Influence of oxide support on Pd properties: A gain for O diffusion versus minor impact for CH4 dissociation

Rybakov, Andrey A.; Bryukhanov, I. A.; Larin, A. V.; Todorova, S.; Vercauteren, Daniel P.; Zhidomirov, G. M.

doi:10.1016/j.cattod.2019.11.018

Cited by 4 publications

(18 citation statements)

References 64 publications

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“…The second 3L Pd slab (Figure S3b) was prepared from a 4L Pd slab deposited over Al 36 O 64 H 16 one ("grown" shown by bottom half-filled diamonds in Figure 9) using the method discussed in our previous work. 20 As we showed earlier, the intralayer Pd−Pd distance for the 4L slab on the Al 36 O 64 H 16 support converges to a shorter limit of 2.648 Å. 44 This value is not an exaggerated purely computational effect because even shorter Pd−Pd distances of 2.60 Å were measured in organic complexes of Pd NPs.…”

Section: Thementioning

confidence: 57%

“…For comparison, the critical squares of Pd 4 windows in the transition state (TS) geometry for O jumps through the second and third Pd(100) layers are calculated as 8.12 and 8.39 Å 2 , respectively. 20 3 and Figure 5). Thevenin et al 61 reported TPO results with maximum O 2 adsorption at around 300 °C for Pd/Al 2 O 3 .…”

Section: Technical Aspectsmentioning

confidence: 93%

“…19 Earlier, it was shown that various supports [(100)γ-Al 2 O 3 , anatase TiO 2 , and the tetragonal form of ZrO 2 ] can lead to different structures of metallic layers with various Pd−Pd distances in the layers. 20 The latter systematically change with distance from the Me/oxide contact zone and converge to the limits that depend on the support and do not coincide with the bulk Pd value of 2.756 Å. 21 As a result, the influence of the support is important for the O diffusion in Pd layers 20 The Pd(100) slabs on different supports 20 are an attractive object for studying ferromagnetism in Pd induced by a violation of local symmetry of atomic position or by lattice expansion also named as superparamagnetism.…”

Section: Introductionmentioning

confidence: 99%

“…20 The latter systematically change with distance from the Me/oxide contact zone and converge to the limits that depend on the support and do not coincide with the bulk Pd value of 2.756 Å. 21 As a result, the influence of the support is important for the O diffusion in Pd layers 20 The Pd(100) slabs on different supports 20 are an attractive object for studying ferromagnetism in Pd induced by a violation of local symmetry of atomic position or by lattice expansion also named as superparamagnetism. 6 The effect of support expansion was possibly first demonstrated for NPs of antiferromagnetic Fe deposited over Cu(001) with a larger unit cell.…”

Section: Introductionmentioning

confidence: 99%

“…Then, the CH 4 dissociation reaction can pass differently over the metal slab grown on each Me-spinel as it happens with O diffusion. 20 After the Technical Aspects section, we will compare the two possibilities in Sections 3.1 and 3.2, then the magnetic properties of the obtained slabs (Section 3.3) and their changes in the course of the reaction (Section 3.4) will be considered.…”

Section: Introductionmentioning

confidence: 99%

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Spatial and Magnetic Factors for CH₄ Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al₂O₃ Support or MeAl₂O₄ Spinels, Me = Ni, Co, Mn

Rybakov

Bryukhanov

Todorova³

et al. 2019

J. Phys. Chem. C

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Two variants of the introduction of transition metals (TMs) Me = Ni, Mn, Co into the Pd(100)/(100)γ-Al2O3 catalytic system are presented to reveal a possible influence of TM on the catalytic activity of Pd for CH4 dissociation. Al/Me replacement at the (100)γ-Al2O3 surface is performed at the normal (four-coordinated) or undercoordinated (two-coordinated) Al positions, on the one hand. MeAl2O4 spinel formation is admitted at a stoichiometric Me/Al ratio, on the other hand. The addition of TM to the (100)γ-Al2O3 slab weakly changes the activation energy of CH4 dissociation. The dissociation barrier is higher for the Pd deposited over (100)MeAl2O4 spinels than the barriers over Pd(100)/(100)γ-Al2O3 catalysts. The dissociation barrier grows with a MeAl2O4 cell parameter from Ni to Mn. The minimum barrier over different supports (ZrO2, Al2O3, MeAl2O4) was found for Pd(100) deposited on the defective (100)γ-Al2O3 model. Considering another step of the whole Pd/PdO redox cycle of CH4 oxidation, we evaluated the consequences of large Pd···Pd distances over MeAl2O4 for atomic O diffusion in Pd(100). Higher squares of Pd4 windows, which limit the O jumps, relative to those calculated for transition states in Pd(100)/(100)γ-Al2O3 predict an easier O diffusion in Pd/MeAl2O4. The O2 consumption at lower temperatures in the spinels was tested experimentally using temperature-programmed oxidation (TPO) method and confirmed the easier O2 chemisorption therein compared to Pd(100)/(100)γ-Al2O3. Magnetic TM moments reveal weak changes in the course of CH4 dissociation for both routes of TM addition mainly depending on reordering of Pd geometry and its magnetic moments at both (100)γ-Al2O3 or (100)MeAl2O4.

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Section: Thementioning

confidence: 57%

Section: Technical Aspectsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatial and Magnetic Factors for CH₄ Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al₂O₃ Support or MeAl₂O₄ Spinels, Me = Ni, Co, Mn

Rybakov

Bryukhanov

Todorova³

et al. 2019

J. Phys. Chem. C

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Partial Palladium Oxidation over Various Oxide Supports for a Higher Reactivity of PdO with Respect to CH₄

et al. 2022

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A series of PdO slabs deposited via low-index planes (100), (010), (001), and (101) on γ-alumina, titania, and zirconia was modeled. Relative stabilities and surface energies of the PdO planes are divided into two groups of (100), on the one hand, and (010), (001), and (101), on the other hand. The calculated barriers of CH4 dissociation increase with the stability or decreases versus surface energies of joined system being the lowest for the 4-layer PdO(010) without support and over monoclinic ZrO2. The authors outline that CH4 oxidation upon a partial transformation of Pd to PdO allows growing of more active PdO planes (in the terms of activation barrier) over Pd instead of the most stable (in the terms of stabilization energy ΔU 1 or surface energy γ) and less active PdO(100) at the oxide supports (γ-Al2O3, ZrO2, TiO2). The role of the contact Pd/support layer in PdO formation is discussed. Computed barriers of CH4 dissociation related to separate PdO planes over the oxides are compared with oxidation barriers calculated or measured in other works.

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Translational dependence of the geometry of metallic mono- and bilayers optimized on semi-ionic supports: the cases of Pd on γ-Al₂O₃(110), monoclinic ZrO₂(001), and rutile TiO₂(001)

Rybakov

Larin²,

Trubnikov

et al. 2022

CrystEngComm

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Influence of oxide support on Pd properties: A gain for O diffusion versus minor impact for CH4 dissociation

Cited by 4 publications

References 64 publications

Spatial and Magnetic Factors for CH₄ Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al₂O₃ Support or MeAl₂O₄ Spinels, Me = Ni, Co, Mn

Spatial and Magnetic Factors for CH₄ Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al₂O₃ Support or MeAl₂O₄ Spinels, Me = Ni, Co, Mn

Partial Palladium Oxidation over Various Oxide Supports for a Higher Reactivity of PdO with Respect to CH₄

Translational dependence of the geometry of metallic mono- and bilayers optimized on semi-ionic supports: the cases of Pd on γ-Al₂O₃(110), monoclinic ZrO₂(001), and rutile TiO₂(001)

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Influence of oxide support on Pd properties: A gain for O diffusion versus minor impact for CH4 dissociation

Cited by 4 publications

References 64 publications

Spatial and Magnetic Factors for CH4 Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al2O3 Support or MeAl2O4 Spinels, Me = Ni, Co, Mn

Spatial and Magnetic Factors for CH4 Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al2O3 Support or MeAl2O4 Spinels, Me = Ni, Co, Mn

Partial Palladium Oxidation over Various Oxide Supports for a Higher Reactivity of PdO with Respect to CH4

Translational dependence of the geometry of metallic mono- and bilayers optimized on semi-ionic supports: the cases of Pd on γ-Al2O3(110), monoclinic ZrO2(001), and rutile TiO2(001)

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Spatial and Magnetic Factors for CH₄ Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al₂O₃ Support or MeAl₂O₄ Spinels, Me = Ni, Co, Mn

Spatial and Magnetic Factors for CH₄ Oxidation on Pd Slabs in the Presence of Transition-Metal Me Cations Exchanged in γ-Al₂O₃ Support or MeAl₂O₄ Spinels, Me = Ni, Co, Mn

Partial Palladium Oxidation over Various Oxide Supports for a Higher Reactivity of PdO with Respect to CH₄

Translational dependence of the geometry of metallic mono- and bilayers optimized on semi-ionic supports: the cases of Pd on γ-Al₂O₃(110), monoclinic ZrO₂(001), and rutile TiO₂(001)