Reduction kinetics of Goro nickel oxide using hydrogen

Utigard, T. A.; Wu, Min; Plascencia, Gabriel; Marin, Timothy W.

doi:10.1016/j.ces.2004.11.024

Cited by 101 publications

(78 citation statements)

References 16 publications

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“…A reaction interface moves from the edge of a cylinder (R2) or the surface of a sphere (R3) toward the solid reactant centre with a constant rate. Equations for geometrical contraction models are the same as those for a shrinking core model controlled by chemical reaction [18,37,38].…”

Section: Kinetics Modellingmentioning

confidence: 99%

“…Although many studies suggested that reduction kinetics of NiO, either bulk or supported, obeyed geometrical contraction models [18,23,37,42,43], nucleation and nuclei growth models also found applications in kinetic analysis of NiO reduction [38,39,44,45]. Hossain et al [39] compared the nucleation and nuclei growth model with the geometrical contraction model when studying reduction kinetics of a Co-Ni/Al 2 O 3 catalyst.…”

Section: Kinetics Modellingmentioning

confidence: 99%

“…In particular, whether HAc, as a bio-oil model compound, has the ability to perform the reduction step will be investigated. To the authors' knowledge, little research has been done on the reduction of metal oxides by oxygenated hydrocarbons, although reduction with simple molecules such as H 2 [17][18][19], CH 4 [20][21][22] and CO [23] have been studied in the fields of metallurgy, catalysis and chemical looping technology.…”

Section: Introductionmentioning

confidence: 99%

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Nickel catalyst auto-reduction during steam reforming of bio-oil model compound acetic acid

Cheng

Dupont

2013

International Journal of Hydrogen Energy

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Transition metal catalysts widely used in refineries are provided as oxides and require pre-reduction to become activated. The auto-reduction of a NiO/Al 2 O 3 catalyst with acetic acid (HAc) followed by HAc steam reforming was investigated in a packed bed reactor. Effects of temperature and molar steam to carbon ratio (S/C) on reduction kinetics and catalyst performance were analysed. Results showed that a steady steam reforming regime along with complete NiO reduction could be obtained after a coexistence stage of reduction and reforming. A 2D nucleation and nuclei growth model fitted the NiO auto-reduction. The maximum reduction rate constant was attained at S/C=2. Steam reforming activity of the auto-reduced catalyst was just below that of the H 2 -reduced catalyst, probably attributed to denser carbon filament formation and larger loss of active Ni. Despite this, a H 2 yield of 76.4% of the equilibrium value and HAc conversion of 88.97% were achieved at 750 °C and S/C=3.

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Section: Kinetics Modellingmentioning

confidence: 99%

Section: Kinetics Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nickel catalyst auto-reduction during steam reforming of bio-oil model compound acetic acid

Cheng

Dupont

2013

International Journal of Hydrogen Energy

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“…The unreacted shrinking core model takes into account the particle size and the pore structure [26][27][28]. The kinetic is governed by three limiting phenomena; diffusion in the external gas film, diffusion into particles, and chemical reaction [26,29].…”

Section: Kinetic Modelsmentioning

confidence: 99%

Numerical Modeling of Oxygen Carrier Performances (NiO/NiAl2O4) for Chemical-Looping Combustion

Blas¹,

Dutournié

Jeguirim

et al. 2017

Energies

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Abstract:This work was devoted to study experimentally and numerically the oxygen carrier (NiO/NiAl 2 O 4 ) performances for Chemical-Looping Combustion applications. Various kinetic models including Shrinking Core, Nucleation Growth and Modified Volumetric models were investigated in a one-dimensional approach to simulate the reactive mass transfer in a fixed bed reactor. The preliminary numerical results indicated that these models are unable to fit well the fuel breakthrough curves. Therefore, the oxygen carrier was characterized after several operations using Scanning Electronic Microscopy (SEM) coupled with equipped with an energy dispersive X-ray spectrometer (EDX). These analyses showed a layer rich in nickel on particle surface. Below this layer, to a depth of about 10 µm, the material was low in nickel, being the consequence of nickel migration. From these observations, two reactive sites were proposed relative to the layer rich in nickel (particle surface) and the bulk material, respectively. Then, a numerical model, taking into account of both reactive sites, was able to fit well fuel breakthrough curves for all the studied operating conditions. The extracted kinetic parameters showed that the fuel oxidation was fully controlled by the reaction and the effect of temperature was not significant in the tested operating conditions range.

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“…[13][14][15][16] A few investigations were conducted to investigate the influence of reduction temperature on the pure initial Ni particle microstructure. Plascencia and Utigard 17 and Utigard et al 18 have studied the reduction process of NiO particles at different temperatures. It is shown that different initial reduction temperatures lead to totally different morphologies of Ni particles in millimeter-scale.…”

mentioning

confidence: 99%

Quantitative Study on the Correlation between Solid Oxide Fuel Cell Ni-YSZ Composite Anode Performance and Reduction Temperature Based on Three-Dimensional Reconstruction

Jiao

Shikazono

2015

J. Electrochem. Soc.

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The effects of reduction temperature on the initial performances and short-time durability of nickel-yttria-stabilized zirconia composite solid oxide fuel cell anodes were investigated. The anode microstructures before and after 100 hours operation were quantitatively analyzed by three-dimensional reconstruction based on focused ion beam-scanning electron microscopy technique. The anode reduced at 500 • C showed the worst initial performance and stability in operation which was attributed to the smallest specific nickel-yttria-stabilized-zirconia interface area and the very porous nickel formed in low temperature reduction. The anode reduced at 800 • C showed the smallest polarization resistance which was attributed to the largest active three phase boundary density. The anode reduced at 1000 • C showed the most stable performance with polarization resistance enhanced in operation, which was attributed to the largest specific nickel-yttria-stabilized-zirconia interface area and the dense nickel phase formed in high temperature reduction. It is found that the performance of anode is determined not only by the active three phase boundary density but also the interface bonding between nickel and yttria-stabilized-zirconia in composite anode. Nickel-yttria-stabilized-zirconia interfacial bonding can be enhanced with the increase of reduction temperature, which is able to inhibit the nickel sintering and improve the anode performance stability in long-time operation. Solid oxide fuel cell (SOFC, hereafter), as a high efficiency and fuel flexibility energy conversion device, has been attracting more and more attentions in recent decades, 1,2 while long time operation stability of SOFC electrodes remain as one of the main challenges. For the nickel-yttria-stabilized-zirconia (Ni-YSZ, hereafter) anodes, major anode degradation mechanism is attributed to the agglomeration of Ni phase, especially during the initial operation period (<200 hours). It has been reported that this initial agglomeration is associated with the initial fast sintering kinetics of Ni. [3][4][5][6][7][8][9][10][11][12] Ni sintering results in the reduction of active three phase boundary (TPB, hereafter) density and Ni network connectivity.The sintering mechanism depend on many process factors, such as, sintering temperature, fuel humidity and contaminants. [13][14][15][16] A few investigations were conducted to investigate the influence of reduction temperature on the pure initial Ni particle microstructure. Plascencia and Utigard 17 and Utigard et al. 18 have studied the reduction process of NiO particles at different temperatures. It is shown that different initial reduction temperatures lead to totally different morphologies of Ni particles in millimeter-scale. Thus, for conventional composite anode, the corresponding initial performance and durability can be also influenced by the Ni morphological differences created during the reduction process. Several researchers have reported on the influence of reduction temperature on the initial Ni-YSZ mi...

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Reduction kinetics of Goro nickel oxide using hydrogen

Cited by 101 publications

References 16 publications

Nickel catalyst auto-reduction during steam reforming of bio-oil model compound acetic acid

Nickel catalyst auto-reduction during steam reforming of bio-oil model compound acetic acid

Numerical Modeling of Oxygen Carrier Performances (NiO/NiAl2O4) for Chemical-Looping Combustion

Quantitative Study on the Correlation between Solid Oxide Fuel Cell Ni-YSZ Composite Anode Performance and Reduction Temperature Based on Three-Dimensional Reconstruction

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