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Mapping the Pore Architecture of Structured Catalyst Monoliths from Nanometer to Centimeter Scale with Electron and X-ray Tomographies

Becher, Johannes ; Sheppard, Thomas L. ; Fam, Yakub ; Baier, Sina ; Wang, Wu ; Wang, Di ; Kulkarni, Satishkumar ; Keller, Thomas F. ; Lyubomirskiy, Mikhail and Brueckner, Dennis , et al. (2019) In Journal of Physical Chemistry C
Abstract

The hierarchical pore systems of Pt/Al2O3 exhaust gas aftertreatment catalysts were analyzed with a collection of correlative imaging techniques to monitor changes induced by hydrothermal aging. Synergistic imaging with laboratory X-ray microtomography, synchrotron radiation ptychographic X-ray computed nanotomography, and electron tomography allowed quantitative observation of the catalyst pore architecture from centimeter to nanometer scale. Thermal aging at 750 °C in air and hydrothermal aging at 1050 °C in 10% H2O/air caused increasing structural degradation, which manifested as widespread sintering of Pt particles, increased volume and quantity of macropores (>20 nm), and reduction in effective... (More)

The hierarchical pore systems of Pt/Al2O3 exhaust gas aftertreatment catalysts were analyzed with a collection of correlative imaging techniques to monitor changes induced by hydrothermal aging. Synergistic imaging with laboratory X-ray microtomography, synchrotron radiation ptychographic X-ray computed nanotomography, and electron tomography allowed quantitative observation of the catalyst pore architecture from centimeter to nanometer scale. Thermal aging at 750 °C in air and hydrothermal aging at 1050 °C in 10% H2O/air caused increasing structural degradation, which manifested as widespread sintering of Pt particles, increased volume and quantity of macropores (>20 nm), and reduction in effective surface area coupled with decreasing volume and frequency of mesopores (2-20 nm) and micropores (<2 nm). Electron tomography unraveled the three-dimensional (3D) structure with high resolution allowing visualization of meso- and macropores but with samples of maximum 300 nm thickness. To complement this, hard X-ray ptychographic tomography produced quantitative 3D electron density maps of 5 μm diameter samples with spatial resolution <50 nm, effectively filling the resolution gap between electron tomography and hard X-ray microtomography. The obtained 3D volumes are an essential input for future computational modeling of fluid dynamics, mass transport, or diffusion properties and may readily complement bulk one-dimensional porosimetry measurements or simulated porosity.

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Contribution to journal
publication status
published
in
Journal of Physical Chemistry C
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85073247464
ISSN
1932-7447
DOI
10.1021/acs.jpcc.9b06541
language
English
LU publication?
no
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d3fa5001-9bc0-4156-a7bd-e09b9052fd23
date added to LUP
2019-10-26 12:46:54
date last changed
2020-12-29 02:24:47
@article{d3fa5001-9bc0-4156-a7bd-e09b9052fd23,
  abstract     = {<p>The hierarchical pore systems of Pt/Al<sub>2</sub>O<sub>3</sub> exhaust gas aftertreatment catalysts were analyzed with a collection of correlative imaging techniques to monitor changes induced by hydrothermal aging. Synergistic imaging with laboratory X-ray microtomography, synchrotron radiation ptychographic X-ray computed nanotomography, and electron tomography allowed quantitative observation of the catalyst pore architecture from centimeter to nanometer scale. Thermal aging at 750 °C in air and hydrothermal aging at 1050 °C in 10% H<sub>2</sub>O/air caused increasing structural degradation, which manifested as widespread sintering of Pt particles, increased volume and quantity of macropores (&gt;20 nm), and reduction in effective surface area coupled with decreasing volume and frequency of mesopores (2-20 nm) and micropores (&lt;2 nm). Electron tomography unraveled the three-dimensional (3D) structure with high resolution allowing visualization of meso- and macropores but with samples of maximum 300 nm thickness. To complement this, hard X-ray ptychographic tomography produced quantitative 3D electron density maps of 5 μm diameter samples with spatial resolution &lt;50 nm, effectively filling the resolution gap between electron tomography and hard X-ray microtomography. The obtained 3D volumes are an essential input for future computational modeling of fluid dynamics, mass transport, or diffusion properties and may readily complement bulk one-dimensional porosimetry measurements or simulated porosity.</p>},
  author       = {Becher, Johannes and Sheppard, Thomas L. and Fam, Yakub and Baier, Sina and Wang, Wu and Wang, Di and Kulkarni, Satishkumar and Keller, Thomas F. and Lyubomirskiy, Mikhail and Brueckner, Dennis and Kahnt, Maik and Schropp, Andreas and Schroer, Christian G. and Grunwaldt, Jan Dierk},
  issn         = {1932-7447},
  language     = {eng},
  month        = {01},
  publisher    = {The American Chemical Society (ACS)},
  series       = {Journal of Physical Chemistry C},
  title        = {Mapping the Pore Architecture of Structured Catalyst Monoliths from Nanometer to Centimeter Scale with Electron and X-ray Tomographies},
  url          = {http://dx.doi.org/10.1021/acs.jpcc.9b06541},
  doi          = {10.1021/acs.jpcc.9b06541},
  year         = {2019},
}