Glowska, Aleksandra Dominika;
(2022)
Multi-technique analysis of pore networks in gamma-alumina catalyst supports.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
In this thesis, a multi-technique strategy was developed for characterisation of gamma-alumina catalyst supports. A range of techniques was employed to enable a complex analysis of their porous structure and gain better understanding of its impact on mass transfer properties. The strategy was implemented on gamma-alumina supports with very different diffusional properties. The developed strategy combined classical characterisation techniques used for porous solids and diffusion measurements. To examine the diffusion inside the gamma-alumina pore network, PFG (Pulsed Field Gradient)-NMR experiments were performed and based on these experiments, the diffusional tortuosity factor was determined. The characterisation of the porous structure involved the use of N2 adsorption/desorption experiments (including scanning isotherm experiments), mercury porosimetry, NMR relaxometry, spatially resolved SAXS (small-angle Xray scattering), TEM (transmission) and SEM (scanning electron microscopy) imaging. These techniques allowed to evaluate the pore network properties relevant for mass transfer and gave insight in the pore network topology. SEM imaging allowed to propose a model of gamma-alumina spatial organisation in the form of alumina inclusions embedded in an alumina matrix. This led to the development of advanced image processing approaches, including deep learning semantic segmentation and porosity measurement under grey-level calibration, which enabled to quantify the inclusions and porosity differences between the latter and the alumina matrix, being the key parameters that served as input for mass transfer predictions. Finally, evidence for surface barriers to molecular transport, associated to the interfaces between the inclusions and the matrix, were discovered and evaluated for the first time in alumina. The impact of surface barriers increased with increasing inclusion content quantified by image processing. Further proof for the impact of suspected surface barriers on catalysis was obtained by analysing the activity of alumina-supported catalysts for hydrodenitrogenation of vacuum gas oil.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Multi-technique analysis of pore networks in gamma-alumina catalyst supports |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10162131 |
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