George, Ashley Roger;
(1994)
Computational studies of microporous materials.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The use of computational modelling is becoming evermore prominent in the area of solid state chemistry and indeed with the continuing advances in computational power, it is possible to investigate the interesting and demanding areas associated with heterogeneous catalysis. In the first half of this thesis, it is shown how a range of contemporary computational techniques, (including Molecular Dynamics and ab-initio calculations), can be used to explain in detail the structural and mechanistic features associated with a complex catalytic process, the cyclotrimerisation of acetylene to benzene in the presence of Nickel substituted zeolite-Y. In such a process, the ligand itself plays a vital role in extracting the cation into a more accessible site and then, via electrostatic and short-range forces, the acetylene molecules react in a manner that is significantly different from the classical Diels-Alder type of concerted ring formation. In the latter half of this thesis, we study several problems in solid state chemistry prior to their experimental investigation. In particular, solid solutions of GeO₂/SiO₂ polymorphs, with similar structures to several zeolites are predicted to be stable. In addition, the details of the phase transition of GeO₂ α-quartz to the more stable rutile structure have been modelled successfully. Finally, computational modelling has been applied to the investigation of a new member of the Clathrasil family, Octadecasil. This structure was found to be stable without the presence of extraframework ions. This line of investigation was continued with the study of the energetics of exchange with various ions, which allows us to evaluate the potential of this structure for use as an ion-exchange material.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Computational studies of microporous materials |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Thesis digitised by ProQuest. |
| Keywords: | Pure sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10106215 |
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