Abstract
The research described in this thesis focuses on the electrochemical formation of green ammonia for fertilizer application. Since N2 reduction suffers from the extremely low activity and reliability, NOx are proposed as an alternative feed. Since NOx electroreduction in aqueous electrolytes suffers from mass transport limitations, a new type of electrode geometry was developed and tested for reduction of NO3- from liquid-, and NO from gas-phase to ammonia which can be applied as green fertilizer. Additionally, the possibility of electrochemical urea formation was investigated.
In Chapter 2 the preparation of Ti-based hollow fibers via dry-wet spinning has been investigated. Carefully designed, two-step thermal decomposition of the polymer involved in the spinning process, leads to the formation of entirely metallic titanium hollow fiber. Detailed characterization of prepared fibers reveals their porous structure and low resistivity making them suitable for electrochemical applications.
The activity of previously synthesized Ti hollow fibers has been tested for electroreduction of nitrate to ammonia in Chapter 3. Efficient mixing of the electrolyte was observed by inert gas bubbles coming from the inside of the porous electrode wall which results in significantly improved mass transport in the system. The target application is a partial transformation of nitrate to ammonium which results in ammonium nitrate formation.
In Chapter 4, Ti hollow fibers were modified with a Cu layer in order to enhance the ammonia formation from NOx. Nitric oxide with low solubility in aqueous solutions was chosen as a feed for ammonia synthesis. The reactant was supplied from the inside of the porous wall of the hollow fiber electrode which results in the creation of a three-phase boundary with an effective supply of NO greatly enhancing its conversion to green ammonia.
The possibility of urea formation in the simultaneous electroreduction of CO2 and NO3- on polycrystalline, rough Cu surfaces was studied in Chapter 5. Surface-Enhanced Raman Spectroscopy and Electrochemical Mass Spectrometry were used in order to determine adsorbed species that could potentially lead to C-N bond formation. Insight into this complex system provides information about carbon-nitrogen coupling reactions, and the impact on possible routes for urea electrosynthesis is discussed.
In Chapter 2 the preparation of Ti-based hollow fibers via dry-wet spinning has been investigated. Carefully designed, two-step thermal decomposition of the polymer involved in the spinning process, leads to the formation of entirely metallic titanium hollow fiber. Detailed characterization of prepared fibers reveals their porous structure and low resistivity making them suitable for electrochemical applications.
The activity of previously synthesized Ti hollow fibers has been tested for electroreduction of nitrate to ammonia in Chapter 3. Efficient mixing of the electrolyte was observed by inert gas bubbles coming from the inside of the porous electrode wall which results in significantly improved mass transport in the system. The target application is a partial transformation of nitrate to ammonium which results in ammonium nitrate formation.
In Chapter 4, Ti hollow fibers were modified with a Cu layer in order to enhance the ammonia formation from NOx. Nitric oxide with low solubility in aqueous solutions was chosen as a feed for ammonia synthesis. The reactant was supplied from the inside of the porous wall of the hollow fiber electrode which results in the creation of a three-phase boundary with an effective supply of NO greatly enhancing its conversion to green ammonia.
The possibility of urea formation in the simultaneous electroreduction of CO2 and NO3- on polycrystalline, rough Cu surfaces was studied in Chapter 5. Surface-Enhanced Raman Spectroscopy and Electrochemical Mass Spectrometry were used in order to determine adsorbed species that could potentially lead to C-N bond formation. Insight into this complex system provides information about carbon-nitrogen coupling reactions, and the impact on possible routes for urea electrosynthesis is discussed.
| Original language | English |
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| Qualification | Doctor of Philosophy |
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| Supervisors/Advisors |
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| Award date | 13 May 2022 |
| Place of Publication | Enschede |
| Publisher | |
| Print ISBNs | 978-90-365-5377-3 |
| DOIs | |
| Publication status | Published - 13 May 2022 |