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Title: TPD and steady-state kinetic studies of catalysts
Author: Jiang, W.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2002
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The first part is the use of a variety of temperature programmed desorption techniques, analytical studies and numerical simulation to see whether it is possible to identify differences in the nature and number of hydroxyl groups associated with Cabosil and sol-gel silicas. The motivations of this work are to examine the strength of this technique to provide quantitative information about the heterogeneous surface and to explore the effects of different kinetic parameters on TPD spectra through both analytical and Monte Carlo methods. The second part of this thesis focuses on using a Monte Carlo Lattice Dynamic code simulating temperature-programmed desorption to obtain a molecular level understanding of the desorption of hydrocarbon and aromatic species from the zeolite silicalite. Excellent agreement between experimental and simulated results is obtained and the results have been interpreted in terms of the rate of site-desorption events of the adsorbed species inside silicalite framework. Finally the modelling and discussion provide further insight into the adsorption mechanism of n-heptane in silicalite. The final part of this work is to set up a microreactor system to study ethene hydrogenation reaction over eight different Pt/alumina catalysts, which differ in terms of the alumina support and metal profile, and to see to what extent differences in reactivity correlate with any physical and chemical characterisation data. Temperature programmed desorption has been used to characterise the catalysts (Pure alumina, IMI-Pt-17 and IMI-Pt-18). The reactor data are also compared with the results of a Monte Carlo simulation of the ethene hydrogenation reaction. A comparison of the TPD data of ethene and hydrogen on pure support and Pt/Al2O3 with a microreactor study suggests that the presence of the transition is associated with alumina support. Therefore a new reaction mechanism including hydrogen spillover on the support is proposed to explain the kinetic transition in ethene reaction orders for ethene hydrogenation over supported metal catalysts.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available