Electrochemically induced CO2 capture enabled by aqueous quinone flow chemistry
Bibliographic record
Abstract
Climate change caused by the accumulation of anthropogenic CO2 emissions motivates the development and deployment of cost-effective, scalable, and energetically efficient techniques to capture CO2 from point or diffuse sources. Electrochemically-driven CO2 capture processes utilizing redox-active organics in aqueous flow chemistry show promise for nonflammability, continuous-flow engineering, and the possibility of being driven at high current density by inexpensive, clean electricity. We show that the deprotonated hydroquinone-CO2 adducts, whose insolubility limits the utility of the quinone-hydroquinone redox couple, become soluble when alkylammonium cations are introduced. Consequently, we introduce alkylammonium groups to anthraquinone via covalent bonds, making the resulting bis[3-(trimethylammonio)propyl]-anthraquinones (BTMAPAQs) soluble. We report the first aqueous quinone flow chemistry-enabled electrochemical CO2 capture process, which occurs at ambient temperature and pressure, and show that it proceeds via both a pH-swing and a nucleophilicity-swing mechanism. 1,5-BTMAPAQ reaches the theoretical capture capacity of two CO2 molecules per quinone from 1-bar CO2-N2 mixtures for which the CO2 partial pressure is as low as 0.05 bar, or the applied current density is as high as 100 mA/cm2, or the organic concentration is as high as 0.4 M. The energetic cost ranges from 48 to 140 kJ/molCO2. In a crude simulated flue gas composed of 3% O2, 10% CO2, and 87% N2, 1,5-BTMAPAQ electrolyte reversibly captured and released 50% of the theoretical capacity during an exposure of over 4 hr. It outperforms its isomeric counterparts 1,4-, and 1,8-BTMAPAQ in capture capacity and O2 tolerance, demonstrating a substituent position effect on the reactivity of isomers with CO2 and O2. The results provide fundamental insight into electrochemical CO2 capture with aqueous quinone flow chemistry and suggest that oxygen tolerance of reduced quinones may be significantly advanced through molecular engineering.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".