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Zeolite microstructured reactors

Wan, Yu Shan Susanna; (2003) Zeolite microstructured reactors. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Microreactors can provide better energy and material utilization leading to efficient chemical production. Due to the large surface area to volume ratio, the heat and mass transfer efficiency can be maximized. Reactions can also be performed under safe and automated conditions ensuring minimal environmental impact. Zeolites can be precisely tailored up to the sub-nanometer scale. They are of great interest in catalysis and separation, which serve as the best candidate material for incorporation in microchemical systems. Titanium silicalite-1 zeolite (TS-1) is known to be an efficient catalyst for selective oxidation of alcohols, epoxidation of alkenes and hydroxylation of aromatics. The techniques to incorporate zeolite in microchemical devices were pioneered. Zeolites (Silicalite-1, ZSM-5 and TS-1) can be employed as catalysts, membrane or structural materials. Traditional semiconductor fabrication technology was employed in micromachining the device architecture. Three novel strategies for manufacturing zeolite microchemical devices have been successfully demonstrated: localized zeolite growth, etching of zeolite-silicon composite film and free-standing zeolite membrane in microseparator. The first prototype of zeolite-based single channel microreactor was successfully experimented for 1-pentene epoxidation over TS-1 catalyst. A simple computation model was developed to study the influence of reactor geometry, catalyst properties and reaction conditions to improve the microreactor performance. TS-1 coatings with different titanium-contents and crystal grain sizes were studied. Short-term deactivation of TS-1 was observed due to the formation of organic compounds and presence of water by product. Long-term deactivation by titanium leaching was irreversible. In order to selectively remove water, which is one of the byproducts, a multi-channel membrane microreactor was designed and fabricated. The reaction studied was TS-1 catalysed selective oxidation of aniline while the membrane material was hydrophilic ZSM-5. Deactivation of the catalyst was reduced with improved product selectivity. In this thesis, different strategies for incorporating zeolite in microreactors were studied. The microreactors were successfully tested and their various applications have been demonstrated. These results have provided an insight to improve the design of zeolite microstructured reactors.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Zeolite microstructured reactors
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Applied sciences; Zeolites
URI: https://discovery.ucl.ac.uk/id/eprint/10098938
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