Mechanism of grain reconstruction of Pd and Pd/Ni wires during Pt–catchment

Fjellvåg, Asbjørn Slagtern; Jørgensen, Peter Stanley; Waller, David; Wragg, David S.; Michiel, Marco Di; Sjåstad, Anja Olafsen

doi:10.1016/j.mtla.2022.101359

Cited by 4 publications

(39 citation statements)

References 39 publications

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“…%. This stands in contrast to reports on Pd, 4 which show a significantly lower Pt content after Pt-catchment experiments on quasi-monocrystalline wires (Table 3). Notably, both mass changes and ICP−OES indicate that all quasi-monocrystalline Pd/Au samples show improved Pt-catchment compared to quasi-monocrystalline Pd.…”

Section: Quasi-monocrystalline (Preannealed) Pd/au Alloyscontrasting

confidence: 99%

“…% Pt after 20 days, according to the ICP−OES analysis. However, compared to Pd treated for 10 days by Fjellvag et al, 4 the Pt content (at. %) is lower in the Pd/ Au samples.…”

Section: Analysis Of Grain Structure Prior To Experimentsmentioning

confidence: 90%

“…MATLAB 36 was used for diffusion simulations, relying on the diffusion model developed by Fjellvag et al 4 using estimated diffusion coefficients for the two mixed Pd/Au compositions (Table S4).…”

Section: Methodsmentioning

confidence: 99%

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Pt-Catchment Using Pd/Au Alloys: Effect of Enhanced Diffusion

Fjellvåg

Waller

et al. 2023

Ind. Eng. Chem. Res.

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We have studied a series of Pd/Au alloys as Pt-catchment materials, both in lab-scale experiments and in an industrial ammonia oxidation plant. Our focus has been on how bulk Pt diffusion affects grain reconstruction in Pd/Au alloys (91/9 and 50/50 at. %) during Pt-catchment, performed by studying both polycrystalline (as produced) and quasi-monocrystalline (preannealed in vacuum) wires. The grain reconstruction is reduced when alloying Pd with Au, and it is almost absent for Pd/Au (50/50 at. %). For all Pd-containing samples with a quasi-monocrystalline grain structure, the restructuring is limited in short (<20 days) laboratory experiments but present in the 5 month industrial experiment. Notably, the Pd/Au (50/50 at. %) alloy shows a low degree of restructuring in all experiments but a reduced Pt-catchment in the industrial experiment. The mechanism for grain reconstruction of Pd/Au alloys is discussed, along with the role of the Kirkendall effect and the internal porosity on wire restructuring.

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Section: Quasi-monocrystalline (Preannealed) Pd/au Alloyscontrasting

confidence: 99%

“…% Pt after 20 days, according to the ICP−OES analysis. However, compared to Pd treated for 10 days by Fjellvag et al, 4 the Pt content (at. %) is lower in the Pd/ Au samples.…”

Section: Analysis Of Grain Structure Prior To Experimentsmentioning

confidence: 90%

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Pt-Catchment Using Pd/Au Alloys: Effect of Enhanced Diffusion

Fjellvåg

Waller

et al. 2023

Ind. Eng. Chem. Res.

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“…A recent study by Fjellvåg et al used in situ m-XCT to study grain reconstruction of Pd and Pd/Ni wires used during NH 3 oxidation for synthesis of nitric acid [92]. This reaction is topical in terms of sustainability as it involves significant loss of noble metal during operation.…”

Section: In Situ Tomography Of Catalysts Undermentioning

confidence: 99%

“…In situ µ‐XCT of morphological changes and chemical dynamics of Pd and Pd/Ni (91.3/8.7 at %) wires during experiments in synthetic air at 1273 K. Reprinted from 92, with permission from Elsevier. Copyright © 2022 Elsevier.…”

Section: In Situ and Operando Hard X‐ray Tomography Of Catalysts At Workmentioning

confidence: 99%

New Dimensions in Catalysis Research with Hard X‐Ray Tomography

Das

Pashminehazar

Sharma

et al. 2022

Chemie Ingenieur Technik

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The structure and function of solid catalysts are inseparably linked at length scales from nm to cm and beyond. Hard X-ray tomography offers unique potential for spatially-resolved characterization by combining flexible spatial resolution with a range of chemical contrasts. However, the full capabilities of hard X-ray tomography have not been widely explored in the catalysis community. This review highlights modern advances in hard X-ray tomography using synchrotron radiation. Case studies from model to technical scale illustrate the bright future of X-ray tomography in catalysis research.

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Challenges in quantifying Pt concentrations in Pd alloys by using secondary ion mass spectrometry: Strong grain orientation effects

Holme,

Håkonsen,

Waller

2024

Surface & Interface Analysis

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Palladium–platinum alloys were analysed by dynamic secondary ion mass spectrometry (SIMS) to investigate grain orientation effects that gave differences of up to 400% in the Pt/Pd count rate ratios, even within the same grain upon small rotations of a Pd sample with 1 wt% Pt. The sample had been homogenized by annealing, and the homogeneity was confirmed by X‐ray analysis in scanning electron microscopy (SEM). Grain orientations were determined by electron backscatter diffraction (EBSD). Crater depths were measured by white light interferometry (WLI). SEM images from the bottom of SIMS craters made in the same grain after small rotations around the sample surface normally showed different patterns of microfaceting for some rotation angles, probably exposing low‐index crystallographic planes. A complete understanding of the observed grain orientation effect is still lacking. However, factors such as ion mass, sputter rate, ion channelling, ion focusing, preferential sputtering, surface height, crater microfaceting and/or angle‐dependent sputtering seem to play a role. For these Pd–Pt alloys, the strong grain orientation effect adds another level of complexity when attempting to quantify concentrations and obtain depth profiles by SIMS. Without proper sampling and/or averaging, one could reach very wrong conclusions when comparing results from different samples.

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Mechanism of grain reconstruction of Pd and Pd/Ni wires during Pt–catchment

Cited by 4 publications

References 39 publications

Pt-Catchment Using Pd/Au Alloys: Effect of Enhanced Diffusion

Pt-Catchment Using Pd/Au Alloys: Effect of Enhanced Diffusion

New Dimensions in Catalysis Research with Hard X‐Ray Tomography

Challenges in quantifying Pt concentrations in Pd alloys by using secondary ion mass spectrometry: Strong grain orientation effects

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