Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2017
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| Online Access: | http://hdl.handle.net/1721.1/111749 |
| _version_ | 1826193099681955840 |
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| author | Khurram, Aliza |
| author2 | Betar M. Gallant. |
| author_facet | Betar M. Gallant. Khurram, Aliza |
| author_sort | Khurram, Aliza |
| collection | MIT |
| description | Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. |
| first_indexed | 2024-09-23T09:34:03Z |
| format | Thesis |
| id | mit-1721.1/111749 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T09:34:03Z |
| publishDate | 2017 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1117492021-10-09T04:57:17Z Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/ Khurram, Aliza Betar M. Gallant. Massachusetts Institute of Technology. Department of Mechanical Engineering. Massachusetts Institute of Technology. Department of Mechanical Engineering. Massachusetts Institute of Technology. Department of Mechanical Engineering Mechanical Engineering. Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (pages 66-70). The development of effective CO₂ capture and conversion methods is not only crucial for mitigating rising global atmospheric CO₂ concentrations but also for exploiting atmospheric carbon dioxide as a potential source of C1 feedstock for the industrial synthesis of fuels and chemicals. Herein, we report a combined chemical-electrochemical device for postcombustion capture and subsequent conversion of CO₂ into a benign, solid alkali metalcontaining phase (lithium carbonate, Li2CO₃). The capture is accomplished in a non-aqueous battery electrolyte containing a molecular CO₂ sorbent, and the conversion is initiated at an electrode surface, which advantageously combines two conventionally separate approaches to CO₂ mitigation. In particular, the proposed system utilizes an amine, namely 2- ethoxyethylamine (EEA) in an organic electrolyte (dimethyl sulfoxide) to activate the CO₂ molecule via chemisorption prior to electrochemical reduction at a simple carbon electrode in a Li-CO₂ battery configuration. We show that by decoupling the first electron transfer step from the structural rearrangement of the CO₂ molecule, we are able to electrochemical CO₂ reduction kinetically accessible. In order to demonstrate that bending the CO₂ molecule prior to delivering it to an electrode surface for reduction facilitates the rate limiting step in classical electrochemical reduction, we investigated the energetics of chemically complexed CO₂ reduction via galvanostatic discharge testing of Li-CO₂ cells. Our results indicate that the electrochemical reduction of complexed amines containing the bent CO₂ molecules proceed at significantly higher discharge potentials (~3 V vs. Li) compared to the gaseous, dissolved (uncomplexed) CO₂ , the gaseous, physically absorbed CO₂, and yield high discharge capacities (> 1000 mAh/gc), thus functioning effectively as a primary battery. To elucidate the reaction mechanism, we employed a series of solid-phase product characterization techniques. Our results revealed that the proposed system converts bound CO₂ to primarily solid-phase amorphous lithium carbonate, which has the potential to eliminate the energetic and logistical costs associated with long-term underground storage of compressed CO₂ in conventional carbon capture technologies. Additionally, through liquid phase analyses, we present evidence for selective cleavage of the bond -N-C- (i.e. the bond formed between the amine and CO₂ when amine binds the CO₂ molecule) upon electrochemical reduction of loaded amine species. Furthermore, an analysis of the system's performance under varying conditions such as applied current density and amine concentration is presented. The likely full cell reaction, the possibility of formation of any secondary products and final state of the amine is also discussed. by Aliza Khurram. S.M. 2017-10-04T15:06:44Z 2017-10-04T15:06:44Z 2017 2017 Thesis http://hdl.handle.net/1721.1/111749 1004512908 eng MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission. http://dspace.mit.edu/handle/1721.1/7582 ix, 70 pages application/pdf Massachusetts Institute of Technology |
| spellingShingle | Mechanical Engineering. Khurram, Aliza Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/ |
| title | Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/ |
| title_full | Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/ |
| title_fullStr | Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/ |
| title_full_unstemmed | Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/ |
| title_short | Amine-mediated electrochemical reduction of CO₂ in a nonaqueous, Li-CO₂ battery/ |
| title_sort | amine mediated electrochemical reduction of co₂ in a nonaqueous li co₂ battery |
| topic | Mechanical Engineering. |
| url | http://hdl.handle.net/1721.1/111749 |
| work_keys_str_mv | AT khurramaliza aminemediatedelectrochemicalreductionofco2inanonaqueouslico2battery |