Woodfine, Sian Elizabeth (2020) Synthesis and characterisation of high silica zeolites for methane reforming. Doctoral thesis, Keele University.

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Abstract

In this study, the ability of the MTBA cation to effectively direct the formation of the nanosized MFI framework was present for the first time. Two nanosized materials from different SDAs were synthesised and investigated with a variety of different analytical techniques to ascertain the mechanism of formation. X-ray diffraction and dynamic light scattering studies showed varying results between the TPA and MTBA SDAs used, with the TPA templated material suggesting rapid crystallisation and the MTBA template material suggesting an aggregation mechanism. 13C and 29Si SSNMR studies of both materials suggest a spontaneous crystallisation mechanism is taking place. Conclusive evidence of a mechanism of formation was not observed, however it was concluded that the most likely mechanism was that of spontaneous rapid crystallisation. Further work into the mechanism of crystallisation needs to be conducted with a focus on size control and the effect of the SDA used.
The effect of crystallite size and framework topology on the catalysis of methane reforming was also studied using incorporated nickel as the active species. The catalytic activities for a nano sized and a micron sized nickel containing MFI zeolite were tested. The nano sized material was found to have a higher activity for the partial oxidation of methane, whereas the micron sized material was found to have a higher activity for the biogas reforming of methane. The catalytic activity for nickel containing MEL and MTW type materials was also tested. The MTW material showed a much higher activity for all methane reforming when compared to the MEL material. For the partial oxidation of methane, the MTW nickel containing material showed the highest activity, and for biogas reforming the micron sized MFI material showed the highest activity. It was concluded that the zeolite framework plays an important role in the catalysis of methane reforming and is not simply acting as a support for the active nickel species as the non- ‘doped’ materials show no catalytic activity. The effect of crystallite size is not shown to be equal for all reforming reactions. Further work into the location and activity of the nickel species with the framework needs to be conducted along with additional investigations into the wide variety of framework topologies available.

Item Type: Thesis (Doctoral)
Subjects: Q Science > QD Chemistry
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Lisa Bailey
Date Deposited: 15 May 2020 15:45
Last Modified: 15 May 2020 15:45
URI: https://eprints.keele.ac.uk/id/eprint/7994

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