NOTE: This item is not available outside the Texas A&M University network. Texas A&M affiliated users who are off campus can access the item through NetID and password authentication or by using TAMU VPN. Non-affiliated individuals should request a copy through their local library's interlibrary loan service.
Synthesis and characterization of zirconia aerogels
| dc.creator | Khazi-Syed, Azghar H. | |
| dc.date.accessioned | 2012-06-07T22:36:56Z | |
| dc.date.available | 2012-06-07T22:36:56Z | |
| dc.date.created | 1994 | |
| dc.date.issued | 1994 | |
| dc.identifier.uri | https://hdl.handle.net/1969.1/ETD-TAMU-1994-THESIS-K456 | |
| dc.description | Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. | en |
| dc.description | Includes bibliographical references. | en |
| dc.description.abstract | Zirconia gels were prepared using zirconium n-propoxide, acetic acid and npropanol using the sol-gel process. Zirconium alkoxides are very moisture sensitive, but controlled hydrolysis was achieved through generation of water from the esterification reaction between acetic acid and n-propanol. The hydrolysis product then polymerizes through a fast condensation reaction to produce a gel. The wetgels were dried under supercritical conditions in an autoclave to yield aerogels. 'ne aerogels were characterized using BET nitrogen adsorption method, X-ray powder diffraction, Infrared Analysis and Simultaneous Thermal Analysis. The aerogels were sulfated and characterized using pyridine adsorption and NMR. Gelation times increased with increasing acetic acid content and also with increasing alcohol content. The gelation process was accelerated with increasing temperature and was found to obey the Arrhenius relation. The surface areas of the aerogels increased but pore sizes decreased with increasing alkoxide concentration. The differential thermal analysis curve was characterized by the appearance of three regions of change: ( i ) removal of the solvent and free water, ( i i ) removal of the residual organics and phase transformation from cubic to monoclinic form, and ( iii ) the reversible transformation between monoclinic and tetragonal phases. Fourier Transform Infrared Spectroscopy and X-ray powder diffraction studies confirmed the results from the thermal analysis. The BET nitrogen adsorption / desorption isotherms were studied to follow the changes in the pore shapes of the aerogels prepared under different conditions. Pyridine adsorption on sulfated aerogel showed peaks for Lewis acid sites, Br6nsted acid sites and a combination of both. The superacidity of sulfated zirconia is attributed to the presence of the combination of both types of the acid sites. | en |
| dc.format.medium | electronic | en |
| dc.format.mimetype | application/pdf | |
| dc.language.iso | en_US | |
| dc.publisher | Texas A&M University | |
| dc.rights | This thesis was part of a retrospective digitization project authorized by the Texas A&M University Libraries in 2008. Copyright remains vested with the author(s). It is the user's responsibility to secure permission from the copyright holder(s) for re-use of the work beyond the provision of Fair Use. | en |
| dc.subject | chemical engineering. | en |
| dc.subject | Major chemical engineering. | en |
| dc.title | Synthesis and characterization of zirconia aerogels | en |
| dc.type | Thesis | en |
| thesis.degree.discipline | chemical engineering | en |
| thesis.degree.name | M.S. | en |
| thesis.degree.level | Masters | en |
| dc.type.genre | thesis | en |
| dc.type.material | text | en |
| dc.format.digitalOrigin | reformatted digital | en |
Files in this item
This item appears in the following Collection(s)
-
Digitized Theses and Dissertations (1922–2004)
Texas A&M University Theses and Dissertations (1922–2004)
Request Open Access
This item and its contents are restricted. If this is your thesis or dissertation, you can make it open-access. This will allow all visitors to view the contents of the thesis.