catalysts [24], while the supported Cu catalyst was only reported to produce secondary amines [25]. Raney Ni exhibits excellent catalytic performance in alcohol amination yet the operation security hiders the wide application [26], [27]. Notably, supported-Ni catalysts can be employed as fascinating alternatives for the amination of a series of alcohols owing to the outstanding activity and stability [[28], [29], [30], [31]].

Shimizu and coworkers screened a series of metal-supported catalysts for the amination of 2-octanol and obtained the highest performance over Ni/γ-Al2O3 catalyst. They demonstrated the small-sized metallic Ni0 NPs on the alumina surface acting as the active species and acid-base sites of γ-Al2O3 support were indispensable for the high activity [32]. Similar conclusions that the reaction rate decreased with the increase of Ni particle size for alcohol amination were reported [33], [34]. For supported Ni catalyst, the major disadvantage lies in easy aggregation and poor dispersion in particular under high Ni content conditions. On this basis, Tomer et al. fabricated a series of Ni/Al2O3 catalysts with higher dispersion and narrower size distributions of Ni particles using cyclodextrins as the metal complex, which enhanced the catalytic properties in alcohol amination [35]. Whereas the interaction between Ni NPs and Al2O3 support was weak in above method and the participation of organic additives may result in environmental problems. In order to achieve highly efficient and stable catalyst for alcohol amination, it is highly desirable to develop green synthesis route to prepare the Ni-supported catalysts with high dispersion and strong metal species-support interaction.

Crystalline aluminosilicates possessing high surface area, intrinsic acidity and unique microporosity, have been utilized as important supports and catalysts for a variety of industrialized reactions [36], [37]. As one of the most used industrial catalysts, Y zeolite with the merits of adjustable acidity and feasible availability has been employed to catalyze the gas-phase 1-octanol amination [38]. Our group previously reported a host-guest chemistry for the in-situ formation of metal silicate and layered double-hydroxides (LDHs) precursors on Si-rich and Al-rich zeolite respectively, where the smaller particle size and narrower size distribution of metal particles were obtained arising from the Ni-O-Si and Ni-O-Al hetero-condensation/polymerization on the surface, resulting in the improved catalytic activity and stability in hydrogenation reactions [39], [40], [41].

On the basis of aforementioned researches, we here applied USY@Ni catalysts, synthesized by the above mentioned in-situ growth route, in the reductive amination of 1-octanol reaction. A series of USY zeolites with various Si/Al ratios were used as precursors to interact with Ni precursors in different ways, with high Si content ones to form nickel silicate and high Al content ones to NiAl-LDHs, which were then reduced to produce the USY@Ni catalysts. Detailed and thorough characterizations by spectroscopy and microscopy were employed to investigate the distinct USY precursors and the reduced USY@Ni catalysts, and the relationship between the structure properties and the catalytic performance was established preliminarily in the reductive amination of 1-octanol.

Section snippets

Synthesis of USY zeolites with different ratios

The parent USY zeolites with Si/Al molar ratios of ca. 3 and 6 were purchased from Wenzhou Huahua Group Co., Ltd, China. While USY zeolites with higher Si/Al molar ratios were synthesized by performing the acid treatments over the USY zeolite according to previous literatures [42]. The USY zeolite (Si/Al = 6) was firstly calcined in air at 600 °C for 5 h and then refluxed in 6 M HNO3 solution with a solid-to-liquid ratio of 1 g : 50 mL for 1 h and 18 h, to produce delauminated USY with the

Preparation and characterization of USY@Ni-P and USY@Ni materials

All the parent USY zeolites exhibited the well-defined reflections attributed to the typical FAU topology (Fig. S1). With the increase of Si/Al ratio, the reflection peak around 6.3° attributed to [1 1 1] plane gradually shifted to higher angle correspondingly (Fig. S1B), due to the lattice shrinkage after removing larger Al ions. Upon hydrothermal treatment in aqueous solution of nickel nitrate and base, Ni-Al layered hydrotalcite (NiAl-LDHs) were formed for USY@Ni-3-P and USY@Ni-6-P samples,

Conclusion

In summary, we fabricated well-dispersed Ni NPs robustly immobilized on USY zeolites with various Si/Al ratios through a facile in-situ growth method. Specifically, the NiAl-LDHs and nickel silicate precursors could be fabricated respectively on the Al-rich and Si-rich USY zeolites, from which highly dispersed Ni NPs were confined on the Al2O3 and SiO2 matrix upon reduction. Among the comparison of supported Ni zeolites with different Si/Al ratios and topologies in the reductive amination of

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.

Acknowledgement

This study is financially supported by China Ministry of Science and Technology under contract of 2016YFA0202804 and the National Natural Science Foundation of China (Grant No. 21872052, 21533002 and 21603075).

References (63)

  • A. Tomer et al.

    Facile preparation of Ni/Al2O3 catalytic formulations with the aid of cyclodextrin complexes: Towards highly active and robust catalysts for the direct amination of alcohols

    J. Catal.

    (2017)
  • A. Azzouz et al.

    Amination catalytique de l'octanol en phase gazeuse Action de l'ion uranyle sur l'activité catalytique de la faujasite Y

    J. Mol. Catal.

    (1991)
  • Z.G. Zhu et al.

    Postsynthesis of FAU-type stannosilicate as efficient heterogeneouscatalyst for Baeyer-Villiger oxidation

    Appl. Catal. A: Gen.

    (2016)
  • J. Zhao et al.

    Synthesis and characterization of mesoporous zeolite Y by using block copolymers as templates

    Chem. Eng. J.

    (2016)
  • X. Wang et al.

    Ni nanoparticles entrapped in nickel phyllosilicate for selective hydrogenation of guaiacol to 2-methoxycyclohexanol

    Appl. Catal. A: Gen.

    (2018)
  • M. Li et al.

    NiAl-layered double hydroxide/reduced graphene oxide composite: microwave-assisted synthesis and supercapacitive properties

    Electrochim. Acta

    (2014)
  • F. Trifirò et al.

    Nature and properties of nickel-containing mixed oxides obtained from hydrotalcite-type anionic clays

    Catal. Today

    (1994)
  • X. Li et al.

    Dry reforming of methane over Ni/La2O3 nanorod catalysts with stabilized Ni nanoparticles

    Appl. Catal. B: Environ.

    (2017)
  • A. Tomer et al.

    Mixed oxides supported low-nickel formulations for the direct amination of aliphatic alcohols with ammonia

    J. Catal.

    (2017)
  • B. Chauvin et al.

    Dealumination of faujasite, mazzite, and offretite with ammonium hexafluorosilicate

    J. Catal.

    (1990)
  • S.A. Lawrence

    Amines: Synthesis, Properties and Applications

    (2004)
  • T.E. Müller et al.

    Hydroamination: direct addition of amines to alkenes and alkynes

    Chem. Rev.

    (2008)
  • R. Kadyrov et al.

    Highly enantioselective hydrogen-transfer reductive amination: catalytic asymmetric synthesis of primary amines

    Angew. Chem.

    (2003)
  • J.F. Hartwig

    Evolution of a fourth generation catalyst for the amination and thioetherification of aryl halides

    Acc. Chem. Res.

    (2008)
  • G. Guillena et al.

    Hydrogen autotransfer in the N-alkylation of amines and related compounds using alcohols and amines as electrophiles

    Chem. Rev.

    (2010)
  • M. Pera-Titus et al.

    Catalytic amination of biomass-based alcohols

    ChemSusChem

    (2014)
  • X. Ye et al.

    Alcohol amination with ammonia catalyzed by an acridine-based ruthenium pincer complex: A mechanistic study

    J. Am. Chem. Soc.

    (2014)
  • Q. Yang et al.

    Substitution of alcohols by N-nucleophiles via transition metal-catalyzed dehydrogenation

    Chem. Soc. Rev.

    (2015)
  • H.J. Pan et al.

    Iron-catalyzed amination of alcohols assisted by Lewis acid

    Chem. Commun.

    (2015)
  • C. Gunanathan et al.

    Selective synthesis of primary amines directly from alcohols and ammonia

    Angew. Chem.

    (2008)
  • D. Pingen et al.

    Direct amination of secondary alcohols using ammonia

    Angew. Chem.

    (2010)
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