The nature of raney nickel, its adsorbed hydrogen and its catalytic activity for hydrogenation reactions (review)

Fouilloux, P.

doi:10.1016/0166-9834(83)80051-7

Cited by 155 publications

(63 citation statements)

References 76 publications

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“…The aluminum of the coatings was leached in alkaline solution yielding nanoporous Raney-Nickel structures. 38 A commercially available Zirfon Perl UTP-500 (Agfa) 39 separator with a thickness of approximately 460 μm separated the electrodes. In the cell assembly, the electrodes were pressed onto the diaphragm (zero gap configuration 10,40 ).…”

Section: Methodsmentioning

confidence: 99%

“…McCrory et al 20 reported similar activities of the employed catalysts in both electrolyzers. Normalized to mass, Raney-Nickel 38 and the employed Pt catalyst nanoparticles 43 feature surface areas in the order of 100 m 2 g −1 and 85 m 2 g −1 , respectively. In the acidic water electrolyzer, 0.2 mg cm −2 platinum and 2 mg cm −2 iridium oxide were employed, while the catalyst layer had thicknesses of approximately 10 μm.…”

Section: Model Parametrizationmentioning

confidence: 99%

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Acidic or Alkaline? Towards a New Perspective on the Efficiency of Water Electrolysis

Schalenbach

Tjarks

Carmo

et al. 2016

J. Electrochem. Soc.

275

182

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Water electrolysis is a promising technology for enabling the storage of surplus electricity produced by intermittent renewable power sources in the form of hydrogen. At the core of this technology is the electrolyte, and whether this is acidic or alkaline affects the reaction mechanisms, gas purities and is of significant importance for the stability and activity of the electrocatalysts. This article presents a simple but precise physical model to describe the voltage-current characteristic, heat balance, gas crossover and cell efficiency of water electrolyzers. State-of-the-art water electrolysis cells with acidic and alkaline electrolyte are experimentally characterized in order to parameterize the model. A rigorous comparison shows that alkaline water electrolyzers with Ni-based catalysts but thinner separators than those typically used is expected be more efficient than acidic water electrolysis with Ir and Pt based catalysts. This performance difference was attributed mainly to a similar conductivity but approximately 38-fold higher diffusivities of hydrogen and oxygen in the acidic polymer electrolyte membrane (Nafion) than those in the alkaline separator (Zirfon filled with a 30 wt% KOH solution In the endeavor to realize an environmentally-benign power supply infrastructure, water electrolysis for the production of hydrogen may prove a key technology for enabling energy conversion on a large scale.1,2 By applying a voltage to two electrodes immersed in an aqueous electrolyte, water can be electrochemically decomposed, evolving hydrogen at the negative pole, the cathode, and oxygen at the positive pole, the anode. During this process, protons or hydroxide ions must pass through the electrolyte to enable the electrochemical reactions at the electrodes. In order to achieve low extents of charge transport losses in electrolyzers, electrolytes with high conductivities are typically used. Such highly conductive electrolytes provide large quantities of ionic charge carriers (protons or hydroxide ions) and are thus either strong bases or acids. The reaction equations in acidic and alkaline aqueous regimes are displayed in Table I.Besides liquid aqueous electrolytes in combination with porous separators, polymer electrolyte membranes (PEMs) are typically used as electrolytes for water electrolysis and to separate the hydrogen and oxygen produced during operation.3 In PEMs, ionizable functional groups are embedded within a polymer matrix providing either mobile protons or hydroxide ions. 4 In an aqueous phase that is separated from the solid polymeric phase 5,6 the protons or hydroxide ions are dissolved but attracted to the oppositely charged ions of the functional group which are covalently bonded to the polymer matrix. As a result, the dissolved ions are captured inside the aqueous phase of the PEM. Hence, an advantage of solid PEMs is that pure water can supplied to the cell, which means that only the components that are in direct contact with the PEM are exposed to its corrosive alkaline or acidic aqueous ph...

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Section: Methodsmentioning

confidence: 99%

Section: Model Parametrizationmentioning

confidence: 99%

Acidic or Alkaline? Towards a New Perspective on the Efficiency of Water Electrolysis

Schalenbach

Tjarks

Carmo

et al. 2016

J. Electrochem. Soc.

275

182

View full text Add to dashboard Cite

show abstract

“…It is found that the desulfurization efficiency is closely related to the nature of the organosulfur molecules and the additives to the Ni-Al alloy. Skeletal Ni samples such as Raney Ni and RQ Ni have unique sponge structure and bear the merits of high surface area, high porosity, large pore size, low cost, and ready availability, [19][20][21] thus having the potentiality to be efficacious adsorbents for sulfur removal in clean fuel production. Moreover, since rapid quenching can lead to refined and more uniform microstructures as well as to deviations from equilibrium regarding phases and compositions, it can affect the physical and chemical properties of Raney-type adsorbents.…”

Section: Introductionmentioning

confidence: 99%

Comparative X-ray Photoelectron Spectroscopic Study on the Desulfurization of Thiophene by Raney Nickel and Rapidly Quenched Skeletal Nickel

Qiao

Xie

et al. 2005

J. Phys. Chem. B

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The desulfurization of thiophene on Raney Ni and rapidly quenched skeletal Ni (RQ Ni) has been studied in ultrahigh vacuum (UHV) by X-ray photoelectron spectroscopy (XPS). The Raney Ni or RQ Ni can be approximated as a hydrogen-preadsorbed polycrystalline Ni-alumina composite. It is found that thiophene molecularly adsorbs on Raney Ni or RQ Ni at 103 K. At 173 K, thiophene on alumina is desorbed, while thiophene in direct contact with the metallic Ni in Raney Ni undergoes C-S bond scission, leading to carbonaceous species most probably in the metallocycle-like configuration and atomic sulfur. On RQ Ni, the temperature for thiophene dissociation is about 100 K higher than that on Raney Ni. The lower reactivity of RQ Ni toward thiophene is tentatively attributed to lattice expansion of Ni crystallites in RQ Ni due to rapid quenching. The existence of alumina and hydrogen may block the further cracking of the metallocycle-like species on Raney Ni and RQ Ni at higher temperatures, which has been the dominant reaction pathway on Ni single crystals. By 473 K, the C 1s peak has disappeared, leaving nickel sulfide on the surface.

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“…RANEY® nickel, on the other hand, is an outstanding catalyst in the eld of transfer hydrogenation. [20][21][22][23] Its performance in the catalytic hydrogenation of nitroaromatic compounds however, still needs to be improved. Hereby, we report a combination of silver nanoparticles and RANEY® nickel as an effective catalyst in the reduction of a variety of nitroaromatic compounds as well as nitrofurazone, as a non-aromatic example, by NaBH 4 (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

A highly effective Ag–RANEY® nickel hybrid catalyst for reduction of nitrofurazone and aromatic nitro compounds in aqueous solution

Khorshidi

Ghorbannezhad

2017

RSC Adv.

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RANEY® nickel reduced Ag+ ions to form ultrafine spherical silver nanoparticles over itself, and the obtained hybrid material was used as catalyst for efficient and selective reduction of aromatic nitro compounds, and nitrofurazone as a non-aromatic example, in aqueous solution by using NaBH 4 as reducing agent. Other silver nanostructures with different morphologies such as silver nano-flowers were also prepared and their efficiency in the reduction process was evaluated. Ag-RANEY® nickel catalyst however, had superior advantages including mild reaction conditions, higher conversion yield, and reduction in aqueous solution at near ambient temperature. The catalyst was also recoverable and showed 5% decrease in efficiency after six successive runs.

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The nature of raney nickel, its adsorbed hydrogen and its catalytic activity for hydrogenation reactions (review)

Cited by 155 publications

References 76 publications

Acidic or Alkaline? Towards a New Perspective on the Efficiency of Water Electrolysis

Acidic or Alkaline? Towards a New Perspective on the Efficiency of Water Electrolysis

Comparative X-ray Photoelectron Spectroscopic Study on the Desulfurization of Thiophene by Raney Nickel and Rapidly Quenched Skeletal Nickel

A highly effective Ag–RANEY® nickel hybrid catalyst for reduction of nitrofurazone and aromatic nitro compounds in aqueous solution

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