Abstract
A reliable quantitative analysis in electron tomography, which depends on the segmentation of the three-dimensional reconstruction, is challenging because of constraints during tilt-series acquisition (missing wedge) and reconstruction artifacts introduced by reconstruction algorithms such as the Simultaneous Iterative Reconstruction Technique (SIRT) and Discrete Algebraic Reconstruction Technique (DART). We have carefully evaluated the fidelity of segmented reconstructions analyzing a disordered mesoporous carbon used as support in catalysis. Using experimental scanning transmission electron microscopy (STEM) tomography data as well as realistic phantoms, we have quantitatively analyzed the effect on the morphological description as well as on diffusion properties (based on a random-walk particle-tracking simulation) to understand the role of porosity in catalysis. The morphological description of the pore structure can be obtained reliably both using SIRT and DART reconstructions even in the presence of a limited missing wedge. However, the measured pore volume is sensitive to the threshold settings, which are difficult to define globally for SIRT reconstructions. This leads to noticeable variations of the diffusion coefficients in the case of SIRT reconstructions, whereas DART reconstructions resulted in more reliable data. In addition, the anisotropy of the determined diffusion properties was evaluated, which was significant in the presence of a limited missing wedge for SIRT and strongly reduced for DART.
Highlights
Mesoporous materials have attracted a lot of attention and are of great importance in many advanced applications due to their remarkable properties, such as high specific surface area, versatile pore structure, chemical inertness, and good mechanical stability (Ryoo et al, 2001; Taguchi & Schüth, 2005; Liang et al, 2008)
A reliable quantitative analysis in electron tomography, which depends on the segmentation of the 3D reconstruction, is still challenging because of constraints during tilt-series acquisition and reconstruction artifacts introduced by established reconstruction algorithms such as Simultaneous Iterative Reconstruction Technique (SIRT) and Discrete Algebraic Reconstruction Technique (DART)
When looking closely at the highlighted regions, we found that the size and connectivity of some of the pores in the 2D slices is different in the two segmented results and does not necessarily fit to our visual interpretation of the SIRT reconstruction
Summary
Mesoporous materials have attracted a lot of attention and are of great importance in many advanced applications due to their remarkable properties, such as high specific surface area, versatile pore structure, chemical inertness, and good mechanical stability (Ryoo et al, 2001; Taguchi & Schüth, 2005; Liang et al, 2008). All aspects of the performance of supported catalysts (activity, selectivity and stability) are strongly influenced by the architecture of the porous support: i) the mesopores (2-50 nm) and micropores (
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