Mathematical simulation of self-oscillations in methane oxidation on nickel: An isothermal model

Lashina, Elena A.; Каичев, В. В.; Чумакова, Н. А.; Ustyugov, V. V.; Chumakov, G. A.; Bukhtiyarov, Valerii I.

doi:10.1134/s0023158412030081

Cited by 15 publications

(14 citation statements)

References 47 publications

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“…At elevated pressures, the self-sustained rate oscillations in catalytic oxidation reactions over transition metals are more probably to follow the redox mechanism based on the reversible bulk oxidation of the catalyst. In full agreement with this hypothesis, the mathematic modeling of the oxidation of methane over nickel confirmed that the rate oscillations can arise because of the periodic oxidation and reduction of nickel [62] and that metallic nickel in this reaction is more active than NiO.…”

Section: Discussionsupporting

confidence: 62%

Evolution of self-sustained kinetic oscillations in the catalytic oxidation of propane over a nickel foil

Каичев

Teschner

Saraev

et al. 2016

Journal of Catalysis

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The evolution of self-sustained reaction-rate oscillations in the catalytic oxidation of propane over a nickel foil has been studied in situ using X-ray photoelectron spectroscopy coupled with on line mass spectrometry and gas chromatography. Changes in the effective surface area and in the catalyst morphology under reaction conditions have been examined by scanning electron microscopy and a krypton adsorption technique. It is shown that the regular kinetic oscillations arise under oxygen-lean conditions. CO, CO 2 , H 2 , H 2 O, and propylene are detected as products.The conversion of propane oscillates in a range from 1% to 23%. During the half-periods with high activity, the main reaction pathway is the partial oxidation of propane: selectivity toward CO achieves 98%. In contrast, during the half-periods with low activity, the reaction proceeds through three competitive pathways: the partial oxidation of propane, the total oxidation of propane, and the dehydrogenation of propane to propylene. The driving force for the selfsustained kinetic oscillations is the periodic reoxidation of nickel. According to the Ni2p and O1s core-level spectra measured in situ, the high-active catalyst surface is represented by metallic nickel, whereas during the inactive half-periods the catalyst surface is covered with a thick layer of NiO. The intensity of O1s spectra follows the oscillations of O 2 in the gas phase during the oxidation of propane. It is found that during the induction period before the regular oscillations appear, a rough and porous structure develops because of strong reconstruction of the catalyst surface. The thickness of the reconstructed layer is approximately 10-20 µm. This process is accompanied with at least an 80-fold increase in the effective surface area compared with a clean, non-treated nickel foil, which undoubtedly leads to a drastic increase in the number of active sites. We believe that it is the main reason for the induction period always being  Corresponding author.E-mail address: vvk@catalysis.ru (V.V. Kaichev) 2 observed before the appearance of self-sustained oscillations in the catalytic oxidation of light hydrocarbons over catalysts with a low specific surface area (single crystals, foils, or wires).Moreover, without such reconstruction, the oscillations cannot arise due to low activity of such catalysts.

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Section: Discussionsupporting

confidence: 62%

Evolution of self-sustained kinetic oscillations in the catalytic oxidation of propane over a nickel foil

Каичев

Teschner

Saraev

et al. 2016

Journal of Catalysis

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“…Similarly, when y CH4 is lowered to 0.47, the surface becomes saturated mainly with Ox and OH*. It corresponds to the non-reactive state in which the surface is oxidized (Lashina et al, 2012). However, this transition is continuous; therefore, it is second-order.…”

Section: Feed Concentration Of Methane (Y Ch 4 )mentioning

confidence: 99%

“…The effects of diffusion of adsorbed species, lattice coordination number and inactive impurities on the surface are also evaluated. Lashina et al (2012). According to these authors, the mechanism of CPOx can be described by an 18-step elementary reaction (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Partial oxidation of methane on a nickel catalyst: Kinetic Monte-Carlo simulation study

Pruksawan

Kitiyanan

Ziff

2016

Chemical Engineering Science

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Kinetic Monte-Carlo simulation is applied to study the partial oxidation of methane over a nickel catalyst. Based on the Langmuir-Hinshelwood mechanism, the kinetic behavior of this reaction is analyzed and the results are compared with previous experiments. This system exhibits kinetic phase transitions between reactive regions with sustained reaction and poisoned regions without reaction. The fractional coverages of the adsorbed species and the production rates of H 2 , CO, H 2 O, and CO 2 are evaluated at steady state as functions of feed concentration of the methane and oxygen, and reaction temperature. The influence of lattice coordination number, diffusion, and impurities on the surface is also investigated. The simulation results are in good agreement with the experimental studies where such results are available. It is observed that when the lattice coordination number is increased to eight, the width of the reactive region increases significantly. Moreover, the phase transition becomes continuous. The diffusion of adsorbed O and H on the surface plays a measurable role in the reaction, increasing the maximum production rates as the diffusion rate increases. In systems with impurities, the production rates are greatly reduced and the phase transition is also changed from being abrupt to continuous.

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“…with fast (x 2 ), intermediate (x 1 ), and slow (z) variables and small parameters µ and ε, the relaxation and mixed-mode oscillations and also chaotic dynamics were found [7,25,26]. Consider the one-parameter family of two-dimensional dynamical subsystems with the parameter ż…”

Section: Introductionmentioning

confidence: 99%

On estimation of the global error of numerical solution on canard-cycles

Chumakov

Lashina

Чумакова

2015

Mathematics and Computers in Simulation

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Mathematical simulation of self-oscillations in methane oxidation on nickel: An isothermal model

Cited by 15 publications

References 47 publications

Evolution of self-sustained kinetic oscillations in the catalytic oxidation of propane over a nickel foil

Evolution of self-sustained kinetic oscillations in the catalytic oxidation of propane over a nickel foil

Partial oxidation of methane on a nickel catalyst: Kinetic Monte-Carlo simulation study

On estimation of the global error of numerical solution on canard-cycles

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