Limestone conversion to cement clinker precursor in a zero-gap electrolyzer
Bibliographic record
Abstract
The carbon intensity of industrial cement production could be reduced if the high-temperature kilns used to decompose limestone (CaCO3(s)) were replaced. One possible solution is to use electrochemical reactors to convert CaCO3(s) into Ca(OH)2(s). The challenge is that the continuous-flow electrochemical reactors reported to date all require voltages that are too high (>4 V at 100 mA cm–2) to be put into practice. A key reason for these high voltages is that the reactors contain a chemical chamber, inserted between the anode and cathode chambers, that leads to a high Ohmic resistance. In this study, we present an electrolyzer that decomposes CaCO3(s) into reactive Ca2+ ions using only two chambers. This cell design, with an anode and cathode chamber separated by a membrane instead of a chemical chamber, follows a “zero-gap” design akin to hydrogen-producing electrolyzers and fuel cells. This cement electrolyzer is capable of operating at a full cell voltage (Ecell) of merely 0.38 V at 100 mA cm–2, and with 100% faradaic efficiency (FE). This strikingly low Ecell is 1.4 V lower than any other reported Ecell. We achieved this goal by not only eliminating the chemical chamber, but by also engaging the reversible redox activity of (hydro)anthraquinones to mediate oxidation and reduction within a narrow electrochemical window. This streamlined reactor is capable of operating at a record low voltages of 0.38 V at 100 mA cm–2, and 4.23 V at 1 A cm–2.
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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 | 0.001 |
| 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".