- Title
- Towards the use of solid oxide fuel cells for the chemical conversion and production of energy from biodiesel waste streams
- Creator
- Drewery, Matthew James
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2018
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Pressure to address the adverse environmental impact and issues of sustainability associated with the use of petroleum has resulted in the commercial development of biodiesel as a diesel replacement. The transesterification of fatty acids, which is used industrially in the production of biodiesel, also produces approximately 10 wt% glycerol as a major bi-product, rendering industrial synthesis of glycerol obsolete and causing its market value to drop significantly. The need to process the waste glycerol and value add to reduce the overall costs associated with biodiesel production has dramatically increased research into the use of glycerol as a platform chemical. There is also the opportunity to utilise solid oxide fuel cells to process this waste to produce energy through highly efficient electrochemical reactions. This research examines the potential for using glycerol as a fuel, either through direct oxidation or pre-reforming, in a solid oxide fuel cell. In this instance, a cell consisting of a nickel-based anode, 150 μm scandia-doped zirconia electrolyte and LSM cathode sourced from Fuel Cell Materials was used to examine potential feed streams, with an indigenous dynamic load cell used to evaluate performance. Glycerol has been identified as a potential solid oxide fuel cell feed owing to the presence of hydroxyl functional groups which are hypothesised to inhibit coke formation. Glycerol itself was shown to be a viable fuel feed for direct oxidation in solid oxide fuel cells, with reasonable power densities and minimal deactivation identified. Potential pre-reforming products were also examined as a feed, including synthesis gas, acrolein and allyl alcohol, with the later species used in conjunction with a H₂O/D₂O isotope study and C₃ mono-ol/diol study to investigate the interactions of OH species. It was found that hydroxyl species play an important role in anode surface chemistry, facilitating a transfer reaction from the anode to electrolyte for electrochemical oxidation, which through the use of isotopes was highlighted as a potential rate limiting process. It was also shown that oxygenated hydrocarbons are less likely to deactivate the anode via coke formation, with increasing the number of hydroxyl inhibiting carbonisation. The importance of hydroxyl interactions was seen in comparisons to similar molecules acrolein and allyl alcohol, common derivatives of glycerol, where it was found the hydroxyl containing allyl alcohol was directly oxidised on the anode surface while the carbonyl of the acrolein resulted in rapid carbon formation and anode deactivation. The highly oxygenated nature of glycerol also allows it to be utilised as a solid oxide fuel cell feed, where it was found that when fed into the anode chamber the fuel would oxidise (as opposed to internal reforming) without significant deactivation for over 90 hours operation. Industrial production of glycerol results in a number of potential impurities, in particular salts formed from the homogeneously catalysed transesterification reaction. It was identified that selection of these catalysts based on the salts produced (or modifications to heterogenous catalysis) needs to be considered, with the presence of sodium chloride resulting in the formation of nickel chloride on the anode surface causing anode deactivation.
- Subject
- solid oxide fuel cells; glycerol; hydroxyl; alcohol; biodiesel; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1393781
- Identifier
- uon:33609
- Rights
- Copyright 2018 Matthew James Drewery
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 6 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 1 MB | Adobe Acrobat PDF | View Details Download |