Alignment methods for nanotomography with deep subpixel accuracy

Odstrčil, Michal; Holler, Mirko; Raabe, Jörg; Guizar‐Sicairos, Manuel

doi:10.1364/oe.27.036637

Cited by 44 publications

(35 citation statements)

References 56 publications

(111 reference statements)

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“…For original tomogram, see Supplementary Materials Figure S4. The reconstructed tomogram had a voxel size of 38.1 nm and an effective spatial resolution of 78.3 nm, estimated by Fourier shell correlation (FSC) as implemented in the reconstruction script of Odstrčil et al [46]. The selected region and the associated FSC are shown in the Supplementary Materials Figure S5 and Figure S6, respectively.…”

Section: Tomography Studiesmentioning

confidence: 99%

“…The total acquisition of the tomogram took about 19 h. Ptychographic reconstructions were done on a cropped area of 256 × 256 pixels, corresponding to a pixel size of 37 nm, with the PtyREX package [69] to obtain a 2D projection series. This series was aligned and reconstructed into 3D volumes with a reconstructed voxel size of 38.1 nm and effective isotropic resolution of 78.3 nm using the MATLAB script by Odstrcil et al [46].…”

Section: Tomography Studiesmentioning

confidence: 99%

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Porosity and Structure of Hierarchically Porous Ni/Al2O3 Catalysts for CO2 Methanation

et al. 2020

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CO2 methanation is often performed on Ni/Al2O3 catalysts, which can suffer from mass transport limitations and, therefore, decreased efficiency. Here we show the application of a hierarchically porous Ni/Al2O3 catalyst for methanation of CO2. The material has a well-defined and connected meso- and macropore structure with a total porosity of 78%. The pore structure was thoroughly studied with conventional methods, i.e., N2 sorption, Hg porosimetry, and He pycnometry, and advanced imaging techniques, i.e., electron tomography and ptychographic X-ray computed tomography. Tomography can quantify the pore system in a manner that is not possible using conventional porosimetry. Macrokinetic simulations were performed based on the measures obtained by porosity analysis. These show the potential benefit of enhanced mass-transfer properties of the hierarchical pore system compared to a pure mesoporous catalyst at industrially relevant conditions. Besides the investigation of the pore system, the catalyst was studied by Rietveld refinement, diffuse reflectance ultraviolet-visible (DRUV/vis) spectroscopy, and H2-temperature programmed reduction (TPR), showing a high reduction temperature required for activation due to structural incorporation of Ni into the transition alumina. The reduced hierarchically porous Ni/Al2O3 catalyst is highly active in CO2 methanation, showing comparable conversion and selectivity for CH4 to an industrial reference catalyst.

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Section: Tomography Studiesmentioning

confidence: 99%

Section: Tomography Studiesmentioning

confidence: 99%

Porosity and Structure of Hierarchically Porous Ni/Al2O3 Catalysts for CO2 Methanation

et al. 2020

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“…The tomograms were aligned and reconstructed using the script of Odstrčil et al. [36] with a resulting voxel size of ca. 37 nm for all samples.…”

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confidence: 99%

Hard X‐Ray Nanotomography for 3D Analysis of Coking in Nickel‐Based Catalysts

et al. 2021

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Understanding catalyst deactivation by coking is crucial for knowledge‐based catalyst and process design in reactions with carbonaceous species. Post‐mortem analysis of catalyst coking is often performed by bulk characterization methods. Here, hard X‐ray ptychographic computed tomography (PXCT) was used to study Ni/Al2O3 catalysts for CO2 methanation and CH4 dry reforming after artificial coking treatment. PXCT generated quantitative 3D maps of local electron density at ca. 80 nm resolution, allowing to visualize and evaluate the severity of coking in entire catalyst particles of ca. 40 μm diameter. Coking was primarily revealed in the nanoporous solid, which was not detectable in resolved macropores. Coke formation was independently confirmed by operando Raman spectroscopy. PXCT is highlighted as an emerging characterization tool for nanoscale identification, co‐localization, and potentially quantification of deactivation phenomena in 3D space within entire catalyst particles.

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“…As the pixel size of projections depends on the x-ray photon energy, we resized all complex-valued ptychographic projections to a common pixel size of 26.52 nm using an interpolation based on fast fractional Fourier transform ( 58 , 59 ). Next, the phase of the reconstructed 2D projections was extracted by post-processing alignment and removal of constant and linear phase components, and the projections were aligned using a tomographic consistency approach ( 59 ).…”

Section: Methodsmentioning

confidence: 99%

Sparse ab initio x-ray transmission spectrotomography for nanoscopic compositional analysis of functional materials

et al. 2021

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The performance of functional materials is either driven or limited by nanoscopic heterogeneities distributed throughout the material’s volume. To better our understanding of these materials, we need characterization tools that allow us to determine the nature and distribution of these heterogeneities in their native geometry in 3D. Here, we introduce a method based on x-ray near-edge spectroscopy, ptychographic x-ray computed nanotomography, and sparsity techniques. The method allows the acquisition of quantitative multimodal tomograms of representative sample volumes at sub–30 nm half-period spatial resolution within practical acquisition times, which enables local structure refinements in complex geometries. To demonstrate the method’s capabilities, we investigated the transformation of vanadium phosphorus oxide catalysts with industrial use. We observe changes from the micrometer to the atomic level and the formation of a location-specific defect so far only theorized. These results led to a reevaluation of these catalysts used in the production of plastics.

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Alignment methods for nanotomography with deep subpixel accuracy

Cited by 44 publications

References 56 publications

Porosity and Structure of Hierarchically Porous Ni/Al2O3 Catalysts for CO2 Methanation

Porosity and Structure of Hierarchically Porous Ni/Al2O3 Catalysts for CO2 Methanation

Hard X‐Ray Nanotomography for 3D Analysis of Coking in Nickel‐Based Catalysts

Sparse ab initio x-ray transmission spectrotomography for nanoscopic compositional analysis of functional materials

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