Particle Size Effect on CH4 Oxidation Over Noble Metals: Comparison of Pt and Pd Catalysts

Stakheev, A. Yu.; Batkin, A. M.; Teleguina, N. S.; Брагина, Г. О.; Zaikovsky, V. I.; Prosvirin, Igor P.; Khudorozhkov, Alexander K.; Bukhtiyarov, Valerii I.

doi:10.1007/s11244-013-9971-y

Cited by 81 publications

(57 citation statements)

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“…[15] Recently,for efficient removal of unburned methane, catalysts for the complete combustion of methane have been extensively developed. [25] Thesame trend has also been reported by Hicks [26,27] Baldwin and Burch reported that the activity of Pd/Al 2 O 3 largely varied with Pd particle size,but no correlation was found between the Pd particle size and the TOF. [15][16][17][18][19][20][21][22][23] However, the activity of conventional Pd catalysts is still insufficient, and the enhancement of catalytic activity is demanded, in particular,a tl ower temperatures (< 300 8 8C).…”

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confidence: 56%

“…[15] Figure 1b shows the dependence of TOFo nP dp article size for Pd/Al 2 O 3 having various alumina crystalline phases. [25] Comparing catalysts having different alumina crystalline phases,the TOFs of Pd/q-Al 2 O 3 and Pd/a-Al 2 O 3 were higher than those of Pd/g-Al 2 O 3 in all Pd particle size regions.M ore specifically,t he TOFof 7.3 nm Pd/q-Al 2 O 3 was more than seven times higher than Pd/ g-Al 2 O 3 .The size dependencyofTOF was also obtained using Pd/Al 2 O 3 catalysts without H 2 pretreatment (Supporting Information, Figure S9). Interestingly,the TOFs of Pd/q-Al 2 O 3 and Pd/a-Al 2 O 3 showed av olcano-shaped dependence on the size of Pd particles.T he TOFs drastically increased from 0.040 to 0.621 s À1 as Pd particle size increased from 1.5 to 7.3 nm, but they gradually decreased to 0.271 s À1 with Pd particle size increasing to 19 nm.…”

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The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al₂O₃ on Methane Combustion

et al. 2017

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The particle size effect of Pd nanoparticles supported on alumina with various crystalline phases on methane combustion was investigated. Pd/θ, α-Al O with weak metal-support interaction showed a volcano-shaped dependence of the catalytic activity on the size of Pd particles, and the catalytic activity of the strongly interacted Pd/γ-Al O increased with the particle size. Based on a structural analysis of Pd nanoparticles using CO adsorption IR spectroscopy and spherical aberration-corrected scanning/transmission electron microscopy, the dependence of catalytic activity on Pd particle size and the alumina crystalline phase was due to the fraction of step sites on Pd particle surface. The difference in fraction of the step site is derived from the particle shape, which varies not only with Pd particle size but also with the strength of metal-support interaction. Therefore, this interaction perturbs the particle size effect of Pd/Al O for methane combustion.

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The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al₂O₃ on Methane Combustion

et al. 2017

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“…It should be noted that some reactions indeed can proceed via both the LangmuirHinshelwood and the Mars-van Krevelen mechanisms depending on experimental conditions and a catalyst type [65][66][67][68]. For instance, the oxidation of methane over Pt-based catalysts proceeds via the Langmuir-Hinshelwood mechanism, whereas over Pd-based catalysts, the oxidation of methane proceeds via the Mars-van Krevelen mechanism under the same experimental conditions [65].…”

Section: Discussionmentioning

confidence: 98%

“…For instance, the oxidation of methane over Pt-based catalysts proceeds via the Langmuir-Hinshelwood mechanism, whereas over Pd-based catalysts, the oxidation of methane proceeds via the Mars-van Krevelen mechanism under the same experimental conditions [65]. In the first case, platinum is mainly in the metallic state, while in the second case, small PdO particles form over the catalyst surface.…”

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confidence: 99%

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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“…Stakheev et al [24] studied the particle size effect of Pd on the activity of Pd/Al 2 O 3 for CH 4 oxidation and revealed that the intrinsic activity expressed as TOF linearly increased with an increase in Pd particle size from 1 to 20 nm. They explained this dependency by the consideration that CH 4 oxidation follows Mars-van Krevelen mechanism over the surface of Pd oxide particles and the enhancement of intrinsic activity with increasing Pd particle size is, presumably, associated with decreased Pd O bond strength for larger particles.…”

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confidence: 99%

Effect of Pd dispersion on the catalytic activity of Pd/Al2O3 for C3H6 and CO oxidation

et al. 2017

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Particle Size Effect on CH4 Oxidation Over Noble Metals: Comparison of Pt and Pd Catalysts

Cited by 81 publications

References 20 publications

The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al₂O₃ on Methane Combustion

The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al₂O₃ on Methane Combustion

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

Effect of Pd dispersion on the catalytic activity of Pd/Al2O3 for C3H6 and CO oxidation

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Particle Size Effect on CH4 Oxidation Over Noble Metals: Comparison of Pt and Pd Catalysts

Cited by 81 publications

References 20 publications

The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al2O3 on Methane Combustion

The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al2O3 on Methane Combustion

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

Effect of Pd dispersion on the catalytic activity of Pd/Al2O3 for C3H6 and CO oxidation

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The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al₂O₃ on Methane Combustion

The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al₂O₃ on Methane Combustion