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

Wei, Haisheng; Liu, Xiaoyan; Wang, Aiqin; Zhang, Leilei; Qiao, Botao; Yang, Xiaofeng; Huang, Yanqiang; Miao, Shu; Liu, Jingyue; Zhang, Tao

doi:10.1038/ncomms6634

Cited by 1,005 publications

(705 citation statements)

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“…Activity for various reactions has so far been demonstrated for metals including Ir [483], Au [484], Pt [485][486][487][488], and this has motivated theoretical studies aimed at understanding how it is that a single atom can function as a catalyst [489]. Unfortunately, the complexity of the "FeO x " support, usually a reduced α-Fe 2 O 3 , means that the termination of the oxide is not known.…”

Section: Metalsmentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

498

463

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The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe 3 O 4 ), maghemite (γ-Fe 2 O 3 ), hematite (α-Fe 2 O 3 ), and wüstite (Fe 1-x O) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe 3 O 4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment, and because it is an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed.The best understood iron oxide surface at present is probably Fe 3 O 4 (100); the structure is known with a high degree of precision and the major defects and properties are well characterised. A major factor in this is that a termination at the Fe oct -O plane can be reproducibly prepared by a variety of methods, as long as the surface is annealed in 10 Such straightforward preparation of a monophase termination is generally not the case for other iron oxide surfaces. All available evidence suggests the oft-studied (√2×√2)R45° reconstruction results from a rearrangement of the cation lattice in the outermost unit cell in which two octahedral cations are replaced by one tetrahedral interstitial, a motif conceptually similar to well-known Koch-Cohen defects in Fe (0001) is the most studied hematite surface, but 2 difficulties preparing stoichiometric surfaces under UHV conditions have hampered a definitive determination of the structure. There is evidence for at least three terminations: a bulk-like termination at the oxygen plane, a termination with half of the cation layer, and a termination with ferryl groups. When the surface is reduced the so-called "bi-phase" structure is formed, which eventually transforms to a Fe 3 O 4 (111)-like termination. The structure of the bi-phase surface is controversial; a largely accepted model of coexisting Fe 1-x O and α-Fe 2 O 3 (0001) islands was recently challenged and a new structure based on a thin film of Fe 3 O 4 (111) on α-Fe 2 O 3 (0001) was proposed. The merits of the compet...

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Section: Metalsmentioning

confidence: 99%

Iron oxide surfaces

Parkinson

2016

Surface Science Reports

498

463

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“…Details of these studies are given in the work of Flyzani-Stephanopoulos et al [31,32,36,37] of Zhang et al [27][28][29][30] and Perez-Ramirez and co-workers [34], see also Christopher et al [38] and Thomas & Leary [39] From these studies, it is quite clear that individual atoms of the platinum group metals are the active centres for catalytic turnover. (We note, in passing, that in many of the reactions for which nanoparticles of Au on various supports are the catalysts, Fu et al [40,41] showed that the nanoparticles were spectator species, and that it was Au-O moieties that served as catalytically active centres.)…”

Section: Single-atom Heterogeneous Catalystsmentioning

confidence: 99%

“…At the Dalian Institute of Chemical Physics much work has been carried out, using individual atoms of the platinum group metals (Ir, Pt especially) supported on non-stoichiometric FeO x . Wei et al [29] have demonstrated that single-atom catalysts (SACs) of Pt on FeO x are excellent catalysts for the chemoselective hydrogenation of a variety of nitroarenes to their amino products (without hydrogenating benzene rings or carbonyl groups attached to them) under mild conditions, typically at 40°C, with contact times ranging from 10 to 120 min, conversions of 90-100% and selectivities from 90 to 99.7% [29].…”

Section: Single-atom Heterogeneous Catalystsmentioning

confidence: 99%

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Reflections on the value of electron microscopy in the study of heterogeneous catalysts

Thomas

2017

Proc. R. Soc. A.

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Electron microscopy (EM) is arguably the single most powerful method of characterizing heterogeneous catalysts. Irrespective of whether they are bulk and multiphasic, or monophasic and monocrystalline, or nanocluster and even single-atom and on a support, their structures in atomic detail can be visualized in two or three dimensions, thanks to high-resolution instruments, with sub-Ångstrom spatial resolutions. Their topography, tomography, phase-purity, composition, as well as the bonding, and valence-states of their constituent atoms and ions and, in favourable circumstances, the short-range and long-range atomic order and dynamics of the catalytically active sites, can all be retrieved by the panoply of variants of modern EM. The latter embrace electron crystallography, rotation and precession electron diffraction, X-ray emission and high-resolution electron energy-loss spectra (EELS). Aberration-corrected (AC) transmission (TEM) and scanning transmission electron microscopy (STEM) have led to a revolution in structure determination. Environmental EM is already playing an increasing role in catalyst characterization, and new advances, involving special cells for the study of solid catalysts in contact with liquid reactants, have recently been deployed.

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“…[1][2][3] About 85% of aniline is produced via the catalytic hydrogenation of nitrobenzene (NB) using gaseous H 2 under either liquid or gas phase conditions as it is environmentally benign and water is the only by-product in this reaction. [4] Moreover nitration of aromatic compounds is a very well established and optimised technology that makes nitroarenes a readily available feedstock for the production of bulk and/or fine chemicals.…”

Section: Introductionmentioning

confidence: 99%

Supported Bimetallic AuPd Nanoparticles as Catalyst for the Solvent-Free Selective Hydrogenation of Nitroarenes

Qu¹,

Macino²,

Iqbal³

et al. 2018

Preprint

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Abstract:Selective hydrogenation of nitrobenzene was carried out under solvent-free conditions using supported AuPd nanoparticles catalyst, prepared by modified impregnation method (M Im ), as efficient catalyst. >99% yield of aniline (AN) was obtained after 15 hours at 90 °C, 3 bar H 2 that can be used without any further purification or separation, therefore reducing cost and energy input. Supported AuPd nanoparticles catalyst, prepared by M Im , was found to be active and stable even after 4 recycle experiments whereas the same catalyst prepared by S Im deactivated during the recycle experiments.The most effective catalyst was tested for the chemoselective hydrogenation of 4-chloronitrobenzene (CNB) to 4-chloroaniline (CAN). The activation energy of CNB to CAN was found to be 25 kJ mol -1 , while that of CNB to AN was found to be 31 kJ mol -1 . Based on this, the yield of CAN was maximized (92%) by lowering the reaction temperature to 25 °C.

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

Cited by 1,005 publications

References 36 publications

Iron oxide surfaces

Iron oxide surfaces

Reflections on the value of electron microscopy in the study of heterogeneous catalysts

Supported Bimetallic AuPd Nanoparticles as Catalyst for the Solvent-Free Selective Hydrogenation of Nitroarenes

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