dc.contributor.advisor Farooq, Aamir dc.contributor.author Slama de Freitas, Ana Luiza dc.date.accessioned 2021-12-01T13:09:16Z dc.date.available 2021-12-01T13:09:16Z dc.date.issued 2021-11 dc.identifier.citation Slama De Freitas, A. L. (2021). Investigation of Shock Wave Effects on Phase Transformation and Structural Modification of TiO$_2$ and Al$_2$O$_3$. KAUST Research Repository. https://doi.org/10.25781/KAUST-2H12P dc.identifier.doi 10.25781/KAUST-2H12P dc.identifier.uri http://hdl.handle.net/10754/673875 dc.description.abstract Titanium dioxide and aluminum oxide are conventional materials used in heterogeneous catalysis as catalyst support. The widely used crystalline phase of both supports is the metastable phase (anatase and γ-Al$_2$O$_3$) in which they possess a higher specific surface area compared to the thermodynamically stable phase (rutile and α-Al$_2$O$_3$). However, these phases have better thermal and mechanical stability than anatase and γ-Al$_2$O$_3$. A novel method to induce phase transformation and structural modification of crystalline materials is by applying shock waves. This study aims to experimentally investigate the effects of shock wave treatment on titania and alumina. A pressure-driven shock tube was used in this work to generate the shock waves. Two sets of experiments were carried out for TiO$_2$ and one for Al$_2$O$_3$. Titania samples were prepared in the form of pellets for the first set. Titania and alumina samples were maintained as powder for the second set of experiments. For titania, twenty shocks were applied at nominal temperature and pressure of ~ 1772 K and 23.3 bar in the first set of experiments, while thirty shocks of ~ 1572 K and 66 bar were applied in the second set of experiments. For alumina, twenty shock loadings were applied at the same conditions used for the second set of titania. Characterization techniques, such as XRD, Raman spectroscopy, TEM, SEM, XPS, and N$_2$ physisorption were employed on treated samples in order to understand the effects of shock wave treatment. Partial phase transformation was observed in shock treated TiO2 from Raman spectra and TEM images. Crystallite size reduction was observed in the first set of experiments, while increase in defects was observed by the enhanced Ti$^{+3}$ in XPS spectra in both sets of experiments. Partial phase transformation was also observed in shock treated Al$_2$O$_3$, when mixed with CNF (carbon nanofibers), from XRD patterns and confirmed with XPS. For alumina, TEM and SEM images showed the smallest particles in contact with carbon fibers, while the biggest particles exhibited agglomeration. Physisorption experiments showed a decrease of 40% in surface area and pore collapse. dc.language.iso en dc.subject Shockwave dc.subject Titania dc.subject Alumina dc.subject modification dc.subject Shock tube dc.subject Phase transformation dc.title Investigation of Shock Wave Effects on Phase Transformation and Structural Modification of TiO$_2$ and Al$_2$O$_3$ dc.type Thesis dc.contributor.department Physical Science and Engineering (PSE) Division dc.rights.embargodate 2022-12-01 thesis.degree.grantor King Abdullah University of Science and Technology dc.contributor.committeemember Gascon, Jorge dc.contributor.committeemember Ruiz-Martinez, Javier thesis.degree.discipline Chemical Engineering thesis.degree.name Master of Science dc.rights.accessrights At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis will become available to the public after the expiration of the embargo on 2022-12-01. refterms.dateFOA 2021-12-01T13:09:17Z kaust.request.doi yes
﻿

### Files in this item

Name:
2nd version_Thesis - Ana Luiza.pdf
Size:
3.495Mb
Format:
PDF
Description:
Ana Luiza Slama de Freitas - Final Paper
Embargo End Date:
2022-12-01